Human servo responses to load disturbances in fatigued muscle.

Short and long latency EMG responses to muscle stretch and shortening were investigated in the triceps brachii muscle of 16 human subjects during a fatiguing isometric contraction. Increased amplitude reflex responses to stretch, and accentuated reductions in EMG in response to shortening, were evident as fatigue progressed in the majority of subjects. These changes indicate internal compensatory adjustments in the nervous system offsetting the deleterious mechanical effects of muscular fatigue.