title: The impact of sleeping with reduced glycogen stores on immunity and sleep in triathletes.
abstract: OBJECTIVE
  We investigated the effects of a 3-week dietary periodization on immunity and sleep in triathletes.
  
  
  METHODS
  21 triathletes were divided into two groups with different nutritional guidelines during a 3-week endurance training program including nine twice a day sessions with lowered (SL group) or maintained (CON group) glycogen availability during the overnight recovery period. In addition to performance tests, sleep was monitored every night. Systemic and mucosal immune parameters as well as the incidence of URTI were monitored every week of the training/nutrition protocol. Two-ways ANOVA and effect sizes were used to examine differences in dependent variables between groups at each time point.
  
  
  RESULTS
  The SL group significantly improved 10 km running performance (-1 min 13 s, P < 0.01, d = 0.38), whereas no improvement was recorded in the CON group (-2 s, NS). No significant changes in white blood cells counts, plasma cortisol and IL-6 were recorded over the protocol in both groups. The vitamin D status decreased in similar proportions between groups, whereas salivary IgA decreased in the SL group only (P < 0.05, d = 0.23). The incidence of URTI was not altered in both groups. All participants in both groups went to bed earlier during the training program (SL -20 min, CON -27 min, P < 0.05, d = 0.28). In the SL group, only sleep efficiency slightly decreased by 1.1 % (P < 0.05, d = 0.25) and the fragmentation index tended to increase at the end of the protocol (P = 0.06).
  
  
  CONCLUSIONS
  Sleeping and training the next morning regularly with reduced glycogen availability has minimal effects on selected markers of immunity, the incidence of URTI and sleeping patterns in trained athletes.
authors: Research Institute for Sport and Exercise Sciences, Liverpool John Moores University, Byrom Street, Liverpool, L3 3AF, UK. J.B.Louis@ljmu.ac.uk.
authors: Julien
authors: http://orcid.org/0000-0002-9109-0958
authors: J
authors: Louis
authors: Laboratory of Sport, Expertise and Performance, French National Institute of Sport, Expertise and Performance, Paris, France.|Laboratory of Human Motricity, Education, Sport and Health, University of Nice Sophia-Antipolis, Nice, France.
authors: Laurie-Anne
authors: LA
authors: Marquet
authors: Laboratory of Sport, Expertise and Performance, French National Institute of Sport, Expertise and Performance, Paris, France.
authors: Eve
authors: E
authors: Tiollier
authors: Laboratory of Human Motricity, Education, Sport and Health, University of Nice Sophia-Antipolis, Nice, France.|Institut Monégasque de Médecine et Chirurgie du Sport, Monte Carlo, Monaco.
authors: Stéphane
authors: S
authors: Bermon
authors: Laboratory of Sport, Expertise and Performance, French National Institute of Sport, Expertise and Performance, Paris, France.
authors: Christophe
authors: C
authors: Hausswirth
authors: Laboratory of Human Motricity, Education, Sport and Health, University of Nice Sophia-Antipolis, Nice, France.
authors: Jeanick
authors: J
authors: Brisswalter
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D050260:Carbohydrate Metabolism / Q000276:immunology*; D050528:Diet, Carbohydrate-Restricted / Q000379:methods; D004040:Dietary Carbohydrates / Q000276:immunology*; D006003:Glycogen / Q000008:administration & dosage / Q000276:immunology*; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology; D007155:Immunologic Factors / Q000378:metabolism; D008297:Male; D064797:Physical Conditioning, Human / Q000379:methods; D010807:Physical Endurance / Q000276:immunology; D012141:Respiratory Tract Infections / Q000276:immunology / Q000517:prevention & control*; D012890:Sleep / Q000276:immunology*; D013177:Sports; D055815:Young Adult
chemical_list: D004040:Dietary Carbohydrates; D007155:Immunologic Factors; D006003:Glycogen
keywords: Carbohydrate; Dietary manipulation; Endurance training; Immune response; Sleep pattern; Upper respiratory tract infection