title: The valid measurement of running economy in runners.
abstract: Oxygen cost (OC) is commonly used to assess an athlete's running economy, although the validity of this measure is often overlooked.
  
  
  OBJECTIVE
  This study evaluated the validity of OC as a measure of running economy by comparison with the underlying energy cost (EC). In addition, the most appropriate method of removing the influence of body mass was determined to elucidate a measure of running economy that enables valid interindividual comparisons.
  
  
  METHODS
  One hundred and seventy-two highly trained endurance runners (males, n = 101; females, n = 71) performed a discontinuous submaximal running assessment, consisting of approximately seven 3-min stages (1 km·h increments), to determine the absolute OC (L·km) and EC (kcal·km) for the four speeds below lactate turn point.
  
  
  RESULTS
  Comparisons between models revealed linear ratio scaling to be a more suitable method than power function scaling for removing the influence of body mass for both EC (males, R = 0.589 vs 0.588; females, R = 0.498 vs 0.482) and OC (males, R = 0.657 vs 0.652; females, R = 0.532 vs 0.531). There were stepwise increases in EC and RER with increments in running speed (both, P < 0.001). However, no differences were observed for OC across the four monitored speeds (P = 0.54).
  
  
  CONCLUSIONS
  Although EC increased with running speed, OC was insensitive to changes in running speed and, therefore, does not appear to provide a valid index of the underlying EC of running, likely due to the inability of OC to account for variations in substrate use. Therefore, EC should be used as the primary measure of running economy, and for runners, an appropriate scaling with body mass is recommended.
authors.affiliation: 1English Institute of Sport, Loughborough University, Loughborough, UNITED KINGDOM; and 2School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UNITED KINGDOM.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Shaw
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Ingham
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Folland
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D015992:Body Mass Index; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008297:Male; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology*; D012189:Retrospective Studies; D012420:Running / Q000502:physiology*; D055815:Young Adult