title: Repeated double-poling sprint training in hypoxia by competitive cross-country skiers.
abstract: OBJECTIVE
  Repeated-sprint training in hypoxia (RSH) was recently shown to improve repeated-sprint ability (RSA) in cycling. This phenomenon is likely to reflect fiber type-dependent, compensatory vasodilation, and therefore, our hypothesis was that RSH is even more beneficial for activities involving upper body muscles, such as double poling during cross-country skiing.
  
  
  METHODS
  In a double-blinded fashion, 17 competitive cross-country skiers performed six sessions of repeated sprints (each consisting of four sets of five 10-s sprints, with 20-s intervals of recovery) either in normoxia (RSN, 300 m; FiO2, 20.9%; n = 8) or normobaric hypoxia (RSH, 3000 m; FiO2, 13.8 %; n = 9). Before (pre) and after (post) training, performance was evaluated with an RSA test (10-s all-out sprints-20-s recovery, until peak power output declined by 30%) and a simulated team sprint (team sprint, 3 × 3-min all-out with 3-min rest) on a double-poling ergometer. Triceps brachii oxygenation was measured by near-infrared spectroscopy.
  
  
  RESULTS
  From pretraining to posttraining, peak power output in the RSA was increased (P < 0.01) to the same extent (29% ± 13% vs 26% ± 18%, nonsignificant) in RSH and in RSN whereas the number of sprints performed was enhanced in RSH (10.9 ± 5.2 vs 17.1 ± 6.8, P < 0.01) but not in RSN (11.6 ± 5.3 vs 11.7 ± 4.3, nonsignificant). In addition, the amplitude in total hemoglobin variations during sprints throughout RSA rose more in RSH (P < 0.01). Similarly, the average power output during all team sprints improved by 11% ± 9% in RSH and 15% ± 7% in RSN.
  
  
  CONCLUSIONS
  Our findings reveal greater improvement in the performance of repeated double-poling sprints, together with larger variations in the perfusion of upper body muscles in RSH compared with those in RSN.
authors.affiliation: 1Institute of Sport Sciences, University of Lausanne, Lausanne, SWITZERLAND; 2Department of Physiology, Faculty of Biology and Medicine, University of Lausanne, Lausanne, SWITZERLAND; 3Nationellt Vintersport Centrum, Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, SWEDEN; 4Department of Sport Science, University of Wuppertal, Wuppertal, GERMANY; and 5Applied Signal Processing Group, Swiss Federal Institute of Technology, Ecole Polytechnique Fédérale de Lausanne, Lausanne, SWITZERLAND.
authors.forename: Raphael
authors.initials: R
authors.lastname: Faiss
authors.forename: Sarah
authors.initials: S
authors.lastname: Willis
authors.forename: Dennis-Peter
authors.initials: DP
authors.lastname: Born
authors.forename: Billy
authors.initials: B
authors.lastname: Sperlich
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Vesin
authors.forename: Hans-Christer
authors.initials: HC
authors.lastname: Holmberg
authors.forename: Grégoire P
authors.initials: GP
authors.lastname: Millet
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D003163:Competitive Behavior / Q000502:physiology*; D004311:Double-Blind Method; D004576:Electromyography; D005260:Female; D006801:Humans; D000860:Hypoxia; D008297:Male; D018482:Muscle, Skeletal / Q000098:blood supply / Q000378:metabolism; D010101:Oxygen Consumption; D010806:Physical Education and Training / Q000379:methods*; D012039:Regional Blood Flow; D012865:Skiing / Q000502:physiology*; D034941:Upper Extremity / Q000502:physiology; D055815:Young Adult