How could researchers confirm that fatigue is not an issue during the heart rate measurement experiment?

Measuring heart rate at a controlled room temperature before and after an experiment can help researchers confirm that fatigue is not influencing the heart rate measurements. By ensuring that the temperature remains constant, researchers can create an environment where external factors are minimized.

Fatigue can lead to variations in heart rate, and by taking measurements under consistent thermal conditions, researchers can isolate heart rate responses that are more likely related to the experimental variables rather than external stressors. If the heart rate maintains consistency across measurements taken before and after the experiment under the same conditions, it suggests that any variations are not due to fatigue but rather represent a reliable metric of the variable being studied.

On the other hand, taking measurements only after several hours may introduce fatigue, especially if participants are engaged in strenuous activities before measuring. Increasing the duration of measurement sessions can further confound results, as longer sessions may lead to increased fatigue over time. Using a single measurement throughout does not provide a comparative baseline, leaving open the possibility that fatigue may still influence the outcomes without prior data for comparison.