Work Rate Adjustments During a High-intensity Interval Training on a Stationary Bike in a Hot and Temperate Environment

The goal of this repeated measures study is to evaluate acute work rate adjustments during high-intensity interval training (HIIT) in a hot and temperate environment in healthy and active adults when using target heart rate to prescribe the exercise intensity. The main questions it aims to answer are: * Will HIIT based on target heart rate in a hot environment result in increased cardiovascular (i.e., elevated recovery HR) and thermal strain compared to HIIT in a temperate environment? * Will work rate be lowered to a greater extent during HIIT in a hot environment compared to a temperate environment in order to maintain target heart rate? * Will maximal aerobic capacity (V̇O2max) decrease to a greater extent after HIIT in the heat compared to a temperate environment? Procedures: Participants will complete 5 trials on a cycle ergometer. Trial 1 (Control Visit): Participants (n = 7) will have their maximal heart rate and V̇O2max measured in a temperate environment (\~22 °C, 40% RH). Experimental Trials 2-5: The order of the trials will be counterbalanced and randomly assigned to participants. * 15TEMP: Participants will cycle at 70% of their maximum heart rate for 8 minutes as a warm-up, followed by one round of HIIT. The HIIT protocol consists of 4 minutes at 90% of maximum heart rate followed by 3 minutes at 70% of maximum heart rate, totaling 15 minutes, in a temperate environment (\~22 °C, 40% RH). After the HIIT session, a graded exercise test will measure V̇O2max. * 15HEAT: Similar to 15TEMP, but participants will perform the HIIT protocol in a hot environment (\~35 °C, 40% RH). * 43TEMP: Participants will cycle at 70% of their maximum heart rate for 8 minutes as a warm-up, followed by the HIIT protocol repeated four times (4 minutes at 90% of maximum heart rate and 3 minutes at 70% of maximum heart rate), totaling 43 minutes, in a temperate environment (\~22 °C, 40% RH). * 43HEAT: Similar to 43TEMP, but participants will perform the HIIT protocol in a ho