Parisi Speed School Coaches must understand the biomechanics of speed. Here is an organized biomechanical breakdown of sprinting. While there are more considerations in the biomechanics of the joints and main muscle actions, coaches will have more success improving the speed of their athletes if they understand the role of the primary joint actions and muscles while sprinting.
Additionally, Parisi Coaches are expected to be able to insert key and auxiliary exercises into classes to promote the proper biomechanics of speed. Often these exercises are corrective in nature and translate into improved sprinting and running form.
Sprint speed comes from primarily three joint actions: ankle extension, hip flexion, and hip extension.
Other important joint actions are shoulder flexion, shoulder extension, ankle dorsiflexion, pelvic and shoulder rotation.
Role of the Foot
- The muscles/tendons of the foot arch come into play when the foot makes contact with the ground.
- When upright sprinting, the foot hits the ground supinated and then rolls into pronation.
- The force is absorbed and then stored when the foot pushes off the ground
- Foot strength is very important, and shoes can affect foot performance.
- The iliopsoas, pectineus, rectus femoris, and lower abs are used throughout hip flexion
- They are put on an eccentric stretch as the body moves in front of the leg.
- These muscles are used to explosively accelerate the thigh forward.
- The thigh is stopped by eccentric tension in the hamstring and gluteus as the shin swings out in front of the hips.
Ankle Plantar Flexion
- The calf muscles are the key muscles involved.
- If the quad is active, the athlete is leaping, not running.
- The quad works isometrically here to keep the knee slightly bent.
- Gastrocnemius is more important in sprints versus the soleus which is key to distance running (fast twitch vs. slow twitch).
- The Achilles tendon stores and releases elastic energy, which is created by isometrically contracting the calves during the sprint.
- Once the leg is extended during running, the hamstrings and gluteus maximus “rip” the leg back and down.
- The faster this “rip back and down” occurs, the more force that is generated when the foot touches down.
- In turn, the more force at touchdown, the more tension that can be used for the next push off.
- Once the foot is in full contact with the ground, the hamstring and glute relax for the hip to flex.
- The forward drive of the arm uses the anterior deltoid and the upper pectorals.
- The forward motion is stopped by the eccentric contraction of the posterior deltoid, long head triceps, latissimus dorsi, and teres major.
- The arm action mimics hip joint action in terms of range of motion.
- This becomes powerful when coupled with elbow extension.
- The arm is powerfully brought back into place with a greater load on the leg muscles.
- Involves the posterior deltoid, latissimus dorsi, and the long head of the triceps.
- This motion is not very strong in distance running.
- Occurs with a concentric contraction of the triceps.
- The long head of the tricep tenses eccentrically to stop forward arm drive.
- The 2 other heads of the triceps tense with elbow flexion during the forward arm drive.
- All 3 heads of the triceps contract to whip the arm back for greater push off force.
- Then the long head of the triceps and posterior deltoid raise the elbow up behind the body.
- The elbow needs to be flexed and held at 90° at the forward drive.
- This is performed by the biceps, brachialis, and brachioradialis.
- Arm action described above helps to keep the shoulders square.
- The internal and external obliques and erector spinae stabilize rotation.
- When these core muscles are strong, they stabilize the shoulder and pelvic girdle.
- The hip abductors provide lateral stability.
- The hip abductors assist is stabilizing the and outside of the knee.
- The hip adductors help to initiate knee drive and stop lateral thigh drift.
- The ilium naturally undulate and oscillate with each stride. This pelvic movement is harmonically synchronized with the shoulder axis. A skilled coach should be able to notice if the pelvis is out of rhythm with the shoulder axis.
- Pelvic control is managed through dynamic pelvic floor and core muscular stabilization.
- The upper trapezius, levator scapula, and rhomboids are responsible for moving the shoulder up, down, forward, and back.
- Shoulder elevation and retraction assist in producing ideal arm movement and correct upper body posture.
- Athlete needs to avoid rounded shoulders as it limits arm action.
- Rounded posture is often the cause of the arms crossing the body.
- The lower abdominal, lower back, and pelvic floor muscles control the pelvis position.
- The correct amount of pelvic tilt will assist the athlete when sprinting.
- When the pelvic position is neutral or has slight posterior rotation, the hip flexors are put more on stretch and help to facilitate greater hamstrings and glute complex activation.
- The knee drive is also higher when the pelvis is neutral or achieves slight posterior rotation.
- Hip flexor flexibility is an important factor. If the hip flexors are tight, they pull the pelvis forward which leads to forward lean.