The influence of prolonged strength training upon muscle and fat in healthy and chronically diseased older adults.

Abstract

Physical muscle function and brain hippocampus size declines with age, accelerating after the age of 60. Strength training over a few months improves physical function, but less is known about how long-term strength training affects physical function and hippocampus volume. Therefore, we aimed to investigate the effect of 1-year strength training of two different intensities upon muscle mass, function, and hippocampus volume in retirement-age individuals. In this multidisciplinary randomized controlled trial (clinicaltrials.gov: NCT02123641), participants were allocated to either a) supervised, heavy resistance training (HRT, n=149, 3/wk), b) moderate intensity resistance training (MIT, n=154, 3/wk) or c) non-exercise activities (CON, n=148). 451 participants were randomized (62-70yrs., women 61%, ≈80% with a chronic medical disease) and 419 were included in the intention-to-treat analysis (n=143, 144 and 132; HRT, MIT and CON). Changes in muscle power (primary outcome), strength and size, physical function, body composition, hippocampus volume and physical/mental well-being were analyzed. Of the participants (HRT+MIT), 83% completed training at least 2/week. Leg extensor power was unchanged in all groups, but strength training had a positive effect on isometric knee extensor strength in both groups, whereas an increased muscle mass, cross-sectional area of vastus lateralis muscle, a decreased whole-body fat percentage, visceral fat content and an improved mental health (SF-36) occurred in HRT only. Further, chair-stand performance improved in all groups, whereas hippocampus volume decreased in all groups over time with no influence of strength training. Together, the results indicate that leg extensor power did not respond to long-term supervised strength training, but this type of training in a mixed group of healthy and chronically diseased elderly individuals can be implemented with good compliance and induces consistent changes in physiological parameters of muscle strength, muscle mass and abdominal fat.