Physical Activity
In order to keep adequate oxygenation of the muscles when working out, the heart has to beat faster. As the intensity of exercise increases, the respiratory rate increases to bring more oxygen into the system and the heart beats faster in order to transport that oxygen. MayoClinic.com recommends that people not exceed a moderate intensity workout that keeps the heart rate in between 75 and 80 percent of its maximum rate, which contributes to good heart health.