title: Effect of low recumbent angle on cycling performance, fatigue, and V˙O(2) kinetics.
abstract: OBJECTIVE
  This study aimed to examine the effect of the degree of inclination from upright to supine postures on cycling performance, fatigue, and oxygen uptake (V˙O(2)) kinetics.
  
  
  METHODS
  In experiment 1, 10 subjects performed graded and fatigue (exhaustive constant-load heavy exercise with 10 s all-out efforts interspersed every minute) tests at four cycling postures: upright, 30° recumbent (R), 15° R, and supine. In experiment 2, nine different subjects performed two bouts of constant-load heavy exercise in the same four cycling postures. Bout 1 was brought to failure, and bout 2 was limited to 6 min, so that the breath-by-breath V˙O(2) data from the first 6 min of each bout were averaged and curve fit.
  
  
  RESULTS
  The time sustained during the graded test was significantly shorter in the supine compared with the other three postures and also shorter in the 15° R compared with the upright. The rate of fatigue was higher in the supine compared with the other three postures, and the normalized EMG activities of three leg muscles at end exercise were larger in the supine (and in some cases 15° R) compared with upright posture. The time sustained (min) during high-intensity constant-load cycling was significantly longer during upright (12.8 ± 5.3) and 30° R (14.2 ± 6.1) compared with 15° R (8.5 ± 1.7) and supine (6.8 ± 2.0) postures, but the amplitudes of the slow component of the V˙O(2) response (L·min) were larger during 15° R (0.57 ± 0.10) and supine (0.61 ± 0.15) compared with 30° R (0.39 ± 0.12) and also larger in the supine than upright (0.43 ± 0.13) postures. Inert gas rebreathing analysis revealed similar cardiac output responses at 60 s into the exercise among postures.
  
  
  CONCLUSIONS
  Lowering the recumbent angle to 15° resulted in shorter performance, larger fatigue, and altered V˙O(2) kinetics.
authors.affiliation: Department of Physiology, Trinity College Dublin, Dublin, Ireland. megana@tcd.ie
authors.forename: Mikel
authors.initials: M
authors.lastname: Egaña
authors.forename: David
authors.initials: D
authors.lastname: Columb
authors.forename: Steven
authors.initials: S
authors.lastname: O'Donnell
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology*; D001642:Bicycling / Q000502:physiology*; D001696:Biomechanical Phenomena; D004576:Electromyography; D005080:Exercise Test / Q000295:instrumentation / Q000379:methods; D006801:Humans; D007494:Ireland; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D011187:Posture / Q000502:physiology*; D055815:Young Adult