Which of the following factors is important when monitoring exercise intensity?

Monitoring exercise intensity is crucial for ensuring that individuals are performing at a level that is safe and effective for their fitness goals. Heart rate is one of the most important physiological indicators of exercise intensity.

As exercise intensity increases, so does heart rate, reflecting the body's demand for oxygen and the need to circulate blood more rapidly to deliver nutrients to muscles. By tracking heart rate, one can assess whether they are working within their target heart rate zone, which is essential for both maximizing fitness gains and minimizing the risk of overtraining or injury.

Evaluating body temperature, breathing rate, and muscle fatigue can provide some insight into physical exertion, but heart rate remains a direct and quantifiable measure of how hard the heart is working, making it the most reliable parameter for monitoring exercise intensity.