title: Preexercise aminoacidemia and muscle protein synthesis after resistance exercise.
abstract: OBJECTIVE
  We have previously shown that the aminoacidemia caused by the consumption of a rapidly digested protein after resistance exercise enhances muscle protein synthesis (MPS) more than the amino acid (AA) profile associated with a slowly digested protein. Here, we investigated whether differential feeding patterns of a whey protein mixture commencing before exercise affect postexercise intracellular signaling and MPS.
  
  
  METHODS
  Twelve resistance-trained males performed leg resistance exercise 45 min after commencing each of three volume-matched nutrition protocols: placebo (PLAC, artificially sweetened water), BOLUS (25 g of whey protein + 5 g of leucine dissolved in artificially sweetened water; 1 × 500 mL), or PULSE (15 × 33-mL aliquots of BOLUS drink every 15 min).
  
  
  RESULTS
  The preexercise rise in plasma AA concentration with PULSE was attenuated compared with BOLUS (P < 0.05); this effect was reversed after exercise, with two-fold greater leucine concentrations in PULSE compared with BOLUS (P < 0.05). One-hour postexercise, phosphorylation of p70 S6K(thr389) and rpS6(ser235/6) was increased above baseline with BOLUS and PULSE, but not PLAC (P < 0.05); furthermore, PULSE > BOLUS (P < 0.05). MPS throughout 5 h of recovery was higher with protein ingestion compared with PLAC (0.037 ± 0.007), with no differences between BOLUS or PULSE (0.085 ± 0.013 vs. 0.095 ± 0.010%.h(-1), respectively, P = 0.56).
  
  
  CONCLUSIONS
  Manipulation of aminoacidemia before resistance exercise via different patterns of intake of protein altered plasma AA profiles and postexercise intracellular signaling. However, there was no difference in the enhancement of the muscle protein synthetic response after exercise. Protein sources producing a slow AA release, when consumed before resistance exercise in sufficient amounts, are as effective as rapidly digested proteins in promoting postexercise MPS.
authors.affiliation: Sports Nutrition, Australian Institute of Sport, Canberra, ACT, Australia. louise.burke@ausport.gov.au
authors.forename: Louise M
authors.initials: LM
authors.lastname: Burke
authors.forename: John A
authors.initials: JA
authors.lastname: Hawley
authors.forename: Megan L
authors.initials: ML
authors.lastname: Ross
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Moore
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Phillips
authors.forename: Gary R
authors.initials: GR
authors.lastname: Slater
authors.forename: Trent
authors.initials: T
authors.lastname: Stellingwerff
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Tipton
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Garnham
authors.forename: Vernon G
authors.initials: VG
authors.lastname: Coffey
mesh_terms: D000138:Acidosis / Q000097:blood*; D000328:Adult; D000596:Amino Acids / Q000097:blood*; D006801:Humans; D007866:Leg / Q000502:physiology; D007930:Leucine / Q000008:administration & dosage; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage*; D009124:Muscle Proteins / Q000096:biosynthesis*; D018482:Muscle, Skeletal / Q000378:metabolism*; D010766:Phosphorylation; D055070:Resistance Training; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D013549:Sweetening Agents / Q000008:administration & dosage; D013912:Threonine / Q000378:metabolism; D000067816:Whey Proteins
chemical_list: D000596:Amino Acids; D008894:Milk Proteins; D009124:Muscle Proteins; D013549:Sweetening Agents; D000067816:Whey Proteins; D013912:Threonine; D012694:Serine; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D007930:Leucine