title: Velocity-specific fatigue: quantifying fatigue during variable velocity cycling.
abstract: Previous investigators have quantified fatigue during short maximal cycling trials ( approximately 30 s) by calculating a fatigue index. Other investigators have reported a curvilinear power-pedaling rate relationship during short fatigue-free maximal cycling trials (<6 s). During maximal trials, pedaling rates may change with fatigue. Quantification of fatigue using fatigue index is therefore complicated by the power-pedaling rate relationship.
  
  
  OBJECTIVE
  The purpose of this study was to quantify fatigue while accounting for the effects of pedaling rate on power.
  
  
  METHODS
  Power and pedaling rate were recorded during Union Cycliste Internationale sanctioned 200-m time trials by eight male (height = 181.5 +/- 4.3 cm, mass = 87.0 +/- 8.0 kg) world-class sprint cyclists with SRM power meters and fixed-gear track bicycles. Data from the initial portion of maximal acceleration were used to establish maximal power-pedaling rate relationships. Fatigue was quantified three ways: 1) traditional fatigue index, 2) fatigue index modified to account for the power-pedaling rate relationship (net fatigue index), and 3) work deficit, the difference between actual work done and work that might have been accomplished without fatigue.
  
  
  RESULTS
  Fatigue index (55.4% +/- 6.4%) was significantly greater than net fatigue index (41.0% +/- 7.9%, P < 0.001), indicating that the power-pedaling rate relationship accounted for 14.3% +/- 7% of the traditional fatigue index value. Work deficit (23.3% +/- 6%) was significantly less than either measure of fatigue (P < 0.001).
  
  
  CONCLUSIONS
  Net fatigue index and work deficit account for the power-pedaling rate relation and therefore more precisely quantify fatigue during variable velocity cycling. These measures can be used to compare fatigue during different fatigue protocols, including world-class sprint cycling competition. Precise quantification of fatigue during elite cycling competition may improve evaluation of training status, gear ratio selection, and fatigue resistance.
authors.affiliation: Department of Physiology, English Institute of Sport, Manchester, United Kingdom. scott.gardner@eis2win.co.uk
authors.forename: A Scott
authors.initials: AS
authors.lastname: Gardner
authors.forename: David T
authors.initials: DT
authors.lastname: Martin
authors.forename: David G
authors.initials: DG
authors.lastname: Jenkins
authors.forename: Iain
authors.initials: I
authors.lastname: Dyer
authors.forename: Jan
authors.initials: J
authors.lastname: Van Eiden
authors.forename: Martin
authors.initials: M
authors.lastname: Barras
authors.forename: James C
authors.initials: JC
authors.lastname: Martin
mesh_terms: D000054:Acceleration; D000465:Algorithms; D001642:Bicycling / Q000502:physiology*; D005080:Exercise Test; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D005082:Physical Exertion / Q000502:physiology