title: Exercising with reserve: exercise regulation by perceived exertion in relation to duration of exercise and knowledge of endpoint.
abstract: OBJECTIVE
  The purpose of this study was to examine ratings of perceived exertion (RPE) and performance during repetitive maximal effort 40 km time trials as well as after an intervention that aimed to decrease certainty about the remaining distance of the exercise bout. In addition, we examined the RPE during exercise bouts of markedly different duration.
  
  
  METHODS
  Part 1: 12 well-trained, competitive-level cyclists completed five 40 km time trials. During the final time trial all feedback was withheld until the final kilometre. In addition, to cause confusion about the remaining distance, they were asked to report their RPE at random intervals from 18 km to 38 km. Part 2: 6 well-trained, recreation-level cyclists randomly completed a 5 km, 10 km, 40 km and 100 km time trial.
  
  
  RESULTS
  Part 1: Mean RPE increased during the first four trials and decreased during the final trial. The rate of RPE progression increased in linearity during the first four trials and became more conservative in the final trial. These changes were directly related to performance. Part 2: Mean RPE for longer duration trials (40 km, 100 km) were lower during the first half of trial duration but matched those of shorter trials in the final 20%.
  
  
  CONCLUSIONS
  Increased familiarity of the exercise bout and certainty about its endpoint are associated with a more aggressive RPE strategy that produces a superior exercise performance. Certainty about the endpoint and the duration of exercise affect both the RPE strategy and performance.
authors.affiliation: UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Sports Science Institute of South Africa, PO Box 115, Newlands 7725, South Africa. jeroen.swart@uct.ac.za
authors.forename: J
authors.initials: J
authors.lastname: Swart
authors.forename: R P
authors.initials: RP
authors.lastname: Lamberts
authors.forename: M I
authors.initials: MI
authors.lastname: Lambert
authors.forename: E V
authors.initials: EV
authors.lastname: Lambert
authors.forename: R W
authors.initials: RW
authors.lastname: Woolrich
authors.forename: S
authors.initials: S
authors.lastname: Johnston
authors.forename: T D
authors.initials: TD
authors.lastname: Noakes
mesh_terms: D000328:Adult; D054874:Athletic Performance / Q000502:physiology; D001642:Bicycling / Q000502:physiology; D004734:Energy Metabolism / Q000502:physiology; D015444:Exercise / Q000502:physiology* / Q000523:psychology*; D005080:Exercise Test; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D010465:Perception; D010807:Physical Endurance / Q000502:physiology; D005082:Physical Exertion / Q000502:physiology*