title: Metabolic Responses and Pacing Strategies during Successive Sprint Skiing Time Trials.
abstract: This study aimed to examine the metabolic responses and pacing strategies during the performance of successive sprint time trials (STTs) in cross-country skiing.
  
  
  
  Ten well-trained male cross-country skiers performed four self-paced 1300-m STTs on a treadmill, each separated by 45 min of recovery. The simulated sprint time trial (STT) course was divided into three flat (1°) sections (S1, S3, and S5) involving the double poling subtechnique interspersed with two uphill (7°) sections (S2 and S4) involving the diagonal stride subtechnique. Treadmill velocity and V˙O2 were monitored continuously, and gross efficiency was used to estimate the anaerobic energy supply.
  
  
  
  The individual trial-to-trial variability in STTs performance time was 1.3%, where variations in O2 deficit and V˙O2 explained 69% (P < 0.05) and 11% (P > 0.05) of the variation in performance. The first and the last STTs were equally fast (228 ± 10 s) and ~1.3% faster than the second and the third STTs (P < 0.05). These two fastest STTs were associated with a 14% greater O2 deficit (P < 0.05), whereas the average V˙O2 was similar during all four STTs (86% ± 3% of V˙O2max). Positive pacing was used throughout all STTs, with significantly less time spent on the first than second course half. In addition, metabolic rates were substantially higher (~30%) for uphill than for flat skiing, indicating that pacing was regulated to the terrain.
  
  
  
  The fastest STTs were characterized primarily by a greater anaerobic energy production, which also explained 69% of the individual variation in performance. Moreover, the skiers used positive pacing and a variable exercise intensity according to the course profile, yielding an irregular distribution of anaerobic energy production.
authors.affiliation: 1Department of Health Sciences, Swedish Winter Sports Research Centre, Mid Sweden University, Östersund, SWEDEN; 2Swedish Olympic Committee, Stockholm, SWEDEN; and 3Department of Sports Science and Clinical Biomechanics, SDU Muscle Research Cluster, University of Southern Denmark, Odense, DENMARK.
authors.forename: Erik
authors.initials: E
authors.lastname: Andersson
authors.forename: Hans-Christer
authors.initials: HC
authors.lastname: Holmberg
authors.forename: Niels
authors.initials: N
authors.lastname: Ørtenblad
authors.forename: Glenn
authors.initials: G
authors.lastname: Björklund
mesh_terms: D054874:Athletic Performance / Q000502:physiology*; D004734:Energy Metabolism; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D012865:Skiing / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult