Selected physiological and perceptual responses of males during prolonged exercise

Six males of similar body composition and aerobic physical fitness were tested to determine their perceptual responses to exercise and the relation of these perceptions to core temperature (Tᵣₑ) under three conditions of thermoregulatory stress. The experimental protocol consisted of 120 min of upright stationary cycling at 50% VO₂ max under conditions of neutral (24°C, 50% RH/hydration (NH), hot (35°C, 50% RH/hydration (HH), and hot (35°, 50% RH/hypohydration (HP). Perceptual responses were determined by Borg's 10-point category ratio scale ( 1980) and by a multi-dimensional symptom scale which contained six symptoms commonly thirst; associated with heat stress: irritability; headache; and weakness; fatigue; dizziness. Core temperature responses and perceptions were obtained throughout exercise in each condition. An analysis of variance was utilized to determine if significant differences existed between Tᵣₑ responses, symptom scale responses and RPE responses in each condition. Analysis of variance revealed statistically significant (P < 0.05) differences between Tᵣₑ responses in the three conditions. Statistically significant (P < 0. 05) differences were also found for the symptom scale responses of thirst and weakness. Regression analysis within each condition was utilized to evaluate the relationship of Tᵣₑ and RPE responses and of Tᵣₑ and the combined scores of weakness, fatigue and thirst. The regression analysis revealed an R² or . 997 for prediction of Tᵣₑ using RPE data in the HP trial; the R² for Tᵣₑ prediction from the symptom scale responses in HP was 0.992. The R² values for prediction of Tᵣₑ in the NH and HH conditions were .953 and .983, respectively. The R² obtained in the HH and NH conditions were lower than those R² obtained in the HP trials for both the RPE and symptom scale predictors. These data suggest that RPE is a meaningful predictor of Tᵣₑ increases i.e., given a particular RPE, the model gives a meaningful estimate of Tᵣₑ within the range of core temperatures that were observed.