Age-related reductions in the estimated numbers of motor units are minimal in the human soleus

摘要: The documented impact of contractile level on decomposition-enhanced spike-triggered averaging motor unit number estimates (MUNEs) in young adults demonstrates the importance selecting an objective contraction intensity that yields most representative MUNE for a given muscle. Whether same would be ideal altered system (e.g., by aging or disease) has yet to examined. Thus, main purpose this study was compare effects MUNEs from soleus muscle ( approximately 27 years) and old 75 men. Using averaging, surface intramuscular electromyographic signals were collected during range submaximal isometric plantar-flexion contractions (threshold, 10%, 20%, 30% maximum voluntary contraction; MVC). Five calculated, one each four intensities ensemble derived all MUs collected. Although decreased similarly with increased effort both groups, not significantly reduced men compared Consequently, extrapolated 15% MVC old. results suggest that, soleus, use across age groups is valid comparison.