title: Joint-specific power production during submaximal and maximal cycling.
abstract: Separate authors have reported that knee extension dominates power production during submaximal cycling (SUB(cyc)) and hip extension is the dominant action during maximal cycling (MAX(cyc)). Changes in joint-specific powers across broad ranges of net cycling powers (P(net)) within one group of cyclists have not been reported.
  
  
  OBJECTIVE
  Our purpose was to determine the extent to which ankle, knee, and hip joint actions produced power across a range of P(net) . We hypothesized that relative knee extension power would decrease and relative knee flexion and hip extension powers would increase as P(net) increased.
  
  
  METHODS
  Eleven cyclists performed SUB(cyc) (250, 400, 550, 700, and 850 W) and MAX(cyc) trials at 90 rpm. Joint-specific powers were calculated and averaged over complete pedal revolutions and over extension and flexion phases. Portions of the cycle spent in extension (duty cycle) were determined for the whole leg and ankle, knee, and hip joints. Relationships of relative joint-specific powers with P(net) were assessed with linear regression analyses.
  
  
  RESULTS
  Absolute ankle, knee, and hip joint-specific powers increased as P(net) increased. Relative knee extension power decreased (r(2) = 0.88, P = 0.01) and knee flexion power increased (r(2) = 0.98, P < 0.001) as P(net) increased. Relative hip extension power was constant across all P(net) . Whole-leg and ankle, knee, and hip joint duty cycle values were greater for MAX(cyc) than for SUB(cyc).
  
  
  CONCLUSIONS
  Our data demonstrate that 1) absolute ankle, knee, and hip joint-specific powers substantially increase as a function of increased P(net) , 2) hip extension was the dominant power-producing action during SUB(cyc) and MAX(cyc), 3) knee flexion power becomes relatively more important during high-intensity cycling, and 4) increased duty cycle values represent an important strategy to increase maximum power.
authors: Department of Exercise and Sport Science, University of Utah, Salt Lake City, UT 84112-0920, USA. Steve.Elmer@utah.edu
authors: Steven J
authors: SJ
authors: Elmer
authors: Paul R
authors: PR
authors: Barratt
authors: Thomas
authors: T
authors: Korff
authors: James C
authors: JC
authors: Martin
mesh_terms: D000328:Adult; D000843:Ankle Joint / Q000502:physiology*; D001642:Bicycling / Q000502:physiology*; D001696:Biomechanical Phenomena; D005080:Exercise Test; D006621:Hip Joint / Q000502:physiology*; D006801:Humans; D007719:Knee Joint / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000502:physiology; D055815:Young Adult