Treadmill training does not prevent loss of muscle mass or contractile properties in senescence

Abstract

With aging there is a decline in muscle mass and strength. This study was designed to examine the impact of treadmill training, beginning in late‐middle age and continuing across a 7 mo period when muscle atrophy and functional decline markedly accelerates. 29 mo old rats were divided into 2 groups: half of the animals were exercised on a treadmill for 5 (34T) or 7 mo (36T), while the others maintained normal cage activity (34C and 36C). In situ contractile properties were measured in the Gastrocnemius/plantaris (GAS) and Soleus (SOL) muscles via sciatic nerve stimulation. Mass of the GAS and SOL was lower than young adult (YA) in 34C and 36C. Training had no affect on mass in 34T but decreased mass in 36T vs 36C. GAS tetanic force was lower than YA (12.1 ± 0.9 N/g) in 34T (8.8 ± 0.9 N/g) and 34C (7.1± 1.0 N/g), with no further decline with aging. SOL tetanic force was lower than YA (14.9 ± 0.8 N/g) in 34T (5.4 ± 0.7 N/g) and 34C (5.8 ± 1.0 N/g), with no further decline at 36 mo. In addition, training did not prevent the increase in time to peak force and time to half relaxation seen with aging in controls. In conclusion, treadmill training did not attenuate declining muscle contractile function with aging and may even exacerbate muscle mass decline in senescence.Supported by CIHR and NSERC (Canada).