title: Beneficial effects of resistance exercise on glycemic control are not further improved by protein ingestion.
abstract: OBJECTIVE
  To investigate the mechanisms underpinning modifications in glucose homeostasis and insulin sensitivity 24 h after a bout of resistance exercise (RE) with or without protein ingestion.
  
  
  METHODS
  Twenty-four healthy males were assigned to a control (CON; n = 8), exercise (EX; n = 8) or exercise plus protein condition (EX+PRO; n = 8). Muscle biopsy and blood samples were obtained at rest for all groups and immediately post-RE (75% 1RM, 8×10 repetitions of leg-press and extension exercise) for EX and EX+PRO only. At 24 h post-RE (or post-resting biopsy for CON), a further muscle biopsy was obtained. Participants then consumed an oral glucose load (OGTT) containing 2 g of [U-¹³C] glucose during an infusion of 6, 6-[²H₂] glucose. Blood samples were obtained every 10 min for 2 h to determine glucose kinetics. EX+PRO ingested an additional 25 g of intact whey protein with the OGTT. A final biopsy sample was obtained at the end of the OGTT.
  
  
  RESULTS
  Fasted plasma glucose and insulin were similar for all groups and were not different immediately post- and 24 h post-RE. Following RE, muscle glycogen was 26±8 and 19±6% lower in EX and EX+PRO, respectively. During OGTT, plasma glucose AUC was lower for EX and EX+PRO (75.1±2.7 and 75.3±2.8 mmol·L⁻¹∶120 min, respectively) compared with CON (90.6±4.1 mmol·L⁻¹∶120 min). Plasma insulin response was 13±2 and 21±4% lower for EX and CON, respectively, compared with EX+PRO. Glucose disappearance from the circulation was ∼12% greater in EX and EX+PRO compared with CON. Basal 24 h post-RE and insulin-stimulated PAS-AS160/TBC1D4 phosphorylation was greater for EX and EX+PRO.
  
  
  CONCLUSIONS
  Prior RE improves glycemic control and insulin sensitivity through an increase in the rate at which glucose is disposed from the circulation. However, co-ingesting protein during a high-glucose load does not augment this response at 24 h post-exercise in healthy, insulin-sensitive individuals.
authors.affiliation: School of Sport and Exercise Sciences, University of Birmingham, Birmingham, United Kingdom.
authors.forename: Leigh
authors.initials: L
authors.lastname: Breen
authors.forename: Andrew
authors.initials: A
authors.lastname: Philp
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Shaw
authors.forename: Asker E
authors.initials: AE
authors.lastname: Jeukendrup
authors.forename: Keith
authors.initials: K
authors.lastname: Baar
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Tipton
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D015153:Blotting, Western; D004044:Dietary Proteins / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D005951:Glucose Tolerance Test; D006003:Glycogen / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D007328:Insulin / Q000097:blood; D008297:Male; D009132:Muscles / Q000378:metabolism; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D004044:Dietary Proteins; D007328:Insulin; D011506:Proteins; D006003:Glycogen