Resistance exercise with low glycogen increases p53 phosphorylation and PGC-1α mRNA in skeletal muscle.

Abstract

We determined the effect of reduced muscle glycogen availability on cellular pathways regulating mitochondrial biogenesis and substrate utilization after a bout of resistance exercise. Eight young, recreationally trained men undertook a glycogen depletion protocol of one-leg cycling to fatigue (LOW), while the contralateral (control) leg rested (CONT). Following an overnight fast, subjects completed 8 sets of 5 unilateral leg press repetitions (REX) at 80% 1 Repetition Maximum (1RM) on each leg. Subjects consumed 500mL protein/CHO beverage (20g whey+40g maltodextrin) upon completion of REX and 2h later. Muscle biopsies were obtained at rest and 1 and 4h after REX in both legs. Resting muscle glycogen was higher in the CONT than LOW leg (~384±114 vs 184±36mmolkg(-1) dry wt; P<0.05), and 1h and 4h post-exercise (P<0.05). Phosphorylation of p53(Ser15) increased 1h post-exercise in LOW (~115%, P<0.05) and was higher than CONT at this time point (~87%, P<0.05). p38MAPK(Thr180/Tyr182) phosphorylation increased 1h post-exercise in both CONT and LOW (~800-900%; P<0.05) but remained above rest at 4h only in CONT (~585%, P<0.05; different between legs P<0.05). Peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) mRNA was elevated 4h post-exercise in LOW (~200%, P<0.05; different between legs P<0.05). There were no changes in Fibronectin type III domain-containing protein 5 (FNDC5) mRNA for CONT or LOW legs post-exercise. Undertaking resistance exercise with low glycogen availability may enhance mitochondrial-related adaptations through p53 and PGC-1α-mediated signalling.