Monitoring heart rate during exercise is significant for several reasons. It helps individuals gauge exercise intensity and ensure they are training within their target heart rate zone for optimal benefits. Tracking heart rate can prevent overtraining or undertraining, making workouts more efficient and effective. It also aids in maximizing caloric expenditure, supports cardiovascular health, and helps assess overall fitness levels over time. Using devices like heart rate monitors can provide real-time feedback, allowing for better adjustments during workouts to meet specific fitness goals.