Neuromuscular electrical stimulation increases muscle protein synthesis in elderly, type 2 diabetic men.

Abstract

Physical activity is required to attenuate the loss of skeletal muscle with aging. Short periods of muscle disuse, due to sickness of hospitalization, reduce muscle protein synthesis rates, resulting in rapid muscle loss. The present study investigates the capacity of neuromuscular electrical stimulation (NMES) to increase in vivo skeletal muscle protein synthesis rates in older, type 2 diabetes patients. Six elderly, type 2 diabetic men (70±2 y) were subjected to 60 min of one-legged NMES. Continuous infusions with L-[ring-13C6] phenylalanine were applied, with blood and muscle samples being collected regularly to assess muscle protein synthesis rates in both the stimulated (STIM) and non-stimulated control (CON) leg during 4 h of recovery after NMES. Furthermore, mRNA expression of key genes implicated in the regulation of muscle mass were measured over time in the STIM and CON leg. Muscle protein synthesis rates were greater in the STIM compared with the CON leg during recovery from NMES (0.057±0.008 vs 0.045±0.008% h-1), respectively; P<0.01). Skeletal muscle myostatin mRNA expression in the STIM leg tended to increase immediately following NMES compared with the CON leg (1.63 vs 1.00 fold, respectively; P=0.07) but strongly declined after 2h and 4h of recovery in the STIM leg only. In conclusion, this is the first study to show that NMES directly stimulates skeletal muscle protein synthesis rates in vivo humans. NMES likely represent an effective interventional strategy to attenuate muscle loss in elderly individuals during bed-rest and/or in other disuse states.