What is a practical indicator of adequate heat acclimation in a trained athlete?

• A. A higher resting heart rate during heat exposure.
• B. Greater dehydration risk during exercise.
• C. Lower heart rate for a given workload.
• D. Delayed sweating onset.

Answer: (C)

A practical indicator of adequate heat acclimation in a trained athlete is a lower heart rate for a given workload during heat exposure. As acclimation occurs, plasma volume expands and stroke volume increases, so the heart can sustain the same exercise intensity with fewer beats. This reduces cardiovascular strain and helps manage heat more efficiently, often alongside more efficient sweating and heat dissipation. In practice, testing a standardized submaximal effort in the heat and observing a lower heart rate after acclimation indicates improved adaptation. Higher resting heart rate in the heat, greater dehydration risk, or delayed sweating onset would suggest less adaptation rather than adequate acclimation.