title: Postexercise Dietary Protein Ingestion Increases Whole-Body Leucine Balance in a Dose-Dependent Manner in Healthy Children.
abstract: Background:Protein ingestion is important in enhancing whole-body protein balance in children. The effect of discrete bolus protein ingestion on acute postexercise recovery has yet to be determined.Objective:This study determined the effect of increasing doses of ingested protein on postexercise whole-body leucine balance in healthy, active children.Methods:Thirty-five children (26 boys, 9 girls; age range: 9-13 y; weight mean ± SD: 44.9 ± 10.6 kg) underwent a 5-d adaptation diet (0.95 g protein ⋅ kg-1⋅ d-1) before performing 20 min of cycling 3 times with a concurrent, primed, constant infusion of [13C]leucine. After exercise, participants consumed an isoenergetic beverage (140 kcal) containing variable amounts of bovine skim-milk protein and carbohydrates (sucrose) (0, 5, 10, and 15 g protein made up with 35, 30, 25, and 20 g carbohydrates, respectively). Blood and breath samples were taken over the 3 h of recovery to determine non-steady state whole-body leucine oxidation (LeuOX) and net leucine balance (LeuBAL).Results:LeuOX(secondary outcome) peaked 60 min after beverage ingestion and demonstrated a relative dose-response over the 3 h of recovery (15 g = 10 > 5 > 0 g;P< 0.001). LeuBAL(primary outcome) demonstrated a dose-response over the 3 h [15 g (24.2 ± 8.2 mg/kg) > 10 g (11.6 ± 4.3 mg/kg) > 5 g (5.7 ± 1.9 mg/kg) > 0 g (-3.0 ± 1.7 mg/kg); allP< 0.01] with all conditions different from zero (allP <0.001).Conclusions:Over the 3-h postexercise period, LeuBALwas negative with carbohydrate ingestion alone; however, the co-ingestion of carbohydrates and 5 g high-quality dietary protein was sufficient to promote a positive postexercise whole-body protein balance in healthy, active children. Moreover, LeuBALincreased in a dose-dependent manner within the protein range studied. Children should consider consuming a source of dietary protein after physical activity to enhance whole-body anabolism. This trial was registered at clinicaltrials.gov as NCT01598935.
authors.affiliation: Child Health & Exercise Medicine Program, Department of Pediatrics, McMaster University, Hamilton, Canada.
authors.forename: Kimberly A
authors.initials: KA
authors.lastname: Volterman
authors.affiliation: Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Canada; and dr.moore@utoronto.ca.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Moore
authors.affiliation: Child Health & Exercise Medicine Program, Department of Pediatrics, McMaster University, Hamilton, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Breithaupt
authors.affiliation: Nestle Research Centre, Lausanne, Switzerland.
authors.forename: Jean-Philippe
authors.initials: JP
authors.lastname: Godin
authors.affiliation: Nestle Research Centre, Lausanne, Switzerland.
authors.forename: Leonidas G
authors.initials: LG
authors.lastname: Karagounis
authors.affiliation: Nestle Research Centre, Lausanne, Switzerland.
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Offord
authors.affiliation: Child Health & Exercise Medicine Program, Department of Pediatrics, McMaster University, Hamilton, Canada.
authors.forename: Brian W
authors.initials: BW
authors.lastname: Timmons
mesh_terms: D000293:Adolescent; D000818:Animals; D002648:Child; D004032:Diet; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004435:Eating; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007930:Leucine / Q000378:metabolism*; D008297:Male; D008892:Milk; D012016:Reference Values; D064133:Sports Nutritional Physiological Phenomena
chemical_list: D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D007930:Leucine
keywords: dietary protein; exercise; leucine metabolism; muscle; recovery