title: The effect of an amino acid beverage on glucose response and glycogen replenishment after strenuous exercise.
abstract: OBJECTIVE
  We previously reported that an amino acid mixture (AA) was able to lower the glucose response to an oral glucose challenge in both rats and humans. Increased glucose uptake and glycogen storage in muscle might be associated with the faster blood glucose clearance. We therefore tested the effect of two different doses of AA provided with a carbohydrate supplement on blood glucose homeostasis and muscle glycogen replenishment in human subjects after strenuous aerobic exercise.
  
  
  METHODS
  Ten subjects received a carbohydrate (1.2 g/kg body weight, CHO), CHO/HAA (CHO + 13 g AA), or CHO/LAA (CHO + 6.5 g AA) supplement immediately and 2 h after an intense cycling bout. Muscle biopsies were performed immediately and 4 h after exercise.
  
  
  RESULTS
  The glucose responses for CHO/HAA and CHO/LAA during recovery were significantly lower than CHO, as was the glucose area under the curve (CHO/HAA 1259.9 ± 27.7, CHO/LAA 1251.5 ± 47.7, CHO 1376.8 ± 52.9 mmol/L 4 h, p < 0.05). Glycogen storage rate was significantly lower in CHO/HAA compared with CHO, while it did not differ significantly between CHO/LAA or CHO (CHO/HAA 15.4 ± 2.0, CHO/LAA 18.1 ± 2.0, CHO 21.5 ± 1.4 µmol/g wet muscle 4 h). CHO/HAA caused a significantly higher insulin response and a greater effect on mTOR and Akt/PKB phosphorylation compared with CHO. Phosphorylation of AS160 and glycogen synthase did not differ across treatments. Likewise, there were no differences in blood lactate across treatments.
  
  
  CONCLUSIONS
  The AA lowered the glucose response to a carbohydrate supplement after strenuous exercise. However, it was not effective in facilitating subsequent muscle glycogen storage.
authors.affiliation: Department of Kinesiology and Health Education, Exercise Physiology and Metabolism Laboratory, University of Texas at Austin, Austin, TX, USA, 33453189@qq.com.
authors.forename: Bei
authors.initials: B
authors.lastname: Wang
authors.forename: Zhenping
authors.initials: Z
authors.lastname: Ding
authors.forename: Wanyi
authors.initials: W
authors.lastname: Wang
authors.forename: Jungyun
authors.initials: J
authors.lastname: Hwang
authors.forename: Yi-Hung
authors.initials: YH
authors.lastname: Liao
authors.forename: John L
authors.initials: JL
authors.lastname: Ivy
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000008:administration & dosage / Q000494:pharmacology*; D001628:Beverages; D001786:Blood Glucose / Q000378:metabolism*; D004040:Dietary Carbohydrates / Q000008:administration & dosage / Q000494:pharmacology; D019587:Dietary Supplements; D015444:Exercise; D005260:Female; D020690:GTPase-Activating Proteins / Q000378:metabolism; D006003:Glycogen / Q000378:metabolism*; D006801:Humans; D007328:Insulin / Q000378:metabolism; D008297:Male; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism* / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism
chemical_list: D000596:Amino Acids; D001786:Blood Glucose; D004040:Dietary Carbohydrates; D020690:GTPase-Activating Proteins; D007328:Insulin; C518767:TBC1D4 protein, human; D006003:Glycogen; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases