The role of myostatin on skeletal muscle energy metabolism during rest and exercise

Myostatin (Mst) regulates skeletal muscle mass and adipogenesis, but its role in regulating metabolism and physical performance is unknown. We investigated three mouse models: Mst overexpressing transgenic [TG]; Mst knock‐out [KO]; wild type [WT]. Male (1 yr) mice were fed a regular (R), low carb (LC), high carb (HC) or high fat (HF) diet for 6 wks. Maximal (MS) and critical (CS) running speed and ‘work capacity’ (W’) were determined using a treadmill at 5% incline. Results were allometrically scaled for body mass. Calorific intake was not different among diets. Compared to R, body mass was lower all animals in LC (5–8%; P<0.05), but in HC was 9% lower only in KO (P<0.05). During HF body mass was 41% greater in TG than WT (P<0.05). MS was faster among TG animals, especially in LC diet (TG=50±2; WT=40±1; KO=35±1 m/min; P<0.05), and was slower in KO. Also, CS was slower in TG than WT (P<0.05), but only during HC and HF diets. W’ was independent of diet but significantly greater in TG (TG=41±10 m; WT=25±5 m; KO=18±5; P=0.012). The results are consistent with a metabolic regulatory role of Mst, where overexpression results in a greater reliance on â‐oxidation and a reduced glycogenolytic rate. Supported by U54RR022776, SC1GM089648‐01A1.