Long-term mild endurance exercise effects on the age-associated evolution of hindlimb muscle characteristics in...

The purpose of the study was to describe the effects of long-term, mild daily exercise on age-associated neuromuscular changes in the Syrian hamster. Daily treadmill exercise (for 26 weeks) was administered throughout a portion (25-37%) of the life span (70-100 weeks), beginning at an age of 4 months, during which period body and muscle weights plateau and subsequently decline. Non-exercised (NEX) animals showed an increase in body weight (20%) until 7 months of age, which subsequently declined with the attainment of late adulthood to values not different from 4-month-old controls (Y) by 10.5 months. Gastrocnemius muscles were atrophied, showed twitch potentiation when stimulated in situ, and contained more type I fibers compared to young controls. Hamsters exercised from 4 to 10.5 months of age (EX) showed elevated body weights, and gastrocnemius muscles showed attenuated atrophy (muscle weight and fiber size), lack of twitch potentiation, and a significantly reduced PFK/CS enzyme ratio. Hamsters exercised only until 7 months were similar to NEX group by 10.5 months of age. Mild daily exercise, maintained throughout adult life into early senescence, attenuates muscle atrophy and promotes adaptive enzymatic changes in atrophying muscles.