The main indicator of the load is the pulse. The body will begin to burn fats only at a heart rate of 65-75% of the maximum value. The average occupation time is about an hour, because during such trainings it takes from 18-20 to 40 minutes to start the mechanism of fat burning. Another principle is used in interval training. In this case, the heart rate should reach 95% of the maximum value. Then the body will burn 90% carbohydrates, 1% protein and 10% fat.