Running Form
How to Run Faster and Prevent Injury
232 Pages
For many runners, running technique is an afterthought—one they don’t think about until an injury or plateau keeps them from achieving their goals. Running Form underscores the importance of proper form and shows you how to elevate your performance to the greatest possible extent with the smallest risk of injury.
Owen Anderson, PhD, is a coach to elite runners from around the globe. In Running Form, he describes the common problem of runners moving on “square wheels” by braking with each step, adopting inefficient stances, or risking injury with excessive ground impact. He pinpoints the components of good form—foot-strike, shin and shank angle, stance time, cadence, body lean, and posture—to help you understand where you can make small changes that offer significant improvements.
Then, using a basic video camera or smartphone, you can analyze your own form and apply specific drills and exercises to correct any deficiencies. Numerous photos incorporate lines and arrows to help you clearly identify the appropriate angles and movements of sound technique. No expensive software or biomechanics degree is required to learn how to run faster and with more efficiency and to significantly reduce your risk of injury.
Get rid of those running patterns that hurt performance and destroy running economy. Running Form gives you the knowledge to perfect your running form so you can train consistently and improve with each stride.
Introduction. The Importance of Form
Part I. Why Form Matters
Chapter 1. Traditional Views on Form
Chapter 2. Comparing Ordinary and Elite Runners
Chapter 3. The Elements of Form
Chapter 4. How Form Can Enhance Performance and Prevent Injury
Part II. Assessing and Improving Form
Chapter 5. Assessing Form
Chapter 6. Improving Foot-Strike Patterns
Chapter 7. Upgrading Shank Angle
Chapter 8. Shortening Stance Time and Increasing Cadence
Chapter 9. Improving Body Lean
Chapter 10. Promoting Positive Posture
Chapter 11. Putting It All Together
Part III. Form Factors for Running Success
Chapter 12. Running Shoes
Chapter 13. Performance, Gender, and Age-Based Differences in Form
Chapter 14. Running-Specific Strength Training
Chapter 15. Integrating Form Work Into Your Seasonal Training
References
Index
About the Author
Owen Anderson, PhD, is the coach and manager of some of the best runners in the world, including Cynthia Limo (silver medalist in the 2016 IAAF World Half Marathon Championship and first-ranked road racer in the world according to ARRS in 2016), Mary Wacera (world silver and bronze medalist in the 2014 and 2016 IAAF World Half Marathons), Monicah Ngige (two-time winner of the Cooper River Bridge Run 10K and champion of the 2017 Monterey Bay Half Marathon), Mary Wangui (victor at the 2017 Tulsa Run 15K), Iveen Chepkemoi (first in the 2017 AK Sotik Cross Country meeting in Kenya), and Gladys Kipsoi (winner of the 2017 Pittsburgh Half Marathon).
Owen is the author of five books on running: Lactate Lift-Off,Great Workouts for Popular Races, Aurora, Running Science, and Running Form. He has written hundreds of articles on running for publications such as National Geographic Adventure, Runner’s World, Shape, Men’s Health, Peak Performance, Sports Injury Bulletin, and Running Research News.
Owen has been a featured speaker at symposiums around the world, including seminars at City University, London; Osaka University; and the University of Tokyo. Owen, who speaks Swahili fluently, has traveled to Kenya on 25 different occasions to manage running camps, recruit elite athletes, and study the training habits and nutritional practices of elite Kenyan runners. During the summer, he hosts running camps throughout the United States.
In his free time, Owen enjoys helping kids. He assisted in rescuing Kenyan children from the Tana Delta region during the savage conflicts of 2013 and has helped these young people resume their academic pursuits.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.
Perfect your one-leg squats
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
This exercise enhances vertical propulsive force during ground contact, promotes stability during stance, and upgrades running economy and fatigue resistance.
Repetition
Perform two sets of 12 reps on each leg, with a short break of about 10 seconds in between.
Action
Maintain good posture as you squat. Don't lean forward with your upper body, rather let your torso descend during the squat until the hip of the squatting (support) leg is on a level with the knee. Then, straighten the leg and return to starting position. Balance the toes of the rear foot on a step or bench behind you, being careful not to bear any weight on the rear foot. During each squat, the knee of the non-support, rear leg should descend downward toward a line perpendicular to the support foot at the heel. Begin the one-leg squats with no added resistance. As strength and stability increase, gradually add resistance by holding steadily heavier dumbbells or by positioning a weighty bar on the shoulders (figure 14.2a and b).
Learn more about Running Form.
Running shoes and form
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door.
When you wake up in the morning and slip into your running shoes in preparation for a run, you have unknowingly changed your running form in a significant way without even taking your first step out the door. That's because research reveals that running shoes have a profound effect on form. Compared with sauntering out the door barefooted or in minimal running shoes, traditional running shoes with elevated, cushioned heels steer you toward the following gait patterns.
Pattern A: Impact Transient
In traditional running shoes, a runner maximizes the “impact transient” (an abrupt collision force acting on the leg during the first 50 milliseconds of stance after the foot hits the ground), compared with barefoot running or running in minimal shoes. The magnitude of the impact transient is three times greater in traditional running shoes, compared with unshod running. In other words, your running shoes, thought to protect you from the impact forces of running, can actually increase the impact forces (1) (figure 12.1).
Figure 12.1 Running in conventional shoes is associated with a dramatic impact transient—a powerfully increasing impact force moving up the leg during the first 50 milliseconds of stance.
Pattern B: Heel Strike
In traditional running shoes, the ankle is less plantar-flexed each time the foot hits the ground. This means that a runner is much more likely to make initial contact with the ground with the rear portion of the foot, instead of the front area (in other words, the runner would be running with a rearfoot or heel-strike pattern) (2) (figure 12.2).
a | b |
Figure 12.2 The modern running shoe tends to steer runners away from (a) a more natural unshod landing pattern on the ground, and toward (b) a landing pattern that features a dorsiflexed ankle and a ground strike on the rear portion of the foot.
Pattern C: Knee Angle
In traditional running shoes, the knee is almost always less flexed at ground contact, meaning that the runner is hitting the ground with a significantly straighter leg, compared with running barefooted or in minimal shoes (3). The “knee angle” (the angle made by the posterior portions of the thigh and calf) for almost all runners wearing traditional, heel-elevated shoes is consistently in the range of 166 to 180 degrees at ground contact (4) (figure 12.3a).
By contrast, knee angles for barefooted runners, athletes wearing minimal running shoes with non-elevated heels, and runners who have carried out the running-form drills outlined in this book, fall within the range of 148 to 158 degrees for middle-distance and distance runners and 158 to 166 degrees for sprinters at ground contact (5) (figure 12.3b).
a | b |
Figure 12.3 (a) In traditional shoes, the knee angle is larger at impact with the ground, meaning that the leg is straighter. (b) For the barefoot runner or the runner in minimal shoes, the knee angle is less at the moment of impact, meaning that the knee is less straight (the knee is more flexed).
Landing on the heel with the ankle dorsi-flexed and a straight leg is responsible for the heightened impact transient in thick-heeled, traditional running shoes. If this is difficult to understand, think for a moment of the leg as being an iron pole that strikes the ground at high speed. Contrast that with an elastic appendage that can bend and store energy at its base (the foot), near its bottom (the ankle) and also at its middle (the knee). During the first 50 milliseconds after impact with the ground, which of these two structures would experience the greatest impact force in its top region (the end of the structure farthest from the ground)? It seems obvious that the knee, hip, and thus the spine would take greater, destructive poundings in traditional shoes, compared with running barefooted or the use of minimal shoes.
Impact Forces in Heel-Strikers
When a runner lands on the ground with his heel and a straight (or nearly straight) leg, the force of impact is transmitted extremely rapidly, straight through the heel (which cannot store energy by flexing as the ankle does), straight through the unflexed knee and ramrod-straight leg, and then through the hip to the spine and thus all the way to the head. A pronounced heel-first landing sets off a chain reaction of shock transmission throughout the entire body. This chain of events begins with a sledgehammer-like impact on the posterior aspect of the calcaneus (heel bone) and progresses nearly instantaneously through the leg, hip, and upper body. Research reveals that the sledgehammer landings are not effectively moderated by the high, foamy heels of traditional shoes (in fact, the impact transient can be three times greater in such shoes).
When the heel strikes the ground during a rearfoot-strike, the impact shock force moves upward in the following way:
- From the initial hammer strike on the calcaneus, up through the talus via the subtalar joint (figure 12.4)
- From the talus into the tibia (shin bone) via the tibio-talar joint
- From the tibia directly into the femur (thigh bone) by means of the tibio-femoral joint
- From the femur into the pelvis (hip) via the acetabulo-femoral joint
- From the pelvis into the vertebral column (spine) via the sacroiliac joint
- From the spine into the cranium via the cranio-vertebral joint (figure 12.5)
The calcaneus is neither positioned nor structured to store and release energy by elastically flexing and recoiling after impact with the ground. As a result, the shock force of landing is transmitted straight up the body to the head in milliseconds. This brutal scenario occurs about 7,000 times during a simple run of 5 miles (or 8 kilometers); it is a key reason why at least 65 percent of runners (and 90 percent of marathon trainees) experience a running-related injury in any given year (remember that 95 percent of runners are heel-strikers) (6). The fast transmission of impact shock with rearfoot-striking is especially troubling when one considers the relatively poor functional strength of the legs in many runners.
Figure 12.4 With a heel strike, impact force is transmitted quickly through the calcaneus and talus into the tibia.
Figure 12.5 With heel-striking, the impact transient is magnified and impact forces travel quickly up the skeletal chain to the head.
Learn more about Running Form.
Understand key elements of form assessment
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury.
Six key elements of form assessment represent the biggest influencers of performance, running economy, and risk of injury. Therefore, these six should be measured carefully via video analysis:
- Determination of how far ahead of the body the leg moves during the swing phase of gait and thus calculation of maximum shank angle (MSA)
- Measurement of reversal of swing (ROS), or how far back the shank and foot move from MSA before hitting the ground
- Determination of the ROS-to-MSA ratio (ROS/MSA)
- Measurement of the shank angle at initial impact with the ground (SAT, or shank angle at touchdown)
- Determination of the foot angle at touchdown (FAT)
- Confirmation of posture
A smartphone with video capabilities or a video camera are necessary to carry out the video analysis. The brand of the device does not matter, but the video instrument must be capable of recording at a rate of no less than 240 fps (frames per second).
Bear in mind that it is critical to determine MSA, ROS, SAT, and FAT with great precision. If you cannot determine exactly when a runner's foot strikes the ground, for example, you will not be able to assess SAT and FAT accurately.
Take the case of a runner moving along with a cadence of 180 steps per minute (three steps per second). As she runs, the goal is to “see” the exact moment when each foot makes contact with the ground—the precise instant when the stance phase of gait begins and SAT and FAT can be measured. Imagine what might happen if the video device were taking images at only 30 frames per second: That would mean an image would be captured every 1000/30 = 33.33 milliseconds.
That may seem like plenty of footage. But when a video device captures only 30 frames per second, it will be impossible to tell if the first frame showing the foot touching the ground represents initial impact, or if it shows the foot after it has been on the ground for a number of milliseconds. In the intervening milliseconds after the true initial impact, the runner's body may have moved significantly ahead over the foot, and thus the shank angle might have changed significantly. In other words, the measured SAT would be wrong.
Now, imagine this same scenario with a video device recording at 240 Hz. Instead of 33 milliseconds between images, there are now 1000/240 = approximately 4 milliseconds between images. On average, when estimating SAT, the video analysis will be off by about two milliseconds per frame, compared with about 16 milliseconds per frame for a 30 Hz recording. The degree of accuracy at 240 fps is simply much greater.
Learn more about Running Form.