Greater muscle protein synthesis and mitochondrial biogenesis during sprint interval training in males compared with females (702.2)

Improvement in endurance exercise performance in adult humans following sprint interval training (SIT) has been attributed to mitochondrial (mito) biogenesis. However, this conclusion has been inferred from mito biogenic signaling, and not synthesis of new mito protein. Muscle protein synthesis (MPS) and mito biogenic responses to SIT have not been measured, nor have sex‐specific responses. We hypothesized that males and females would have similar rates of MPS, mito biogenesis, and overall individual protein synthetic rates after 9 sessions of SIT. 21 healthy adults (11 male, 10 female, 23±1 years, body mass index: 22.8±0.6 kg/m 2 ; mean±SE) were orally administered deuterium oxide (D 2 O) for measurements of protein synthetic rates for 4 weeks while completing SIT. Maximal oxygen uptake increased (males from 43.4±2.1 to 44.0±2.3; females from 39.5±0.9 to 42.5±1.3 ml/kg/min; P =0.002) following SIT. MPS was greater in males compared with females in the mixed (150%; P <0.001), cytosolic (135%; P =0.038), and mito (135%; P =0.056) fractions. Kinetic proteomics identified 60 proteins that responded differently to SIT between the sexes ( P <0.05); all were greater in males. For the first time, we document greater MPS and mito biogenesis in response to SIT in males compared with females, and present the first data describing the synthetic response of individual proteins in humans during exercise training. Grant Funding Source : Supported by the Office of Naval Research (N00014‐10‐1‐0247)