HEAT STRESS IS MODIFIED BY TEMPERATURE AND TYPE OF WORK AND REFLECTED IN RATINGS OF PERCEIVED EXERTION
Green, J. M., Yang, Z., Laurent, C. M., Davis, J.-K., Kerr, K., Pritchett, R. C., & Bishop, P. A. (2007). Session RPE following interval and constant-resistance cycling in hot and cool environments. Medicine and Science in Sports and Exercise, 39, 2051-2057.
This study examined effects of heat gain, heart rate adjustment to temperature regulation, and lactate consequent to interval and constant-load cycling on session rating of perceived exertion (S-RPE). Male volunteers (N = 10) completed a cycle ergometer VO2peak test and then four cycling bouts, including constant load (~45% VO2peak) and interval (8 x 1-minute at ~90% VO2peak, 1 minute between work intervals), in hot (~32.5°C) and cool (~21.0°C) environments. Trials included a standardized 10-minute warm-up and cool-down. Total external work was equated for all trials, with blood lactate, heart rate, rectal temperature, and acute RPE being recorded at 10, 13, 17, 21, 25, and 36 minutes. S-RPE was recorded 20 minutes after each session.
Both forms of work resulted in significantly greater heat gain, heart rate, and RPE-O. Interval work had significantly elevated lactate values compared to the constant-load work in both cool and hot conditions. In the heat, S-RPE was significantly higher than in the cool condition for constant and interval work. S-RPE was significantly higher for interval work than constant work in the heat.
Implication. Heat gain, heart rate, and lactate levels are affected by environmental temperature and type of exercise while total work is held constant. Added heat strain is reflected in elevated S-RPE for both constant and interval work. RPE and S-RPE are similar.
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