Noakes and colleagues [1] have proposed that the rising RPE produced during exhaustive exercise acts as a protective mechanism during exercise, overriding the conscious desire to increase the exercise intensity if such an increase could threaten homeostasis, either at that moment or sometime in the future. Accordingly, athletes maintain a reserve capacity, presumably to prevent any catastrophic failure of homeostasis. Methods: We examined the rate of RPE increase during repetitive maximal effort time trials as well as after an intervention which aimed to decrease certainty about the remaining distance of the exercise bout. In addition, we examined the rate of RPE increase during bouts of markedly different duration. Part 1: 12 well-trained, competitive level cyclists completed five 40km 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 18km to 38km. Part 2: 6 well-trained, recreation level cyclists randomly completed a 5km, 10km, 40km and 100km time trial. Results: Part 1: Mean ratings of perceived exertion increased during the first 4 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 ratings of perceived exertion for longer duration trials (40km, 100km) were lower during the first half of trial duration but matched those of shorter trials in the final 20%. Conclusions: We showed that the rate of increase in perceived exertion during exercise is not always repeatable, but changes in relation to certainty about the endpoint of exercise as well as the set exercise duration. When subjects were initially unfamiliar with the exercise bout, they chose a perceived exertion strategy that maintained a larger metabolic reserve which was then accessed near the end of the bout. With increased familiarity with the required exercise task, the RPE strategy became more aggressive, linear and with less metabolic and cardiorespiratory reserve. This was associated with increased performance. Similarly, during exercise bouts of longer duration, subjects started exercise bouts with lower RPE scores and maintained these lower RPE values until the final 20-30% of the exercise bout, after which they increased the RPE to values similar to those recorded during the shorter exercise trials. Subjects therefore maintained a greater metabolic and cardiorespiratory reserve during longer trials.
© Copyright 2009 14th annual Congress of the European College of Sport Science, Oslo/Norway, June 24-27, 2009, Book of Abstracts. Veröffentlicht von The Norwegian School of Sport Sciences. Alle Rechte vorbehalten.