Your heart rate is increased during physical activity to increase cardiac output and deliver the blood flow needed to the muscles to carry out those activities. Your heart itself is a muscle, and also gets a workout during exercise. The job of the heart is to get more blood to the body's muscles when they work hard. Hope this helped.
Your heart rate gets faster when you exercise because the heart is known as a muscle, and when you work out, your heart also gets a workout from it, too. The blood flow of the heart will increase at least between four or five times from where you were while you were resting. The heart has a job, just like all of the other organs in your body. The heart's main focus is to send more blood to the body's muscles when your muscles are working hard. For example, lifting a barbell with 40 pounds on each side or by lifting yourself up off the ground as you are doing a pull up.
