RESISTANCE EXERCISE MAINTAINS SKELETAL-MUSCLE PROTEIN-SYNTHESIS DURING BED REST

Spaceflight results in a loss of lean body mass and muscular strength. A ground-based model for microgravity, bed rest, results in a loss of lean body mass due to a decrease in muscle protein synthesis (MPS). R esistance training is suggested as a proposed countermeasure for space flight-induced atrophy because it is known to increase both MPS and sk eletal muscle strength. We therefore hypothesized that scheduled resis tance training throughout bed rest would ameliorate the decrease in MP S. Two groups of healthy volunteers were studied during 14 days of sim ulated microgravity. One group adhered to strict bed rest (BR; n = 5), whereas a second group engaged in leg resistance exercise every other day throughout bed rest (BREx; n = 6). MPS was determined directly by the incorporation of infused L-[ring-C-13(6)]phenylalanine into vastu s lateralis protein. After 14 days of bed rest, MPS in the BREx group did not change and was significantly greater than in the BR group. Thu s moderate-resistance exercise can counteract the decrease in MPS duri ng bed rest.