title: Caffeine and performance over consecutive days of simulated competition.
abstract: OBJECTIVE
  Performance improvements after caffeine (CAF) ingestion are well documented when using a 1-d protocol. In numerous competitions such as the Tour de France, Tour de Ski, world championships, and National College Athletic Association championships, athletes compete for several days in a row. To date, no studies have investigated the effects of CAF when competing for consecutive days in a row. This study aimed to investigate the effects of placebo (PLA) and two different CAF doses (3 and 4.5 mg·kg body mass) on performance in a 10-min all-out, cross-country, double poling ergometer test (C-PT) 2 d in a row.
  
  
  METHODS
  Eight highly trained male cross-country skiers (V˙O2max-run, 78.5 ± 1.6 mL·kg·min) participated in the study, which was a randomized, double-blind, PLA-controlled, crossover design. Performance was assessed as distance covered during a 10-min all-out C-PT. Oral ingestion of CAF or PLA was consumed 75 min before the all-out C-PT.
  
  
  RESULTS
  Poling distance was improved after CAF ingestions compared with that after PLA on both days. The improvements on day 1 were 4.0% (90% confidence limits, ±3.3) and 4.0% ± 2.9% for both CAF doses, respectively (P < 0.05), whereas improvements on day 2 were 5.0% ± 3.6% and 5.1% ± 2.8% for CAF3 and CAF4.5, respectively, compared with those for PLA. Improved performance was associated with increased HR, adrenaline concentration, blood lactate concentration, and V˙O2 consumption after CAF ingestion. Furthermore, performance was elevated despite higher creatine kinase concentration and muscular pain at arrival on day 2 for both CAF doses.
  
  
  CONCLUSIONS
  Both CAF doses improved performance in the 10-min all-out C-PT compared with PLA over two consecutive days. Therefore, CAF seems useful for athletes competing over consecutive days despite higher muscle damage occurring after enhanced performance on the first day.
authors.affiliation: 1Department of Physical Performance, Norwegian School of Sport Sciences, Ullevål Stadion, Oslo, NORWAY; and 2Department of Chemical and Biological Working Environment, National Institute of Occupational Health, Oslo, NORWAY.
authors.forename: Hans Kristian
authors.initials: HK
authors.lastname: Stadheim
authors.forename: Matthew
authors.initials: M
authors.lastname: Spencer
authors.forename: Raymond
authors.initials: R
authors.lastname: Olsen
authors.forename: Jørgen
authors.initials: J
authors.lastname: Jensen
mesh_terms: D054874:Athletic Performance / Q000502:physiology*; D002110:Caffeine / Q000008:administration & dosage / Q000494:pharmacology*; D003163:Competitive Behavior; D003402:Creatine Kinase / Q000097:blood; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004837:Epinephrine / Q000097:blood; D005080:Exercise Test; D006339:Heart Rate; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D063806:Myalgia / Q000097:blood; D010101:Oxygen Consumption; D058573:Performance-Enhancing Substances / Q000008:administration & dosage / Q000494:pharmacology*; D015990:Placebo Effect; D012420:Running / Q000502:physiology; D012865:Skiing / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
chemical_list: D058573:Performance-Enhancing Substances; D019344:Lactic Acid; D002110:Caffeine; D003402:Creatine Kinase; D004837:Epinephrine