Date of Graduation


Document Type



Musculo-skeletal injury is a major occupational concern in the modern workforce. To date, the mechanisms responsible for muscle injury are not clearly understood. The objective of this research was to quantify the effect of dynamic parameters such as strain, strain-rate, number of repetitions, and loading cycles in muscle injury. A computer-controlled rodent dynamometer was designed and fabricated at WVU to facilitate the systematic investigation of eccentric-contraction induced muscle injury. An in vivo rodent model was used to study the effects of velocity and continuous versus intermittent loading on the rat plantarflexor group. The experimental results indicated that injury was independent of velocity as a result of intermittent loading; however, injury was not independent of velocity as a result of continuous loading. The dynamic muscle response of the rat plantarflexor group was modeled analytically to distinguish between physiologic and materials fatigue. The results of the experimental and analytical model suggests that muscle fails due to materials fatigue (the result of more than one repetition). The experimental findings also suggest that high muscle output force contributes more to muscle injury than the dynamics of the movement.