Leucine supplementation partially preserves neuromuscular activation during bed rest (1103.5)

Abstract

We examined the effect of leucine supplementation on neuromuscular activation of sub‐maximal and maximal voluntary muscle contraction (MVC) in middle‐aged adults during 14 days of bed rest (BR). Participants (n = 10, 50.4 ± 1.0 y) in this randomized, double‐blind control 14 day BR study were assigned to a leucine (LEU, 0.06 g∙kg∙meal‐1 leucine) or control (CON) group. Surface electromyography (EMG) and torque were recorded from the vastus lateralis muscle during isometric knee extension at 20% (10s) and at 50%, 80% and 100% MVC (5s each) pre‐post BR and analyzed for root mean square (RMS) and median frequency (MF) EMG. Following BR, MVC (p < 0.001) decreased in both groups with no difference between groups. RMS EMG during 100% MVC decreased in CON post‐BR (p < 0.05), but was maintained in LEU and no difference in MF EMG pre‐post BR for either group (p > 0.05). Despite the decrease in MVC in both groups, CON RMS EMG was higher post‐BR during all sub‐maximal contractions while LEU RMS EMG did not change at 20% and was lower at 50% and 80% MVC post‐BR. Leucine may facilitate neuronal protective mechanisms that preserve motor neuron excitability and attenuate strength loss during prolonged physical inactivity.Grant Funding Source: Supported by NSBRI NNJ08ZSA002N, NIA P30 AG024832, NIH 1UL1RR029876‐01