Which two factors are critical for determining exercise intensity?

Heart rate and perceived exertion are critical for determining exercise intensity because they provide direct and subjective measures of how hard the body is working during physical activity.

Heart rate is a quantifiable biomarker that reflects cardiovascular effort; it increases with the intensity of the exercise. Monitoring heart rate allows individuals to gauge whether they are training at a low, moderate, or vigorous intensity. For instance, specific heart rate zones can indicate different training goals, such as fat burning or cardiovascular conditioning.

Perceived exertion, often measured through subjective scales like the Borg Rating of Perceived Exertion (RPE), allows individuals to assess how they feel during an activity based on their experience of exertion. This subjective measure is especially useful because it can account for individual differences, such as fitness levels, fatigue, and mental state, that may not be reflected in heart rate alone.

Combining these two factors gives a comprehensive understanding of exercise intensity, allowing for appropriate adjustments to training programs to meet fitness goals.