• You're all caught up!

Why Does Our Heart Rate Increase During Exercise?

author image Jim Sloan
Jim Sloan is a writer and editor in Reno, Nevada. He has been a journalist for more than 25 years and is the author of two books, "Staying Fit After Fifty," and "Nevada: True Tales from the Neon Wilderness."
Why Does Our Heart Rate Increase During Exercise?
Exercising at a steady pace for a prolonged period will cause your heart rate to increase. Photo Credit Mike Watson Images/moodboard/Getty Images

Your heart rate increases when you begin to exercise, then plateaus off and remains elevated for a prolonged period as long as you maintain the same pace. If you increase your effort, it will go even higher until you reach your maximal capacity. The quick responsiveness of your heart to exercise is due to the demand for oxygen in your muscles.

Speedy Delivery

Why Does Our Heart Rate Increase During Exercise?
Your heart beats faster and harder when exercising to send oxygen to your cells. Photo Credit Warren Goldswain/iStock/Getty Images

In order to continually produce energy for contraction, your muscles need oxygen. Oxygen is carried on your red blood cells from your lungs and travels to your heart to be pumped to your working muscles. Inside the muscle cells, tiny organelles called mitochondria combine oxygen with glucose and fat to make ATP, the basic energy molecule. When you increase your muscle action, your heart beats faster and harder to send oxygen to your cells, ejecting a greater volume of blood with each stroke.

Beating the Heat

Why Does Our Heart Rate Increase During Exercise?
High temperatures can raise your heart rate above normal levels. Photo Credit Maridav/iStock/Getty Images

High environmental temperatures during exercise can increases your heart rate above normal levels because your heart has to send blood to your skin to cool you down while continuing to supply blood to your working muscles. These two demands force your heart to beat faster. The more you train in a hot environment, the more efficient you become at cooling your body while satisfying the energy demands of your muscles.

Cardiovascular Drift

Why Does Our Heart Rate Increase During Exercise?
Your heart rate may gradually increase during long duration exercise. Photo Credit Warren Goldswain/iStock/Getty Images

During long-duration exercise, your heart rate may gradually increase, even if you maintain a set pace. This "cardiovascular drift" occurs as you lose water through sweating and as your heart directs more blood to your skin in order to cool you down. Your heart rate will increase because blood is being diverted from your working muscles, and therefore, it has to pump more often to keep your muscles supplied with oxygen and energy. Cardiovascular drift occurs regardless of whether you are staying hydrated. But according to researchers at the University of Texas, your heart rate will increase even more if you are getting dehydrated. A study of cyclists showed that a rising body temperature will also contribute to an increased heart rate during prolonged exercise.

All Systems Go

Why Does Our Heart Rate Increase During Exercise?
There are other things that can influence heart rate. Photo Credit kzenon/iStock/Getty Images

All your body's systems depend on oxygen, and your heart must continue to feed all your tissues while you exercise. According to the book "Essentials of Exercise Physiology," many other things affect heart rate during exercise, including your emotional state, how much food you've eaten prior to exercise, your body position and whether the exercise is continuous or characterized by periodic bursts. With regular training, your heart becomes stronger and pumps a greater volume of blood with less effort, lowering your heart rate at rest and during exercise. Your muscle cells grow more mitochondria and become more efficient at extracting and using oxygen, decreasing demand during exercise.

LiveStrong Calorie Tracker
Lose Weight. Feel Great! Change your life with MyPlate by LIVESTRONG.COM
  • Gain 2 pounds per week
  • Gain 1.5 pounds per week
  • Gain 1 pound per week
  • Gain 0.5 pound per week
  • Maintain my current weight
  • Lose 0.5 pound per week
  • Lose 1 pound per week
  • Lose 1.5 pounds per week
  • Lose 2 pounds per week
  • Female
  • Male
ft. in.



Demand Media