This aerobic range is generally between 60 and 85 percent of a person's maximum heart rate. If you are severely overweight or in poor shape, the aerobic range may be 50 to 65 percent of your maximum heart rate. Aerobic exercise uses large muscle groups for a continuous period of time. To handle this workload, the muscles need more oxygen. This requires the heart to beat faster.
Breathing gets heavier and faster to take in more oxygen for the muscles.
To estimate your aerobic heart rate range, subtract your age from 220. This gives your estimated maximum heart rate. Then multiply your maximum heart rate by 60 percent and by 85 percent. These numbers are the low and high numbers representing heartbeats per minute in your aerobic range. These numbers are an estimate of how hard your heart needs to work.