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- Swimming Anatomy
See how to achieve stronger starts, more explosive turns, and faster times! Swimming Anatomy will show you how to improve your performance by increasing muscle strength and optimizing the efficiency of every stroke.
Swimming Anatomy includes 74 of the most effective swimming exercises, each with step-by-step descriptions and full-color anatomical illustrations highlighting the primary muscles in action.
Swimming Anatomy goes beyond exercises by placing you on the starting block, in the water, and into the throes of competition. Illustrations of the active muscles for starts, turns, and the four competitive strokes (freestyle, breaststroke, butterfly, and backstroke) show you how each exercise is fundamentally linked to swimming performance.
You'll also learn how exercises can be modified to target specific areas, improve your form in the water, and minimize common swimming injuries. Best of all, you'll learn how to put it all together to develop a training program based on your individual needs and goals.
Whether you are training for a 50-meter freestyle race or the open-water stage of a triathlon, Swimming Anatomy will ensure you enter the water prepared to achieve every performance goal.
Exercise Finder
Foreword
Chapter 1. The Swimmer in Motion
Chapter 2. Arms
Chapter 3. Shoulders
Chapter 4. Chest
Chapter 5. Abdomen
Chapter 6. Back
Chapter 7. Legs
Chapter 8. Whole-Body Training
About the Author
USA Swimming, the largest swimming organization in the world, specifically recommended Ian McLeod as the author of Swimming Anatomy. McLeod has extensive experience working with world-class athletes, particularly swimmers. A certified athletic trainer and certified massage therapist, he was a member of the U.S. team's medical staff at the 2008 Summer Olympic Games in Beijing. He has also worked extensively as an athletic trainer with the sports programs at the University of Virginia and Arizona State University.
McLeod remains deeply involved with USA Swimming's High Performance Network, a group of volunteer health professionals who support U.S. swimmers at national and international meets. He has been given the organization's highest honor, the Gold Standard Award. McLeod also served as massage therapist to the Egyptian national swim team during the 2004 Olympic Games in Athens. He has provided athletic training and sport massage to swimming stars such as Ed Moses, Kaitlin Sandeno, Natalie Coughlin, and Jason Lezak.
McLeod lives in Tempe, Arizona, with his wife and two children.
"With full-color exercises and drills, Swimming Anatomy takes an inside look at the muscles you need to strengthen in order to swim your best. This is a must-have guide for every swimmer."
Jason Lezak
2008 Olympic Bronze Medalist in 100-meter freestyle
2008 Olympic Gold Medalist (World Record) in 4 X 100 freestyle relay
2008 Olympic Gold Medalist (World Record) in 4 X 100 medley relay
"Ian McLeod, one of the most intelligent minds in swimming, demonstrates how to care for swimmers both in and out of the water, making Swimming Anatomy an essential resource for anyone involved in competitive swimming."Keenan Robinson
Athletic Trainer for University of Michigan Swimming and Diving"Buy Swimming Anatomy and treat it as the authoritative liftoff into the world of aquatic strength and conditioning."
Swimming World magazine
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
Back squat to improve swimming
Try these squats to strengthen legs for improved swimming performance.
Execution
1. Rest the barbell across your upper back and position your feet shoulder-width apart.
2. Initiating the movement with your hips, squat down until your thighs are parallel to the ground.
3. Return to the starting position by straightening your legs.
Muscles Involved
Primary: Rectus femoris, vastus medialis, vastus intermedius, vastus lateralis, gluteus maximus, gluteus medius
Secondary: Erector spinae, biceps femoris, semitendinosus, semimembranosus, adductor magnus, adductor longus, adductor brevis, pectineus, sartorius, gracilis, transversus abdominis, external oblique, internal oblique
Swimming Focus
Squats are a good all-around exercise because they recruit all major muscles groups of the lower extremity. Increasing the strength of the knee extensors transfers to improved force generation and endurance when kicking, regardless of stroke. Strengthening of the gluteal muscles, specifically the gluteus maximus, helps to improve the force that is generated with the extension of the hip during the breaststroke kick. Because of the similarities in the movements performed in squats and starts, particularly flat starts, squats should be a mainstay exercise for enhancing a swimmer's start.
Extra caution should be used because of the potential for injury to the low back or knees. To protect the low back, beginners should start with just the bar until they are fully comfortable with the exercise. Emphasizing tightening of the core musculature, as described in the introduction to chapter 5, will also help protect the low back. The most common causes for injury to the knee are shifting of the knees forward past the toes or allowing the knees to collapse inward when squatting down.
This is an excerpt from Swimming Anatomy.
Master the freestyle and the butterfly
Use these simple tips and images to improve your swimming strokes.
Freestyle
As the hand enters into the water, the wrist and elbow follow and the arm is extended to the starting position of the propulsive phase. Upward rotation of the shoulder blade allows the swimmer to reach an elongated position in the water. From this elongated position, the first part of the propulsive phase begins with the catch. The initial movements are first generated by the clavicular portion of the pectoralis major. The latissimus dorsi quickly joins in to assist the pectoralis major. These two muscles generate a majority of the force during the underwater pull, mostly during the second half of the pull. The wrist flexors act to hold the wrist in a position of slight flexion for the entire duration of the propulsive phase. At the elbow, the elbow flexors (biceps brachii and brachialis) begin to contract at the start of the catch phase, gradually taking the elbow from full extension into approximately 30 degrees of flexion. During the final portion of the propulsive phase the triceps brachii acts to extend the elbow, which brings the hand backward and upward toward the surface of the water, thus ending the propulsive phase. The total amount of extension taking place depends on your specific stroke mechanics and the point at which you initiate your recovery. The deltoid and rotator cuff (supraspinatus, infraspinatus, teres minor, and subscapularis) are the primary muscles active during the recovery phase, functioning to bring the arm and hand out of the water near the hips and return them to an overhead position for reentry into the water. The arm movements during freestyle are reciprocal in nature, meaning that while one arm is engaged in propulsion, the other is in the recovery process.
Several muscle groups function as stabilizers during both the propulsive phase and the recovery phase. One of the key groups is the shoulder blade stabilizers (pectoralis minor, rhomboid, levator scapula, middle and lower trapezius, and the serratus anterior), which as the name implies serve to anchor or stabilize the shoulder blade. Proper functioning of this muscle group is important because all the propulsive forces generated by the arm and hand rely on the scapula's having a firm base of support. Additionally, the shoulder blade stabilizers work with the deltoid and rotator cuff to reposition the arm during the recovery phase. The core stabilizers (transversus abdominis, rectus abdominis, internal oblique, external oblique, and erector spinae) are also integral to efficient stroke mechanics because they serve as a link between the movements of the upper and lower extremities. This link is central to coordination of the body roll that takes place during freestyle swimming.
Like the arm movements, the kicking movements can be categorized as a propulsive phase and a recovery phase; these are also referred to as the downbeat and the upbeat. The propulsive phase (downbeat) begins at the hips by activation of the iliopsoas and rectus femoris muscles. The rectus femoris also initiates extension of the knee, which follows shortly after hip flexion begins. The quadriceps (vastus lateralis, vastus intermedius, and vastus medialis) join the rectus femoris to help generate more forceful extension of the knee. Like the propulsive phase, the recovery phase starts at the hips with contraction of the gluteal muscles (primarily gluteus maximus and medius) and is quickly followed by contraction of the hamstrings (biceps femoris, semitendinosus, and semimembranosus). Both muscle groups function as hip extensors. Throughout the entire kicking motion the foot is maintained in a plantarflexed position secondary to activation of the gastrocnemius and soleus and pressure exerted by the water during the downbeat portion of the kick.
Butterfly
The primary difference between freestyle and butterfly is that the arms move in unison during butterfly whereas reciprocal movements take place with freestyle. Because butterfly and freestyle have the same underwater pull pattern, the muscle recruitment patterns are almost identical. As with freestyle, the swimmer's arms in butterfly are in an elongated position when they initiate the propulsive underwater portion of the stroke. Muscles active during the entire propulsive phase are the pectoralis major and latissimus dorsi, which function as the primary movers, and the wrist flexors, which act to maintain the wrist in a neutral to slightly flexed position. The biceps brachii and brachialis are active as the elbow moves from being fully extended at the initiation of the catch to approximately 40 degrees of flexion during the midpart of the pull. Unlike in freestyle, a forceful extension of the elbow is emphasized during the final portion of the pull, resulting in greater demands being placed on the triceps brachii. As in the freestyle stroke, both the rotator cuff and deltoid are responsible for moving the arm during the recovery phase, but the mechanics are somewhat different. Butterfly lacks the body roll that aids the recovery process during freestyle; instead, an undulating movement of the torso occurs, which brings the entire upper torso out of the water to aid in the recovery process.
Again, the shoulder blade stabilizing muscles are extremely important, because they function to provide a firm anchor point for the propulsive forces generated by the arms and help reposition the arms during the recovery phase of the stroke. Although butterfly lacks the body roll present in freestyle, the core stabilizers are still important in linking the movements of the upper and lower extremities and have an important role in creating the undulating motion that allows the swimmer to get the upper torso and arms out of the water during the recovery process. The undulating movement is initiated with contraction of the paraspinal muscles that run in multiple groups from the lower portion of the back to the base of the skull. This contraction results in an arching of the back, at which time the arms are moving through the recovery process. Contraction of the abdominal muscles quickly follows, which prepares the upper body to follow the entry of the hands into the water to initiate the propulsive phase of the stroke.
As with the arms, the muscles used in generating the kicking movements during the butterfly kick are identical to those used during the freestyle kick; the only difference in kick mechanics is that the legs move in unison. The propulsive downbeat begins with contraction of the iliopsoas and rectus femoris, acting as hip flexors. The rectus femoris also initiates knee extension, and associated firing of the quadriceps muscle group further aids in extension of the knee. The gluteal muscle group drives the recovery phase of the kick. Concomitant contraction of the hamstring muscles also works to extend the hip. The foot is maintained in a plantarflexed position through a combination of the resistance from the water and activation of the gastrocnemius and soleus, acting as plantarflexors. The dolphin kick that is used at the start of the race and off each turn wall recruits a larger group of muscles than the smaller, more isolated kick tied into the arm movements. Besides the movements generated at the hips and knee, the dolphin kick ties in the undulating movements of the torso through activation of the core stabilizers and the paraspinal musculature.
This is an excerpt from Swimming Anatomy.
A strong core is essential for powerful swimming
Swimmers need strong core muscles to move through the water efficiently.
To move your body efficiently through the water, a coordinated movement of the arms and legs must occur. The key to this coordinated movement is a strong core, of which the muscles of the abdominal wall are a primary component. Besides helping to link the movement of the upper and lower body, the abdominal muscles assist with the body-rolling movements that take place during freestyle and backstroke and are responsible for the undulating movements of the torso that take place during butterfly, breaststroke, and underwater dolphin kicking.
The abdominal wall is composed of four paired muscles that extend from the rib cage to the pelvis. The muscles can be divided into two groups—a single anterior group and two lateral groups that mirror each other. The anterior group contains only one paired muscle, the rectus abdominis, which is divided into a right and left half by the midline of the body. The two lateral groups each contain a side of the remaining three paired muscles—the external oblique, internal oblique, and transversus abdominis (figure 5.1). In human motion and athletics, the abdominal muscles serve two primary functions: (1) movement, specifically forward trunk flexion (curling the trunk forward), lateral trunk flexion (bending to the side), and trunk rotation; and (2) stabilization of the low back and trunk. The motions mentioned earlier result from the coordinated activation of multiple muscle groups or the activation of a single muscle group.
The rectus abdominis, popularly known as the six pack, attaches superiorly to the sternum and the surrounding cartilage of ribs 5 through 7. The fibers then run vertically to attach to the middle of the pelvis at the pubic symphysis and pubic crest. The six-pack appearance results because the muscle is divided by and encased in a sheath of tissue called a fascia. The visible line running along the midline of the body dividing the muscle in two halves is known as the linea alba. Contraction of the upper fibers of the rectus abdominis curls the upper trunk downward, whereas contraction of the lower fibers pulls the pelvis upward toward the chest. Combined contraction of both the upper and lower fibers rolls the trunk into a ball.
The muscles of the two lateral groups are arranged into three layers. The external oblique forms the most superficial layer. From its attachment on the external surface of ribs 5 through 12, the fibers run obliquely (diagonally) to attach at the midline of the body along the linea alba and pelvis. If you were to think of your fingers as the fibers of this muscle, the fibers would run in the same direction as your fingers do when you put your hand into the front pocket of a pair of pants. Unilateral (single-sided) contraction of the muscle results in trunk rotation to the opposite side, meaning that contraction of the right external oblique rotates the trunk to the left. Bilateral contraction results in trunk flexion.
The next layer is formed by the internal oblique. The orientation of its fibers is perpendicular to those of the external oblique. This muscle originates from the upper part of the pelvis and from a structure known as the thoracolumbar fascia, which is a broad band of dense connective tissue that attaches to the spine in the upper- and lower-back region. From its posterior attachment, the internal oblique wraps around to the front of the abdomen, inserting at the linea alba and pubis. Unilateral contraction rotates the trunk to the same side, and bilateral contraction leads to trunk flexion. The deepest of the three layers is formed by the transversus abdominis, so named because the muscle fibers run transversely (horizontally) across the abdomen. The transversus abdominis arises from the internal surface of the cartilage of ribs 5 through 12, the upper part of pelvis, and the thoracolumbar fascia. The muscle joins with the internal oblique to attach along the midline of the body at the linea alba and pubis. Contraction of the transversus abdominis does not result in significant trunk motion, but it does join the other muscles of the lateral group to function as a core stabilizer. An analogy that often helps people grasp the core-stabilizing function of the muscles of the lateral group is to think of them as a corset that, when tightened, holds the core in a stabilized position.
This is an excerpt from Swimming Anatomy.
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