Exercise training increases skeletal muscle strength independent of hypertrophy in older adults aged 75 years and older

Aim: We investigated whether exercise-mediated acquisition of muscle mass and strength would occur in a concurrent manner in older adults. Methods: A total of 152 community-dwelling older adults (young-old aged 65–74 years, old-old aged >75 years) were allocated into either 8-week comprehensive exercise training or the control group. Participants (n = 136) completed all pre- and post-intervention testing visits (young-old n = 73, old-old n = 63). Older adults in exercise groups were subjected to a series of programmed elastic band and free exercises twice per week at three to five sets of 15–20 repetitions. Body composition, skeletal muscle mass, knee strength (extensors and flexors) and gait-related physical function were evaluated as main variables. Results: As expected, muscular mass and knee strength (both extensors and flexors) were inversely correlated with age in the old-old group (all P < 0.001). However, knee extensor strength was the only lower limb component inversely correlated with age in the young-old group (P < 0.043). Knee extensor strength was significantly increased by exercise training in both the young-old and old-old groups (young old P < 0.042, old-old P < 0.011). Training-induced muscle hypertrophy was observed only in the young-old group (P < 0.025). the correlation of knee extensor strength against gait-related physical function was the greatest, followed by knee flexor strength and muscle mass. Conclusions: The present results showed that age-associated strength decline of the knee extensor occurs earlier compared with the knee flexor during the aging process, and exercise training increases muscular strength without significant changes of muscle mass in older adults aged aged ≥75 years. Geriatr Gerontol Int 2019; 19: 265–270.