Effects of 20 days of bed rest and concomitant resistance training on basal energy expenditure and body composition

The purpose of this study was to investigate the effects of prolonged bed rest and concomitant resistance training on basal energy expenditure (BEE) and body composition. Nine young male subjects underwent 20 days of bed rest. Five participants practiced isometric resistance training during the bed rest period (BR+TR), and four participants underwent bed rest alone (BR). The Douglas bag method was used to measure BEE on days 0, 1, 4, 10, and 20. BEE decreased by 8.8% until day 10 and 15.9% until day 20 for the BR group, while it remained in the initial level (+1.2%) for the BR+TR group up to day 10, but decreased by 8.4% until day 20, respectively. Fat-free mass decreased during the bed rest period by 2.5% for the BR group and 1.7％ for the BR+TR groups. The percent decrease in BEE adjusted by body weight after 20 days of bed rest for the BR group was considered equivalent to average decreases of 10 or more years of aging. Minimal resistance training was effective against deleterious effects of bed rest on BEE in the short term, but was insufficient in the long term.