AMPK activation is fiber type specific in human skeletal muscle: Effects of exercise and short-term exercise training

Abstract

AMP-activated protein kinase (AMPK) has been extensively studied in whole muscle biopsy samples of humans, yet the fiber type-specific expression and/or activation of AMPK is unknown. We examined basal and exercise AMPK-α Thr172 phosphorylation and AMPK subunit expression (α1, α2, and γ3) in type I, IIa, and IIx fibers of human skeletal muscle before and after 10 days of exercise training. Before training basal AMPK phosphorylation was greatest in type IIa fibers (P < 0.05 vs. type I and IIx), while an acute bout of exercise increased AMPK phosphorylation in all fibers (P < 0.05), with the greatest increase occurring in type IIx fibers. Exercise training significantly increased basal AMPK ph..