title: The effect of variable practice on wheelchair propulsive efficiency and propulsive timing.
abstract: OBJECTIVE
  The net mechanical efficiency of wheelchair propulsion is very low, approximately 13%. It is necessary to look for effective practice methods to obtain greater output with less energy expenditure during wheelchair propulsions. Literature indicates that variable practice (VP) is more effective than constant practice (CP) in motor-skill learning. However, it is unknown if VP is more effective than CP in improving wheelchair propulsive efficiency. The purpose of the study was to determine how propulsive efficiency and propulsive timing were affected by variable practice and constant practice.
  
  
  METHODS
  This was an observational and experimental study.
  
  
  METHODS
  The experiment was conducted in a well-controlled university research laboratory.
  
  
  METHODS
  A total of 33 able-bodied subjects participated in this study.
  
  
  METHODS
  Participants were randomly placed into one of the three training groups, two constant practice groups and one variable practice group. One constant group practiced wheelchair propulsion on a roller system with a single speed, 30% of the maximum speed, while the other constant group practiced using 55% of the maximum speed. The variable group practiced with both speeds. Three dependent variables, propulsive efficiency, timing, and intercycle variability of the timing, were measured.
  
  
  RESULTS
  All groups improved the three dependent variables significantly after the training, and in general the VP group had greater improvement than the others in improving the propulsive efficiency.
  
  
  CONCLUSIONS
  This study is the first to demonstrate the advantage of the VP over the CP in improving the propulsive efficiency.
  
  
  CONCLUSIONS
  This finding has great implication for paraplegics because they require greater workloads for upper-extremity activities.
authors.affiliation: Department of Health and Kinesiology, College of Education and Human Development, The University of Texas at San Antonio, San Antonio, TX, USA. wanxiang.yao@utsa.edu
authors.forename: W X
authors.initials: WX
authors.lastname: Yao
authors.forename: A
authors.initials: A
authors.lastname: Cordova
authors.forename: W
authors.initials: W
authors.lastname: De Sola
authors.forename: C
authors.initials: C
authors.lastname: Hart
authors.forename: A F
authors.initials: AF
authors.lastname: Yan
mesh_terms: D000054:Acceleration; D000328:Adult; D001696:Biomechanical Phenomena; D006233:Persons with Disabilities / Q000534:rehabilitation*; D005246:Feedback; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D009048:Motor Skills / Q000502:physiology*; D013647:Task Performance and Analysis; D014163:Transfer, Psychology / Q000502:physiology*; D014910:Wheelchairs / Q000706:statistics & numerical data*; D055815:Young Adult