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Exercising with reserve: exercise regulation by perceived exertion in relation to duration of exercise and knowledge of endpoint
  1. J Swart,
  2. R P Lamberts,
  3. M I Lambert,
  4. E V Lambert,
  5. R W Woolrich,
  6. S Johnston,
  7. T D Noakes
  1. UCT/MRC Research Unit for Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Sports Science Institute of South Africa, Newlands, South Africa
  1. Correspondence to Dr J Swart, UCT/MRC Research Unit for Exercise Science and Sports Medicine, Sports Science Institute of South Africa, PO Box 115, Newlands 7725, South Africa; jeroen.swart{at}


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.

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  • Funding Funding for this research was provided by the Medical Research Council of South Africa, the University of Cape Town Harry Crossley and Nellie Atkinson Staff Research Funds, Discovery Health and the National Research Foundation of South Africa through the THRIP initiative.

  • Competing interests None.

  • Ethics approval The Research and Ethics Committee of the Faculty of Health Sciences of the University of Cape Town Medical School approved the study.

  • Patient consent Obtained.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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