a heart rate monitor during workouts lets you track key information besides just how fast your heart is beating. “When you exercise, you’re using energy,” explains Travers. “And when you’re measure your heart rate, you’re able to figure out what energy source you’re using.”
The higher your heart rate gets, the more calories you’re burning. “But,” , “the higher your heart rate is, you’re burning more carbohydrates than fat for energy because your body can’t burn fat fast enough.” By using a heart rate monitor during a workout, you can adjust your energy output to match your heart rate to the best level to burn fat.