State one rease why an individual's pulse rate increased during exercise

The heart must beat faster during exersise because by increasing the heart rate the body is able to increase cardiac output and deliver the necessary blood flow to the mucles

The circulatory system allows you to pump more blood and is responding to how much of the energy that you are using to exercise. Oxygen is all around your body in which you blood vessels actually start to pump out more blood having your pulse rate increasing.