Joint Torque and Mechanical Power of Lower Extremity and Its Relevance to Hamstring Strain during Sprint Running.

Yunjian Zhong,Yu Liu,Weijie Fu,Qing Li,Shutao Wei

doi:10.1155/2017/8927415

Yunjian Zhong, Yu Liu + Show 3 more

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https://doi.org/10.1155/2017/8927415

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Abstract

The aim of this study was to quantify the contributions of lower extremity joint torques and the mechanical power of lower extremity muscle groups to further elucidate the loadings on hamstring and the mechanics of its injury. Eight national-level male sprinters performed maximum-velocity sprint running on a synthetic track. The 3D kinematic data and ground reaction force (GRF) were collected synchronously. Intersegmental dynamics approach was used to analyze the lower extremity joint torques and power changes in the lower extremity joint muscle groups. During sprinting, the GRF during the stance phase and the motion-dependent torques (MDT) during the swing phase had a major effect on the lower extremity movements and muscle groups. Specifically, during the stance phase, torque produced and work performed by the hip and knee muscles were generally used to counteract the GRF. During the swing phase, the role of the muscle torque changed to mainly counteract the effect of MDT to control the movement direction of the lower extremity. Meanwhile, during the initial stance and late swing phases, the passive torques, namely, the ground reaction torques and MDT produced by the GRF and the inertial movement of the segments of the lower extremity, applied greater stress to the hamstring muscles.

Highlights

Sprint running is a cyclical movement of alternate support and flight motions and combination of foot-strike and swing
The stance phase was defined as the phase in which the left foot of an athlete was in contact with the ground (Figure 1)
The external and motion-dependent forces that acted on each segment of the human body had vital effects on the function of joint muscle groups during sprinting

Summary

Introduction

Sprint running is a cyclical movement of alternate support and flight motions and combination of foot-strike and swing. The ability of the lower extremity muscle groups to perform specific work directly affects running speed and in turn interacts with the loading conditions of the muscle itself. Greater motion-dependent torques (MDT; e.g., inertia, Coriolis, and centrifugal forces) will be generated and acted upon each segment when lower extremity joints rapidly alternate between flexion and extension during the swing phase [9]. Torques generated by these external forces play a vital role in affecting the function of the lower extremity muscle groups during sprinting

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