title: Impact of intensified training and carbohydrate supplementation on immunity and markers of overreaching in highly trained cyclists.
abstract: OBJECTIVE
  To determine effects of intensified training (IT) and carbohydrate supplementation on overreaching and immunity.
  
  
  METHODS
  In a randomized, double-blind, crossover design, 13 male cyclists (age 25 ± 6 years, VO2max 72 ± 5 ml/kg/min) completed two 8-day periods of IT. On one occasion, participants ingested 2 % carbohydrate (L-CHO) beverages before, during and after training sessions. On the second occasion, 6 % carbohydrate (H-CHO) solutions were ingested before, during and after training, with the addition of 20 g of protein in the post-exercise beverage. Blood samples were collected before and immediately after incremental exercise to fatigue on days 1 and 9.
  
  
  RESULTS
  In both trials, IT resulted in decreased peak power (375 ± 37 vs. 391 ± 37 W, P < 0.001), maximal heart rate (179 ± 8 vs. 190 ± 10 bpm, P < 0.001) and haematocrit (39 ± 2 vs. 42 ± 2 %, P < 0.001), and increased plasma volume (P < 0.001). Resting plasma cortisol increased while plasma ACTH decreased following IT (P < 0.05), with no between-trial differences. Following IT, antigen-stimulated whole blood culture production of IL-1α was higher in L-CHO than H-CHO (0.70 (95 % CI 0.52-0.95) pg/ml versus 0.33 (0.24-0.45) pg/ml, P < 0.01), as was production of IL-1β (9.3 (95 % CI 7-10.4) pg/ml versus 6.0 (5.0-7.8) pg/ml, P < 0.05). Circulating total leukocytes (P < 0.05) and neutrophils (P < 0.01) at rest increased following IT, as did neutrophil:lymphocyte ratio and percentage CD4+ lymphocytes (P < 0.05), with no between-trial differences.
  
  
  CONCLUSIONS
  IT resulted in symptoms consistent with overreaching, although immunological changes were modest. Higher carbohydrate intake was not able to alleviate physiological/immunological disturbances.
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK. i.s.svendsen@lboro.ac.uk.
authors.forename: Ida S
authors.identifier: http://orcid.org/0000-0002-3052-1793
authors.initials: IS
authors.lastname: Svendsen
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK.
authors.forename: Sophie C
authors.initials: SC
authors.lastname: Killer
authors.affiliation: Gatorade Sports Science Institute, PepsiCo Global Nutrition R&D, Beaumont Park, Leicester, UK.
authors.forename: James M
authors.initials: JM
authors.lastname: Carter
authors.affiliation: Gatorade Sports Science Institute, PepsiCo Global Nutrition R&D, Beaumont Park, Leicester, UK.
authors.forename: Rebecca K
authors.initials: RK
authors.lastname: Randell
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK.
authors.forename: Asker E
authors.initials: AE
authors.lastname: Jeukendrup
authors.affiliation: School of Sport, Exercise and Health Sciences, Loughborough University, Leicestershire, LE11 3TU, UK.
authors.forename: Michael
authors.initials: M
authors.lastname: Gleeson
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000328:Adult; D001642:Bicycling / Q000502:physiology*; D015415:Biomarkers / Q000097:blood*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000276:immunology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D005221:Fatigue / Q000097:blood / Q000276:immunology; D006801:Humans; D006854:Hydrocortisone / Q000097:blood; D053582:Interleukin-1alpha / Q000097:blood; D053583:Interleukin-1beta / Q000097:blood; D008297:Male; D010807:Physical Endurance / Q000276:immunology* / Q000502:physiology*
chemical_list: D015415:Biomarkers; D004040:Dietary Carbohydrates; D053582:Interleukin-1alpha; D053583:Interleukin-1beta; D000324:Adrenocorticotropic Hormone; D006854:Hydrocortisone
keywords: ACTH; Cortisol; Cytokine; Interleukin; Lymphocyte; Overreaching