Muscle AMPKα2 activity, acidosis, and protein synthesis in men and women following resistance exercise

Abstract

Basal muscle protein synthesis is not different between men and women. Skeletal muscle AMP-activated protein kinase (AMPKα2) and acidosis have recently been identified as inhibitors of muscle protein synthesis. The purpose of this study was to determine if there were sex-based differences in muscle AMPKα2 activity, acidosis, and protein synthesis in young men and women following a bout of resistance exercise. We report preliminary data obtained in young subjects (4M, 4F) before and after a bout of resistance exercise. Muscle biopsies were collected from the v. lateralis prior to, immediately post exercise, and at 1hr and 2 hr post exercise. We utilized immunoprecipitation methods to measure AMPKα2 activity. Fractional protein synthetic rate was measured using stable isotope techniques. AMPKα2 activity was not different between men and women at any timepoint (P > 0.05). AMPKα2 activity increased by (25 ± 10 %) immediately post exercise, remained elevated at 1hr (33 ± 13%) and 2hr (33 ± 11%) post exercise (P < 0.05). Femoral vein lactate increased to a similar extent in men (0.8 ± 0.2 to 11.9 ± 1.5 mM) and women (0.7 ± 0.1 to 10.1 ± 0.5 mM) during the resistance exercise bout. Blood pH also decreased during exercise (P > 0.05). Lactate and pH returned to baseline similarly in men and women during post exercise recovery (P < 0.05). Muscle protein synthesis was unchanged from baseline following resistance exercise with no sex-based differences (P > 0.05). We conclude that there are no sex-based differences in muscle AMPKα2 activity, acidosis or protein synthesis immediately following a bout of resistance exercise.