title: Postexercise whole-body protein turnover response to three levels of protein intake.
abstract: OBJECTIVE
  This investigation examined the effect of variations in protein intake on whole-body protein turnover (WBPTO) after exercise in endurance-trained males.
  
  
  METHODS
  Five male runners (21.3 +/- 0.3 yr, 179 +/- 2 cm, 70.6 +/- 0.1 kg, 8.7 +/- 0.4% body fat, 70.6 +/- 0.1 VO2peak) participated in a randomized, crossover-design diet intervention, where they consumed either a low- (0.8 g.kg(-1); LP), moderate- (1.8 g.kg(-1); MP), or high-protein (3.6 g.kg(-1); HP) diet for 4 wk. WBPTO (Ra, leucine rate of appearance; NOLD, nonoxidative leucine disposal; and Ox, leucine oxidation) were assessed after a 75-min run at 70% VO2peak after each diet-intervention period.
  
  
  RESULTS
  Leucine Ra (indicator of protein breakdown) and leucine Ox were greater on the HP diet than on the LP diet (Ra, 123.4 +/- 6.9 vs 97.9 +/- 6.0 micromol.kg(-1).h(-1); Ox, 23.9 +/- 0.5 vs 17.0 +/- 0.8 micromol.kg(-1).h(-1), P < 0.05). No differences were noted in NOLD (an indicator of protein synthesis) across diets. Plasma branched chain amino acids (BCAA) at rest were greater for MP and HP than for LP, and nonessential amino acids (NEAA) were greater for LP than MP at rest and greater than MP and HP after exercise.
  
  
  CONCLUSIONS
  Findings from this study show that variations in protein intake can alter plasma amino acid levels and modulate rates of WBPTO after exercise. Additionally, a lower protein intake was associated with decreased rates of WBPTO after exercise.
authors.affiliation: Department of Nutritional Sciences, University of Connecticut, Storrs, CT 06269, USA.
authors.forename: Patricia Courtney
authors.initials: PC
authors.lastname: Gaine
authors.forename: Matthew A
authors.initials: MA
authors.lastname: Pikosky
authors.forename: Douglas R
authors.initials: DR
authors.lastname: Bolster
authors.forename: William F
authors.initials: WF
authors.lastname: Martin
authors.forename: Carl M
authors.initials: CM
authors.lastname: Maresh
authors.forename: Nancy R
authors.initials: NR
authors.lastname: Rodriguez
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000097:blood / Q000378:metabolism; D004044:Dietary Proteins / Q000378:metabolism*; D002149:Energy Intake / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology*; D005081:Exercise Therapy; D006801:Humans; D007930:Leucine / Q000097:blood / Q000378:metabolism; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D013997:Time Factors
chemical_list: D000596:Amino Acids; D004044:Dietary Proteins; D007930:Leucine