title: Energy cost and pole forces during Nordic walking under different surface conditions.
abstract: BACKGROUND
  The purpose of the study was to identify the effect of three different surfaces on energy consumption and the forces acting on the walking poles during ground contact in Nordic walking (NW).
  
  
  METHODS
  Thirteen female NW instructors (age = 26 +/- 4 yr, weight = 58.5 +/- 4.2 kg, height = 168.1 +/- 4.6 cm) volunteered in the study. The subjects walked a distance of 1200 m at a controlled, constant speed of 2.2 m x s(-1) on each of a concrete surface (C), an artificial athletics track (A), and a naturally grown soccer lawn (G). They used NW poles with inbuilt strain gauge force transducers to measure ground reaction forces acting along the long axes of the poles. Oxygen uptake, capillary blood lactate (La), HR, and RPE were measured before and after the tests.
  
  
  RESULTS
  Impact forces, maximum forces, force rates during ground contact identified from the registered force time histories, displayed significant differences related to the surface conditions. However, force time integrals did not show surface-related differences. Relative oxygen consumption showed significant differences between NW on C and on G whereas no surface-related differences could be identified between the surface conditions for the parameters La, HR, and RPE.
  
  
  CONCLUSIONS
  Our data indicate that the impulse that is generated by the poles on the subjects is identical between the varying surfaces. Because there are differences for the oxygen uptake between C and G, the main regulator for the propulsion must be the musculature of the lower extremities. The work of the upper extremities seems to be a luxury effort for Nordic walkers with a proper technique.
authors.affiliation: Institute of Motor Control and Movement Technique, German Sport University Cologne, Cologne, Germany. t.schiffer@dshs-koeln.de
authors.forename: Thorsten
authors.initials: T
authors.lastname: Schiffer
authors.forename: Axel
authors.initials: A
authors.lastname: Knicker
authors.forename: Regine
authors.initials: R
authors.lastname: Dannöhl
authors.forename: Heiko K
authors.initials: HK
authors.lastname: Strüder
mesh_terms: D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D010101:Oxygen Consumption / Q000502:physiology; D013499:Surface Properties; D014159:Transducers; D016138:Walking / Q000502:physiology*
chemical_list: D019344:Lactic Acid