Ask A Scientist

Why does our heart rate increase after we exercise?

Asked by: Matthew Slilaty
School: Vestal Hills Elementary School
Grade: 5
Teacher: Mrs. Selby
Hobbies/Interests: Collecting monster trucks
Career Interest: Engineering

Answer from Jennifer Wegmann

Lecturer, Binghamton University

Research area Eating disorders and body image Interests/hobbies: Exercising, reading, writing Family: Husband, Tom; two Sons - Nick (12) & TJ (10)

Before we get to the “heart” of the answer it is important to understand what your heart does. The heart, which is a muscle, pumps blood throughout the body.  You could actually think of your heart as two pumps. The right side pumps blood that is lacking oxygen to your lungs where it is then oxygenated. The left side pumps the oxygenated blood to the rest of the body. This amazing organ pumps more than a gallon of blood per minute and will beat more than 100,000 times a day. Circulating blood throughout the body is vital because blood delivers nutrients and oxygen to our cells and removes carbon dioxide that is eventually expelled when you exhale.

The reason your heart rate increases when exercising is because your muscle cells need more oxygen. It is the heart’s responsibility to circulate blood and oxygen, and when your body’s needs increase, then your heart has to work harder. The harder or more intensely you exercise the higher your heart rate. However, increasing your heart rate too much can be dangerous. We all have a maximum rate at which our heart can beat and you can approximate what yours is by subtracting your age from 220. For example, I am 36 years old; therefore my estimated maximum heart rate is 184 beats per minute. It is recommended that exercise be sustained at an intensity that will raise the heart rate between 60-90% of the maximum.

 Since the heart is a muscle it needs to be toned and strengthened like any other muscle in your body. Therefore, when you exercise and your heart rate goes up your heart is becoming stronger and more efficient. The benefit is that when you are not exercising your heart does not have to beat as many times to keep your blood circulating. In other words your heart rate actually decreases, which is a good thing because there is less stress on it. I know it may seem odd but by increasing your heart rate during exercise you in turn decrease you’re over all heart rate.

There are some who go overboard with exercise, a topic which filmmaker Darryl Roberts explores thoroughly in his documentary America the Beautiful. The film examines America’s obsession with physical perfection. In America the Beautiful, we learn secrets, confessions, and strikingly harsh realities as Roberts unearths the origins and deadly risks of our nation’s quest for physical perfection. Roberts will be on the Binghamton University campus for a screening of his movie at 7 p.m. Thursday, February 12 in the Osterhout Concert Theater located in the Anderson Center. After the movie, which is free and open to the public, Roberts will participate in a panel discussion with members of the campus community.  For more information contact me Jennifer Wegmann at


Last Updated: 3/1/17