Leucine preserves muscle and strength and enhances recovery following bed rest

Abstract

Reduced mechanical loading is a hallmark of hospitalization and space flight, and contributes to a rapid decrease in muscle mass and functional performance. Mechanistically, these changes are mediated by a 30% reduction in the anabolic response to regular meals. If the ability to exercise is compromised, nutritional interventions represent one of the few viable alternatives. To this end, we added leucine (0.06 g · kg lean mass · meal−1; LEU) to the meals (containing 0.9 g protein · kg · day−1) served to adults (45–60 y) during 14 d bed rest. Our goal was to reduce the loss of muscle mass and function and facilitate recovery during 7 d of rehabilitation. During bed rest, control subjects (CON) lost 3‐ times more total lean body mass than LEU (CON: −3021 ± 400 g vs. LEU: −966 ± 264 g; p=0.001). Following rehabilitation, lean mass deficits persisted in CON while LEU returned to near pre‐bed rest values (CON: −1746 ± 303 g; LEU: −140 ± 367 g). The loss of isometric knee extensor peak torque was also three times greater in CON (−20.3 ± 6.8%) vs. LEU (−7.0 ± 2.5%; p=0.07). Changes in knee extensor total work during a 20 repetition isokinetic endurance test at 180° · s−1 followed a similar pattern (CON: −18.0 ± 7.4% vs. LEU: −5.3 ± 2.8%; p=0.08). These preliminary findings indicate that supplementing regular meals with a small amount of leucine attenuates the loss of muscle mass and function typically associated with bed rest and facilitates recovery.Grant Funding Source : NSBRI