title: Energy cost and efficiency of ski mountaineering. A laboratory study.
abstract: OBJECTIVE
  The purpose of this study is to estimate the energy cost of ski mountaineering at different speeds under laboratory conditions.
  
  
  METHODS
  By using roller skis on a motorized treadmill we have estimated the energy cost and biomechanics parameters of ski mountaineering as a function of climbing speed at the gradient of 21%.
  
  
  RESULTS
  The metabolic energy spent for unit mass and distance, C, shows a broad minimum of about 10.6±0.2 J kg-1m-1 at roughly 3.5 km h-1. In addition we find a size-dependent effect: tall subjects spend less metabolic energy for unit mass and distance than small subjects at the same speed.
  
  
  CONCLUSIONS
  The value of C measured in laboratory agrees with that obtained in the field at the preferred speed. This shows that skiers self select a speed that minimizes their metabolic cost. The dependence of C on the subject's size is explained by a simple model of the skier's dynamics. In addition we have calculated the ratio between mechanical work and metabolic energy, which may give some hints on the efficiency as a function of the speed. It turns out that efficiency increases with the speed up to a maximum located at around 4.5 km/h.
authors.affiliation: Department of Physics, University of TrentoPovo, Trento, Italy. paolo.tosi@unitn.it
authors.forename: P
authors.initials: P
authors.lastname: Tosi
authors.forename: A
authors.initials: A
authors.lastname: Leonardi
authors.forename: L
authors.initials: L
authors.lastname: Zerbini
authors.forename: A
authors.initials: A
authors.lastname: Rosponi
authors.forename: F
authors.initials: F
authors.lastname: Schena
mesh_terms: D000328:Adult; D001827:Body Height / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D008954:Models, Biological; D009051:Mountaineering / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology; D012865:Skiing / Q000502:physiology*
chemical_list: D019344:Lactic Acid