Impairment of neuromuscular propagation during human fatiguing contractions at submaximal forces.

摘要: 1. The purpose of the study was to examine dependence neuromuscular propagation impairment on level isometric force sustained endurance limit. task involved human volunteers sustaining a submaximal abduction with index finger by activating first dorsal interosseous muscle as long possible. 2. at one three levels (20, 35 or 65% maximum) increasing motor unit activity, indicated electromyogram (EMG), during fatiguing contraction. Although EMG increased contraction, significantly less than maximum limit for all subjects (deficit 19-55% maximum). This deficit inversely related force. 3. voluntary contraction and twitch forces were reduced following As EMG, degree reduction greatest who low target forces. 4. caused 12-23% decline in M wave amplitude, 33-51% increase duration, no change area. which is an impairment, among 5. mean power frequency decreased similar amount (50-57%) groups subjects. 6. A model representing interaction processes that enhance impair developed explain recovery contractions different 7. We conclude fatigue experienced subject when value does involve propagation. factor limits excitation submaximal, contributes diminished capability end task.