During exercise, heart rate can rise adequately from a resting rate of 60 - 80 beats per minute to a maximum rate of 200 for a young adult.
Explanation:
Regular exercise causes a reduction in Resting Heart Rate (RHR) because the heart muscle is always stronger and it is capable of pumping out more blood per heartbeat.
The body needs very little or less heartbeat to pump the same amount of blood.
The intensity of excercise exceeds 60% of person's maximum heart rate the increase in cardiac output is solely attributable to increase in heart rate.