Rating of perceived exertion and heart rate as indicators of exercise intensity in different environmental temperatures

This study examined the validity of rating of perceived exertion (RPE) and heart rate (HR) obtained during incremental exercise (INC) as indicators of intensity during constant load exercise (CL). Nine cyclists (VO2max = 53.3 +/- 8.9 ml.kg-1.min-1) performed INC to determine intensity at the onset of blood lactate accumulation (OBLA). Three CL work bouts at OBLA were performed in an environmental chamber with temperatures (30 degrees C, 22 degrees C, 14 degrees C) randomly assigned. RPE and HR were determined every 5 min. Data during CL from initial 5 min (5 MIN), second 5 min (10 MIN), midpoint (MID), and exhaustion (END) were used in treatment by time ANOVA to examine differences between temperature conditions, with repeated measures ANOVA testing for differences between INC and CL. Tukey HSD post-hoc tests identified mean differences, with significance set at P < or = 0.01. No significant differences across temperature conditions for RPE or HR were found. RPE obtained at OBLA during INC (13.7 +/- 0.9) was significantly different from 5 MIN, 10 MIN, MID, and END during CL in all temperatures. HR obtained at OBLA during INC (165.4 +/- 12.3 bpm) was significantly higher than 5 MIN for all temperatures (30 degrees C = 153.0 +/- 9.9; 22 degrees C = 151.0 +/- 11.8; 14 degrees C = 150.2 +/- 13.8), but was not significantly different from INC for 10 MIN, MID, or END measures. The data indicate HR is a more valid marker of exercise intensity than RPE.