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The influence of peripheral afferent signals on the rating of perceived exertion and time to exhaustion during exercise at different intensities


  • Flávio Pires is grateful to CAPES (Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior) for his scholarships (PDEE BEX 1900/08-0) and FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) for the financial support to this study (Process 2006/60641-6). Timothy Noakes and Mike Lambert are supported by the Discovery Health, the Medical Research Council, and the University of Cape Town.

  • The authors acknowledge the presence of a different manuscript (Pires et al., 2011, British Journal of Sports Medicine, In Press, published online, April 4, 2011; DOI: 10.1136/bjsm.2010.079087) which utilized the same data to respond to a different objective.

Address correspondence to: Flávio O. Pires, University of São Paulo, School of Physical Education and Sport, 65, Prof. Mello Moraes Avenue – Butantã, Zip code: 05508-030, São Paulo, SP, Brazil. E-mail:


This study determined which peripheral variables would better predict the rating of perceived exertion (RPE) and time to exhaustion (TE) during exercise at different intensities. Ten men performed exercises at first lactate threshold (LT1), second lactate threshold (LT2), 50% of the distance from LT1 to LT2 (TT50%), and 25% of the distance from LT2 to maximal power output (TW25%). Lactate, catecholamines, potassium, pH, glucose, V̇O2, VE, HR, respiratory rate (RR) and RPE were measured and plotted against the exercise duration for the slope calculation. Glucose, dopamine, and noradrenaline predicted RPE in TT50% (88%), LT2 (64%), and TW25% (77%), but no variable predicted RPE in LT1. RPE (55%), RPE+HR (86%), and RPE+RR (92% and 55%) predicted TE in LT1, TT50%, LT2, and TW25%, respectively. At intensities from TT50% to TW25%, variables associated with brain activity seem to explain most of the RPE slope, and RPE (+HR and+RR) seems to predict the TE.