Both aging and exercise training alter the rate of recovery of neuromuscular performance of male soleus muscles.

Abstract

It is known that both exercise and aging influence neuromuscular performance; however their effects on post-exercise recovery are largely unknown. To examine how exercise training and aging might affect post-exercise recovery, the function of muscles taken from young, and aged male rats assigned to exercise, or control conditions was assessed with ex vivo procedures using indirect (nerve endings), and direct (sarcolemma) stimulation at different times (Initial, Final min of, and Recovery i.e. 1min post, from 5min of stimulation). Results revealed that initially, strength of indirectly stimulated young, male muscles was significantly (P = 0.05) greater than aged ones, but after continuous stimulation, aged and young muscles displayed similar strength, and controls showed more strength than trained muscles (P = 0.02). All groups except young controls exhibited significant recovery with 1min of rest (P = 0.03). Compared to indirect stimulation, direct stimulation resulted in greater peak tension at each time point examined (P < 0.05); young muscles again were stronger than aged ones initially (P = 0.003), but not by the conclusion of stimulation (P = 0.20). One min following the direct stimulation protocol, no significant recovery was observed by any of the four treatment groups. These data indicate that motor neurons limit neuromuscular function, and that the effects of fatigue are more severe during stimulation of young, compared to aged muscle. Finally, results presented here indicate that age and training status do interact to influence post-exertional recovery, at least among male neuromuscular systems.