How is intensity commonly measured during training?

Intensity during training is commonly measured as a percentage of maximum heart rate because heart rate is a reliable indicator of how hard the body is working during physical activity. By determining an individual's maximum heart rate, which can be estimated using the formula 220 minus the person's age, trainers can calculate various intensity levels for workouts.

For example, training at 50-60% of maximum heart rate is typically seen as a light intensity, while 70-85% indicates moderate to vigorous intensity. This percentage-based approach allows individuals to tailor their training sessions to meet specific fitness goals, whether that's improving cardiovascular endurance, losing weight, or increasing performance in athletics.

While heart rate variability, self-assessed fatigue levels, and duration of the training session can provide insight into training effects and overall exertion, they do not provide the direct measure of intensity that heart rate percentages do. This specific method aligns well with physiological principles behind exercise and provides a consistent and quantifiable way to gauge effort during physical activity.