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PURPOSE: This study examined effects of heat gain, circulatory adjustment to temperature regulation (HR), and La consequent to interval (INT) and constant-load (CON) cycling on session RPE (S-RPE). METHODS: Male volunteers (N = 10) completed a cycle ergometer VO2peak test and then, in a randomized, counterbalanced order, four cycling bouts, including constant load (approximately 45% VO2peak) (CON) and interval (8 x 1 min at about 90% VO2peak, 1 min between intervals) (INT), in hot (approximately 32.5 WBGT) (HOT) and cool (approximately 21.0 WBGT) (COOL) environments. Trials included a standardized warm-up and cool-down (10 min each: 0 W, 60 rpm). Total external work was equated among all trials, with blood lactate (La), heart rate (HR), rectal temperature (Tre), and acute RPE recorded at 10, 13, 17, 21, 25, and 36 min. S-RPE was recorded 20 min after each session. RESULTS: HOT (CON and INT) resulted in significantly (P < 0.05) greater heat gain (Tre), HR, and RPE-O, whereas INT had significantly elevated La versus CON (HOT and COOL). HOT yielded significantly higher S-RPE versus COOL for CON (HOT = 5.6 +/- 2.1, COOL = 4.3 +/- 1.3) and INT (HOT = 7.0 +/- 1.9, COOL = 5.1 +/- 2.0). S-RPE was significantly higher for INT/HOT than CON/HOT. CONCLUSIONS: Heat gain and cardiac strain (Tre, HR) and La) were manipulated with environment and exercise type while holding total work constant. The added strain of HOT was reflected in elevated S-RPE for both CON and INT. S-RPE linkage with La was limited to HOT trials, indicating only a loose association. These data indicate that under the conditions of this study, S-RPE is similar to acute RPE in that no single mediator seems universally dominant.
GREEN et al. (Thu,) studied this question.