Scalar-linear increases in perceived exertion are dissociated from residual physiological responses during sprint-distance triathlon

Abstract

ObjectiveThis study examined how residual fatigue affects the relationship between ratings of perceived exertion (RPE), physiological responses, and pacing during triathlon performance. MethodsEight male triathletes completed a sprint-distance triathlon (750m swim, 20kmcycle and 5km run) and isolated 5km run on separate days. RPE, core temperature (Tcore), heart rate and blood lactate concentration [BLa−] were recorded during both, in addition to performance time and speed. ResultsTriathlon run time (1248±121s) was significantly slower than the isolated run (1167±90s) (p<0.01). Significant differences were observed at the start of the two conditions for all physiological measures (Heart rate 162±4 vs 154±5 beatsmin−1; Tcore 38.3±0.8 vs 36.7±0.6C; [BLa−] 9.1±2.8 vs 2.1±0.4mmolL−1, for triathlon and isolated run, respectively, p<0.05). No significant differences were observed for initial RPE (p=0.083), rate of RPE increase (p=0.412), or final RPE (p=0.329) between run trials. ConclusionsThe maintenance of a scalar-linear increase in RPE by the brain remains the primary mechanism for pace regulation during both single and multi-modal endurance performance, with physiological responses being only indirectly related to this process. The apparent absence of any RPE ‘resetting’ between disciplines suggests that during shorter distance multi-sport performances (60–90 min) a cognitive pacing strategy for the entire event is employed. However, as subtle alterations in RPE development between disciplines were observed the existence of discipline-specific RPE ‘templates’ should not be discounted.