Late Life Aerobic Exercise Mitigates Age-related Declines in Physical Function in Male and Female Rats

While lifelong aerobic exercise (AE) is touted to counteract various age-related health detriments, the efficacy of AE initiated late in life remains unknown. PURPOSE: To investigate whether late life AE can reverse age-related physical and muscle decline in rats. METHODS: 52 male (M; n=22) and female (F; n=24) Fischer 344 rats (3- and 21-months) were randomly assigned in sedentary (SED) or exercise (EX) groups, composing 4 experimental groups per sex: Young SED (n=11; 6M, 5F) Young EX (n=12; 6M, 6F), Old SED (n=12; 5M, 7F) and Old EX (n=12; 6M, 6F). Prior to and after training, all animals underwent a maximal treadmill test to assess exercise tolerance (ET). Both trained groups were subjected to treadmill running at 60% maximal speed reached on the treadmill test, 10° incline, 50 min/day, 5 days for 8 weeks. At the end of the experiment, percentage of lean mass (LM%) was assessed via echoMRI and in vivo muscle function by neuromuscular stimulation. RESULTS: Old M animals demonstrated reduced ET than young (Old: 13.6±4.2, Young: 23.7±5.6min; pCONCLUSIONS: AE initiated late in life attenuated age-related declines in physical function across both sexes and was correlated with improvements in body composition. Interestingly, muscle function was improved following AE only in M animals but not in either trained F cohorts, highlighting potential sex-specific mechanisms in which aging deteriorates muscle function.