The purpose of heart rate monitoring during exercise is to gauge the intensity of a workout and ensure it falls within a safe and effective range. By tracking heart rate, individuals can optimize their training by maintaining a target heart rate zone that maximizes fat burning and cardiovascular benefits. Heart rate monitoring also helps in preventing overtraining and injury. Devices that track heart rates provide real-time feedback, enabling users to adjust their workouts accordingly. This data is crucial for designing personalized fitness plans and achieving specific health and fitness goals.