title: Control of speed during the double poling technique performed by elite cross-country skiers.
abstract: OBJECTIVE
  Double poling (DP) as a main technique in cross-country skiing has developed substantially over the last 15 yr. The purpose of the present study was to analyze the question, "How do modern elite skiers control DP speed?"
  
  
  METHODS
  Twelve male elite cross-country skiers roller skied using DP at 9, 15, 21, and 27 km.h(-1) and maximum velocity (V(max)). Cycle characteristics, pole and plantar forces, and elbow, hip, and knee joint angles were analyzed.
  
  
  RESULTS
  Both poling frequency and cycle length increased up to 27 km.h (-1)(P < 0.05), with a further increase in poling frequency at V(max) (P < 0.05). Peak pole force, rate of force development, and rearfoot plantar force increased with submaximal velocities (V(sm)), whereas poling time and time-to-peak pole force gradually shortened (P < 0.05). Changes in elbow joint kinematics during the poling phase were characterized by a decreased angle minimum and an increased flexion and extension ranges of motion as well as angular velocities across V(sm) (P < 0.05), with no further changes at V(max). Hip and knee joint kinematics adapted across V(sm) by 1) decreasing angles at pole plant and angle minima during the poling phase, 2) increasing the ranges of motion and angular velocities during the flexion phases occurring around pole plant, and 3) increasing extension ranges of motion and angular velocities during the recovery phase (all P values <0.05), with no further changes at V(max).
  
  
  CONCLUSIONS
  Elite skiers control DP speed by increasing both poling frequency and cycle length; the latter is achieved by increased pole force despite reduced poling time. Adaptation to higher speeds was assisted by an increased range of motion, smaller angle minima, and higher angular velocities in the elbow, the hip, and the knee joints.
authors.affiliation: Department of Sport Science and Kinesiology, Christian Doppler Laboratory-Biomechanics in Skiing, University of Salzburg, Rifer Schlossallee 49, Hallein, Salzburg, Austria. stefan.lindinger@sbg.ac.at
authors.forename: Stefan Josef
authors.initials: SJ
authors.lastname: Lindinger
authors.forename: Thomas
authors.initials: T
authors.lastname: Stöggl
authors.forename: Erich
authors.initials: E
authors.lastname: Müller
authors.forename: Hans-Christer
authors.initials: HC
authors.lastname: Holmberg
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001696:Biomechanical Phenomena; D005080:Exercise Test; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D053580:Muscle Strength / Q000502:physiology*; D011187:Posture / Q000502:physiology; D012865:Skiing / Q000502:physiology*