HES 319 Lecture Notes - Agonist, Alpha Motor Neuron, Muscle Fatigue
Document Summary
Muscle fatigue can be defined as an activity-related impairment of the physiologic processes that are involved in the production of muscle force. We can study muscle fatigue for different types of muscular activity. Muscle fatigue can be caused by changes in physiological mechanics at many different sites in the neuromuscular system. Blood flow to the muscle supply decreases with muscle force, venous outflow decreases. During sustained submaximal contractions, the force does not change, but the emg from the muscle increases. This is due to an increased neural drive, or neural command, to the muscle that is not translated into changes in force. This suggests that mechanisms distal to the sarcolemma are being altered during fatigue. Muscle fibers begin to fail, therefore there must be increased output from the brain. Muscle fatigue can be caused by failure of neuromuscular transmission. There is a fairly large decrease in the force from repetitive nerve stimulation.