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PURPOSE:: No study has examined the response of skeletal muscle AMP-activated protein kinase (AMPK) signaling beyond the first 3 h after an acute exercise bout in humans. The purpose of this study was to assess AMPK signaling in human skeletal muscle immediately after a single bout of moderate-intensity endurance exercise and 3 and 24 h after the exercise bout. METHODS:: We examined AMPK signaling, and protein expression of AMPK alpha, ACC-beta, and nNOSmu in untrained individuals (four females and four males) during the 24-h period after a 60-min bout of moderate-intensity (63 +/- 1% V O2peak) cycling endurance exercise. RESULTS:: AMPK alpha2 activity, AMPK alpha2 Thr phosphorylation, and ACC-beta Ser phosphorylation were increased immediately after exercise. These increases had all returned to basal levels at 3 and 24 h after exercise. Furthermore, an acute bout of exercise did not alter AMPK alpha1, AMPK alpha2, ACC-beta, or nNOSmu protein expression during the 24-h period after exercise. CONCLUSION:: Although an acute bout of exercise elicits increases in AMPK signaling, this alone is not sufficient to induce sustained increases in either AMPK signaling or protein expression during the postexercise period. [ABSTRACT FROM AUTHOR]