title: Protein ingestion does not impair exercise-induced AMPK signalling when in a glycogen-depleted state: implications for train-low compete-high.
abstract: The aim of the present study was to test the hypothesis that consuming protein does not attenuate AMPK signalling when exercise is commenced in a glycogen-depleted state. After performing a glycogen-depleting protocol the evening before, the subsequent morning ten active men performed 45 min steady-state cycling at 50 % of peak power output (PPO) followed by an exercise capacity test (1-min intervals at 80 % PPO interspersed with 1-min periods at 40 % PPO). In a repeated measures design, subjects consumed 20 g of a casein hydrolysate solution (PRO) 45 min before exercise, 10 g during and a further 20 g immediately post-exercise, or an equivalent volume of a non-calorie taste matched placebo (PLA). Resting (PRO = 134 ± 29; PLA = 136 ± 28 mmol kg(-1)) and post-exercise muscle glycogen (PRO = 43 ± 16; PLA = 47 ± 18 mmol kg(-1)) was not different (P > 0.05) between trials nor was exercise capacity (PRO = 26 ± 9; PLA = 25 ± 10 min, P > 0.05). Phosphorylation of AMPK(Thr172) increased threefold immediately post-exercise (P < 0.05) and PGC1-mRNA increased sixfold at 3 h post-exercise (P < 0.05), though there were no differences between conditions (P > 0.05). In contrast, there was a trend (P = 0.08) for a divergent response in eEF2(Thr56) phosphorylation such that 1.5 fold increases post- and 3 h post-exercise in PLA were blunted with PRO, thus indicative of greater eEF2 activation. We conclude that athletes who deliberately incorporate training phases with reduced muscle glycogen into their training programmes may consume protein before, during and after exercise without negating signalling through the AMPK cascade.
authors.affiliation: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Tom Reilly Building, Byrom St Campus, Liverpool, L3 3AF, UK.
authors.forename: Conor
authors.initials: C
authors.lastname: Taylor
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Bartlett
authors.forename: Christian Soler
authors.initials: CS
authors.lastname: van de Graaf
authors.forename: Jari
authors.initials: J
authors.lastname: Louhelainen
authors.forename: Vicki
authors.initials: V
authors.lastname: Coyne
authors.forename: Zafar
authors.initials: Z
authors.lastname: Iqbal
authors.forename: Don P M
authors.initials: DP
authors.lastname: Maclaren
authors.forename: Warren
authors.initials: W
authors.lastname: Gregson
authors.forename: Graeme L
authors.initials: GL
authors.lastname: Close
authors.forename: James P
authors.initials: JP
authors.lastname: Morton
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D002364:Caseins / Q000378:metabolism / Q000494:pharmacology*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004326:Drinking; D015444:Exercise; D005080:Exercise Test; D017079:Exercise Tolerance; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D010766:Phosphorylation; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D055815:Young Adult
chemical_list: D002364:Caseins; C486497:PPARGC1A protein, human; D000071248:Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha; D014157:Transcription Factors; C475729:casein hydrolysate; D006003:Glycogen; D055372:AMP-Activated Protein Kinases