title: High dietary protein restores overreaching induced impairments in leukocyte trafficking and reduces the incidence of upper respiratory tract infection in elite cyclists.
abstract: The present study examined whether a high protein diet prevents the impaired leukocyte redistribution in response to acute exercise caused by a large volume of high-intensity exercise training. Eight cyclists (VO2max: 64.2±6.5mLkg(-1)min(-1)) undertook two separate weeks of high-intensity training while consuming either a high protein diet (3gkg(-1)proteinBM(-1)day(-1)) or an energy and carbohydrate-matched control diet (1.5gkg(-1)proteinBM(-1)day(-1)). High-intensity training weeks were preceded by a week of normal-intensity training under the control diet. Leukocyte and lymphocyte sub-population responses to acute exercise were determined at the end of each training week. Self-reported symptoms of upper-respiratory tract infections (URTI) were monitored daily by questionnaire. Undertaking high-intensity training with a high protein diet restored leukocyte kinetics to similar levels observed during normal-intensity training: CD8(+) TL mobilization (normal-intensity: 29,319±13,130cells/μL×∼165min vs. high-intensity with protein: 26,031±17,474cells/μL×∼165min, P>0.05), CD8(+) TL egress (normal-intensity: 624±264cells/μL vs. high-intensity with protein: 597±478cells/μL, P>0.05). This pattern was driven by effector-memory populations mobilizing (normal-intensity: 6,145±6,227cells/μL×∼165min vs. high-intensity with protein: 6,783±8,203cells/μL×∼165min, P>0.05) and extravastating from blood (normal-intensity: 147±129cells/μL vs. high-intensity with protein: 165±192cells/μL, P>0.05). High-intensity training while consuming a high protein diet was associated with fewer symptoms of URTI compared to performing high-intensity training with a normal diet (P<0.05). To conclude, a high protein diet might reduce the incidence of URTI in athletes potentially mediated by preventing training-induced impairments in immune-surveillance.
authors.affiliation: Health and Exercise Sciences Research Group, University of Stirling, Stirling FK9 4LA, Scotland, UK. Electronic address: oliver.witard@stir.ac.uk.
authors.forename: Oliver C
authors.initials: OC
authors.lastname: Witard
authors.affiliation: Department for Health, University of Bath, Bath BA2 7AY, UK.
authors.forename: James E
authors.initials: JE
authors.lastname: Turner
authors.affiliation: Sport & Health Sciences, College of Life and Environmental Sciences, St. Luke's Campus, University of Exeter, Exeter EX1 2LU, Devon, UK.
authors.forename: Sarah R
authors.initials: SR
authors.lastname: Jackman
authors.affiliation: DSM Biotechnology Center, Delft, The Netherlands.
authors.forename: Arie K
authors.initials: AK
authors.lastname: Kies
authors.affiliation: Gatorade Sports Science Institute, Chicago, USA.
authors.forename: Asker E
authors.initials: AE
authors.lastname: Jeukendrup
authors.affiliation: Department of Psychology, University of Amsterdam, The Netherlands; Mannheim Institute of Public Health, Social and Preventive Medicine (MIPH), Mannheim Medical Faculty, University of Heidelberg, Germany.
authors.forename: Jos A
authors.initials: JA
authors.lastname: Bosch
authors.affiliation: Health and Exercise Sciences Research Group, University of Stirling, Stirling FK9 4LA, Scotland, UK.
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Tipton
mesh_terms: D000328:Adult; D056352:Athletes; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects*; D002465:Cell Movement / Q000187:drug effects; D018592:Cross-Over Studies; D004044:Dietary Proteins / Q000627:therapeutic use*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D015994:Incidence; D007962:Leukocytes / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control*; D055815:Young Adult
chemical_list: D004044:Dietary Proteins
keywords: CD8(+) T lymphocytes; Dietary protein; Immune-surveillance; Infection risk; Overtraining