title: Effect of dietary protein content during recovery from high-intensity cycling on subsequent performance and markers of stress, inflammation, and muscle damage in well-trained men.
abstract: Nutrition is an important aspect of recuperation for athletes during multi-day competition or hard training. Post-exercise carbohydrate is likely to improve recovery, but the effect of protein is equivocal. The objective of this study was to determine the effect of post-exercise dietary protein content imposed over a high-carbohydrate background on subsequent performance. Using a crossover design, 12 cyclists completed 3 high-intensity rides over 4 days. Day 1 comprised 2.5 h intervals, followed by repeat-sprint performance tests on days 2 (15 h post) and 4 (60 h post), interspersed with a rest day. During 4 h recovery on days 1 and 2, cyclists ingested either 1.4 g.kg(-1).h(-1) carbohydrate, 0.7 g.kg(-1).h(-1) protein and 0.26 g.kg(-1).h(-1) fat (protein-enriched) or 2.1 g.kg(-1).h(-1) carbohydrate, 0.1 g.kg(-1).h(-1) protein, and equal fat (control). At other times, cyclists ingested a standardized high-carbohydrate diet. Anabolism was gauged indirectly by nitrogen balance, stress and inflammation via cortisol and cytokines, skeletal-muscle membrane disruption by creatine kinase, and oxidative stress by malonyl dealdehyde. Sprint mean power was not clearly different on day 2 (0.0%; 95%CL: +/-3.9%), but on day 4 it was 4.1% higher (+/-4.1%) in the protein-enriched condition relative to control. Reduced creatine kinase was possible (26%; +/-30%) but effects on oxidative stress, inflammatory markers, and cortisol were inconclusive or trivial. Overnight nitrogen balance was positive in the protein-enriched condition on day 1 (249+/-70 mg N.kg FFM(-1); mean+/-SD), but negative (-48+/-26 mg N.kg FFM(-1)) in the control condition. A nutritive effect of post-exercise protein content was not discernible short term (15 h), but a delayed performance benefit (60 h) was observed following protein-enriched high-carbohydrate ingestion.
authors.affiliation: Institute of Food, Nutrition and Human Health, Massey University, New Zealand. d.s.rowlands@massey.ac.nz
authors.forename: David S
authors.initials: DS
authors.lastname: Rowlands
authors.forename: Karin
authors.initials: K
authors.lastname: Rössler
authors.forename: Rhys M
authors.initials: RM
authors.lastname: Thorp
authors.forename: David F
authors.initials: DF
authors.lastname: Graham
authors.forename: Brian W
authors.initials: BW
authors.lastname: Timmons
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Stannard
authors.forename: Mark A
authors.initials: MA
authors.lastname: Tarnopolsky
mesh_terms: D000328:Adult; D001786:Blood Glucose; D002097:C-Reactive Protein / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism / Q000473:pathology; D004044:Dietary Proteins / Q000008:administration & dosage*; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000178:diet therapy / Q000276:immunology / Q000473:pathology; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D015850:Interleukin-6 / Q000097:blood; D019344:Lactic Acid / Q000097:blood; D008297:Male; D018482:Muscle, Skeletal / Q000276:immunology / Q000473:pathology / Q000502:physiology*; D009220:Myositis / Q000178:diet therapy* / Q000276:immunology / Q000473:pathology; D009584:Nitrogen / Q000097:blood; D018384:Oxidative Stress / Q000502:physiology*; D020127:Recovery of Function / Q000502:physiology; D013312:Stress, Physiological / Q000178:diet therapy*; D014409:Tumor Necrosis Factor-alpha / Q000097:blood
chemical_list: D001786:Blood Glucose; D004044:Dietary Proteins; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D019344:Lactic Acid; D002097:C-Reactive Protein; D009584:Nitrogen; D006854:Hydrocortisone