Which of the following is NOT used to measure exercise intensity?

Body temperature is not typically used to measure exercise intensity in the same way that other options are. When assessing exercise intensity, metrics such as heart rate provide direct physiological indicators of how hard the body is working. Heart rate increases in response to physical exertion, allowing individuals to gauge their intensity levels. The rating of perceived exertion scale gives individuals a subjective measure of how intense their exercise feels, which correlates to physiological responses. Pace, often expressed in terms of speed or distance covered over time, also serves as an effective measure of intensity, particularly in endurance activities.

In contrast, body temperature can fluctuate based on various factors and is not a direct measure of the intensity of exercise. While body temperature may rise during physical activity, specifically observing it to determine how intense a workout is could be less accurate and reliable compared to the established metrics mentioned. Thus, it does not fit within the context of measuring exercise intensity alongside heart rate, perceived exertion, or pace.