Work Rate Adjustments During a High-intensity Interval Training on a Stationary Bike in a Hot and Temperate Environment
Condition: High-Intensity Interval Training; Heat
Study type: Interventional

Summary: 
      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 hot
           environment (~35 °C, 40% RH).
    


Intervention name(s): 15 minutes of high-intensity interval training; 43 minutes of high-intensity interval training; Hot environment; Temperate environment
Intervention type(s): Behavioral; Behavioral; Other; Other
Intervention description(s): Participants completed an 8 min warm-up and 1 round of high-intensity interval training; Participants completed an 8 min warm-up and 5 rounds of high-intensity interval training; Participants exercised in a hot environment, ~ 35 °C, ~40% relative humidity.; Participants exercised in a temperate environment, ~ 22 °C, ~40% relative humidity.
Allocation: Randomized
Intervention model: Crossover Assignment
Intervention model description: Participants completed all trials and were compared to themselves.
Masking: None (Open Label)
Primary purpose: Other