Resistance training and timed essential amino acids protect against the loss of muscle mass and strength during 28 days of bed rest and energy deficit

Authors: BROOKS, NAOMI - STELLENBOSCH UNIVERSITY; CLOUTIER, GREGORY - JM USDA HNRCA -TUFTS UNIV; CADENA, SAMUEL - ACCELERON PHARMA; LAYNE, JENNIFER - FDN INFORMED MED DECISION; NELSEN, CAROL - JM USDA HNRCA -TUFTS UNIV; FREED, ALICIA - JM USDA HNRCA -TUFTS UNIV; ROUBENOFF, RONENN - BIOGEN IDEC, INC.; Castaneda-Sceppa, Carmen

Submitted to: Journal of Applied Physiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2008
Publication Date: 7/1/2008
Citation: Brooks, N., Cloutier, G., Cadena, S., Layne, J., Nelsen, C., Freed, A., Roubenoff, R., Castaneda-Sceppa, C. 2008. Resistance training and timed essential amino acids protect against the loss of muscle mass and strength during 28 days of bed rest and energy deficit. Journal of Applied Physiology. 105:241-248.

Interpretive Summary: Space flight and bed rest (BR) result in losses of muscle mass and strength. Resistance training (RT) and amino acid (AA) supplementation are potential countermeasures to minimize these losses. However, it is unknown if timing of supplementation with exercise can optimize benefits, particularly with energy deficit. We examined the effect of these countermeasures on body composition, strength, and insulin levels in 31 men during bed rest followed by active recovery. Subjects were randomly assigned to: essential AA supplementation; RT with AA given 3h after training; or RT with AA given 5min prior to training. Energy intake was reduced. Mid-thigh muscle area declined the greatest with BR for the AA group and the least with the RT group given AA 5min prior to training. Similarly, greatest losses in lower body muscle strength were seen in the AA group. These were attenuated in the exercising groups. Fat mass and mid-thigh intramuscular fat increased after BR in the AA group, and decreased in the RT and AART groups. Muscle mass and strength returned toward baseline after recovery but the AA group showed the lowest re-gains. Combined resistance training with AA supplementation pre- or post-exercise attenuated the losses in muscle mass and strength compared to AA supplement alone during BR and energy deficit. These data support the efficacy of combined AA and RT as a countermeasure against muscle wasting due to low gravity.

Technical Abstract: Space flight and bed rest (BR) result in losses of muscle mass and strength. Resistance training (RT) and amino acid (AA) supplementation are potential countermeasures to minimize these losses. However, it is unknown if timing of supplementation with exercise can optimize benefits, particularly with energy deficit. We examined the effect of these countermeasures on body composition, strength, and insulin levels in 31 men (ages 31-55 y) during BR (28-d) followed by active recovery (14-d). Subjects were randomly assigned to: essential AA supplementation (AA, n=7); RT with AA given 3h after training (RT, n=12); or RT with AA given 5min prior to training (AART, n=12). Energy intake was reduced by 8'''6%. Mid-thigh muscle area declined with BR for the AA>RT>AART groups: (-11, -3, -4%; p=0.05). Similarly, greatest losses in lower body muscle strength were seen in the AA group (-22%). These were attenuated in the exercising groups [RT (-8%) and AART (-6%; p<0.05)]. Fat mass and mid-thigh intramuscular fat increased after BR in the AA group (+3% and +14%, respectively), and decreased in the RT (-5% and -4%) and AART groups (-1 and -5%; p=0.05). Muscle mass and strength returned toward baseline after recovery but the AA group showed the lowest re-gains. Combined resistance training with AA supplementation pre- or post-exercise attenuated the losses in muscle mass and strength by ~2/3 compared to AA supplement alone during BR and energy deficit. These data support the efficacy of combined AA and RT as a countermeasure against muscle wasting due to low gravity.