title: Effect of push frequency on the economy of wheelchair racers.
abstract: OBJECTIVE
  The aim of the study was to examine the effect of varying push frequency on pushing economy (oxygen uptake at a given speed).
  
  
  METHODS
  Eight male wheelchair racers completed a series of exercise bouts on a wheelchair ergometer (Bromking Turbo Trainer, Bromakin, UK) at 6.58 m x s(-1). Initially, subjects self-selected their freely chosen push frequency (FCF); this was followed by 4 random trials pushing at 60, 80, 120, and 140% of this FCF. Steady state VO2 was determined using Douglas bags, and heart rate was recorded by telemetry. After each condition, a small capillary blood sample was obtained and analyzed for blood lactate concentration (BLa) and a rating of perceived exertion (RPE) was recorded.
  
  
  RESULTS
  At 6.58 m x s(-1) oxygen uptake, RPE, and gross mechanical efficiency were nonlinearly related to push frequency. Analysis of variance showed a significant effect (P < 0.05) of cycle frequency on VO2. VO2 was 11% higher at the 140% FCF compared with the 100% FCF condition. Changes in push frequency had little effect on HR although BLa increased linearly and was higher at the 140% FCF condition compared with 60% FCF (P < 0.05). A two-dimensional sagittal plane video analysis showed large interindividual differences in propulsion style. Both cycle time and the propulsion phase (%) decreased as the push frequency increased. The start angle and end angle of hand contact were similar for conditions, whereas the range of trunk motion decreased with push frequency (P < 0.05).
  
  
  CONCLUSIONS
  The results of this study showed that the push frequency had an effect on pushing economy, and that the athletes' FCF was the most economical.
authors.affiliation: Department of Exercise and Sport Science, Manchester Metropolitan University, Alsager, United Kingdom. v.l.goosey@mmu.ac.uk
authors.forename: V L
authors.initials: VL
authors.lastname: Goosey
authors.forename: I G
authors.initials: IG
authors.lastname: Campbell
authors.forename: N E
authors.initials: NE
authors.lastname: Fowler
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001696:Biomechanical Phenomena; D016552:Ergometry; D005080:Exercise Test; D006225:Hand / Q000502:physiology; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D019344:Lactic Acid / Q000097:blood; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010465:Perception; D005082:Physical Exertion / Q000502:physiology; D013177:Sports / Q000502:physiology*; D013686:Telemetry; D013909:Thorax / Q000502:physiology; D013997:Time Factors; D014743:Videotape Recording; D014910:Wheelchairs
chemical_list: D019344:Lactic Acid