title: Effects of body position on slide boarding performance by cross-country skiers.
abstract: OBJECTIVE
  In this study, we examined the effects of body position (from deep to high position) in slide boarding by well-trained cross-country skiers. The main hypothesis was that a deeper, more "crouched" position would lead to reduced air resistance and enhanced power production during explosive extension of the lower limbs, and thereby to an increased performance, even though the upper extremity may not be used for poling in this deep position.
  
  
  METHODS
  Measurements (air resistance in a wind tunnel, power output, kinematics, gas exchange, and blood lactate levels) were performed during a 30-s maximal test and a 3-min maximal test performing (imitation) ski-skating movements on a sliding board at three different body positions (high, moderate, and deep).
  
  
  RESULTS
  Our findings indicate that a deep position enhances power production by 24% and reduces air resistance by 30% for the 30-s maximal test. Power production did not increase in the 3-min test, but lactate levels after exercise were increased in the deep position. Calculated efficiency was not affected by body position.
  
  
  CONCLUSIONS
  The current results indicate that for a short duration, the deeper sit provides sufficient advantages that it may prove useful to apply such a position in sprint ski-skating, even though the use of the upper extremities in poling will be strongly hampered.
authors.affiliation: Human Movement Science Programme, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Stig
authors.initials: S
authors.lastname: Leirdal
authors.forename: Lars
authors.initials: L
authors.lastname: Saetran
authors.forename: Karin
authors.initials: K
authors.lastname: Roeleveld
authors.forename: Beatrix
authors.initials: B
authors.lastname: Vereijken
authors.forename: Steinar
authors.initials: S
authors.lastname: Bråten
authors.forename: Sveinung
authors.initials: S
authors.lastname: Løset
authors.forename: Andreas
authors.initials: A
authors.lastname: Holtermann
authors.forename: Gertjan
authors.initials: G
authors.lastname: Ettema
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010806:Physical Education and Training / Q000379:methods; D010807:Physical Endurance / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D011659:Pulmonary Gas Exchange; D012865:Skiing / Q000502:physiology*