Functional recovery from eccentric injury is maintained in sarcopenic mouse muscle.

Background: Eccentric contractions induce muscle damage (EIMD) that compromises muscle function. Poor recovery from EIMD has been suggested to be a contributor to the decline in muscle function evident in sarcopenia, but it is unclear which aspects of muscle function are more susceptible to disruption by EIMD in old versus young muscle. The purpose of this study was to determine the extent of impairment in contractile function (force, fatigue, tetanus and twitch kinetics) during the recovery from EIMD in very old (VO) mice compared to young adult (YA). Methods: Male CB6F1 were obtained from National Institure of Aging colony. VO mice were 29-31 months of age, and YA mice were 7-9 months of age. The plantarflexor muscles were subjected to 20 eccentric contractions Results: There was a greater loss in isometric tetanic force immediately following EIMD in VO compared with YA (-31.6% ± 10.4 vs. -21.7% ± 6.0, Conclusions: Despite clear functional deficits and greater susceptibility to injury, aged sarcopenic muscle exhibited a similar ability to recover contractile function to younger muscle following EIMD. In addition, neither age group showed accelerated muscle fatigue in the recovery phase after EIMD; thus, sarcopenic mouse muscles do not appear to be more susceptible to long-term functional impairment than young healthy muscles.