AMPK and PGC- α following maximal and supramaximal exercise in men and women: a randomized cross-over study.

We tested the hypothesis that AMPK activation and peroxisome proliferator gamma coactivator 1 alpha (PGC-1 α ) expression are not augmented as exercise intensity (power output) increases from maximal to supramaximal intensities and conducted an exploratory analysis comparing AMPK activation and PGC-1α expression in males and females. Seventeen ( n  = 9 males; n  = 8 females) recreationally active, healthy, young individuals volunteered to participate in the current study. Participants completed work matched interval exercise at 100% (Max) and 133% (Supra) of peak work rate (WRpeak). Intervals were 1 min in duration and participants were prescribed 6 and 8 intervals of Max and Supra, respectively, to equate external work across protocols. PGC-1 α mRNA expression and activation of AMPK (p-ACC) were examined in muscle biopsy samples. Interval WR (watts; W), intensity (%WRpeak) and average HR (bpm), blood lactate (mmol/L) and rating of perceived exertion were all higher (all p  < 0.05) in Supra. Fatigue was greater ( p  < 0.05) in Supra. PGC-1α mRNA expression significantly increased after exercise in Max ( p  < 0.01) and Supra ( p  < 0.01), but was not significantly different ( p  = 0.71) between intensities. A main effect of time (Pre - 0 h) ( p  < 0.01) was observed for p-ACC; however, no effect of intensity ( p  = 0.08) or interaction ( p  = 0.97) was observed. No significant effects of time ( p  = 0.05) intensity ( p  = 0.42), or interaction ( p  = 0.97) were observed for p-AMPK (Thr172). Exploratory sex analysis demonstrated a main effect of sex for p-ACC (greater p-ACC in males; p  < 0.05) but not for p-AMPK or PGC-1 α expression. Our results confirm that AMPK-PGC-1 α signalling is not augmented following supramaximal exercise and provide novel data demonstrating a decrease in AMPK activation (p-ACC) in females compared to men. Trial registration: https://doi.org/10.17605/OSF.IO/U7PX9.