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SPRINT ACCELERATION MECHANICS
THE ROLE OF HAMSTRING MUSCLES IN HORIZONTAL GROUND REACTION FORCE PRODUCTION
@jb_morin
Morin JB University of Nice, France Edouard P University of Saint-Etienne, France Gimenez P University of Franche-Comté, France Arnal P University of Saint-Etienne, France Jimenez-Reyes P Catholic University of San Antonio, Murcia, Spain Samozino P University of Savoy, France Mendiguchia J Zentrum Rehab Center, Baranian, Spain Brughelli M Auckland University of Technology, New-Zealand
Survival of the fastest?
Acceleration is the key…
2011 -‐ 2015 Sprint acceleration: importance of Horizontal Force Production
Sprint Instrumented treadmill Track-‐Embedded Force Plates Elite Athletes Med Sci Sport Exerc 2011 Eur J Appl Physiol 2012 Scand J Med Sci Sport 2015 J Biomech In Press
Horizontal GRF / impulse is paramount Vertical / resultant GRF is not « Ratio of Forces » and Hzt Force at high speed higher in top athletes
Higher RF at high, not low speeds…
How to produce High net HZT Force At High running speed??
The « Hip Extensors » hypothesis
Synchronized EMG (2 kHz) and 3D GRF (1 kHz)
Treadmill Sprint Accelerations
2D Motion Knee and Foot
Knee Extensor Hip Extensor Isokinetic Torque
The « Hip Extensors » hypothesis
The « Hip Extensors » hypothesis
Preliminary results…. Paper in preparation
Isokinetic Torque alone NOT correlated to GRF
Muscle activity (EMG) alone: NOT correlated to GRF
Multiple Regressions: FHZT entire acceleration correlated to : Eccentric Hamstring torque
EMG BF during end-of-swing phase FHZT initial acceleration correlated to : Eccentric Hamstring torque
EMG BF during end-of-swing phase
Concentric Glutei torque EMG Glut during end-of-swing phase
Quadriceps…. Contact phase: NS
2D Motion (speed, range of motion) of Knee and Foot: NS
« Prepare and Repair »
Importance of Horizontal GRF (especially at high speed)
What balance between hip extensors and other groups in training?
Hamstring Eccentric Force and Activation: Performance AND Injury Prevention
Associated with: high hip extensors force (Glut in CONC and Ham in ECC) high end-of-swing EMG activity
MERCI !!