How Heart Rate is Related to Fitness

Understand how your heart works to help you get the best workout.


By Maddy Bond


Our heart has a pretty big job to do. Its duty is to pump blood around our entire body, constantly. It sends blood to the tips of your toes, your stomach for digestion, and to your brain to function. Whether we’re exercising or not, your heart is always at work, pumping blood around the entire body to transport vital nutrients to every single cell.

For explanation’s sake, we’ll say the process starts in the heart, where blood is deoxygenated (has no oxygen attached to it). It is then sent to the lungs to receive oxygen, and returns to the heart to be pumped throughout the entire body, including your muscles.

Heart rate can be a key indicator of an individual's level of fitness. Have you ever exercised so hard that you felt as if your heart was going to beat out of your chest? This is potentially because you are at your maximum heart rate level. As the level of energy required to perform an activity, such as exercise, increases, so does your heart rate.

This is because the muscles being used during exercise require more oxygen and energy to perform than they do at rest. In order to deliver those nutrients as quickly as possible, the brain will send a signal to the heart to increase its rate. The blood will flow quicker, and oxygen will be delivered faster to the muscles that require it. A conditioned heart will usually have a lower heart rate due to cardiovascular fitness and efficiency.

During exercise, the working muscles get their fix of blood and oxygen, but it’s not like your body completely stops sending blood to all other areas. If that were the case, our bodies would pretty much shut down as soon as we started exercising! Instead, your nervous system sends signals to decrease blood flow to non-essential areas like the digestive system — hence why some people experience stomach issues when they eat a big meal before a workout. It also decreases blood flow to muscles that might not be doing a lot of work. For example, when running, how much work are your arms really doing? They may be pumping as you move, but you’re not using them as much as your legs. The blood flow to the arms decreases slightly, and blood flow to the legs increases, sending nutrients to fuel the harder work.

Heart rate is a reflection of fitness relative to an individual’s activity level, cardiovascular efficiency, and muscular efficiency. The more efficient an individual’s heart is (or, how well it sends nutrients to those hard working muscles), the more fit that person typically is. However, this can be conditioned to the individual and their specific activity. For example, the muscles of a runner and a swimmer are each conditioned for the specific movements of their sports, and are therefore more efficient at those motions. This means they don’t need as much energy to perform their trained activities. However, have them switch sports and their heart rate will be much higher, simply because their muscles are not as efficient at those movements, and will require more oxygen to perform.

Studies have shown that regular cardiovascular exercise (for example, running, swimming, jump rope etc.) may decrease your overall heart rate. So, if you want to test it out, start by measuring your heart rate immediately after a cardio session. Train regularly, two or three times a week at the same or slightly higher intensity.

After four to six weeks, repeat the exercise and intensity of the initial test day and immediately measure your heart rate following the session to compare.

A reduction in heart rate has shown to improve quality of life, reduce the risk of heart disease, and increase longevity. When your heart is conditioned and able to function at a lower rate, it does less work, which means less wear and tear over the course of your life. If your heart rate is high for your age, it’s going to be doing more work while you’re resting — therefore, more wear and tear. For obvious reasons, of all of our muscles, the heart is the one we need to last the longest. What we do with our body and what we put into our body can determine what happens to our heart.

Maddy has worked in the health and fitness industry for 5 years. She has a bachelors in Exercise Science and has recently received her Masters in Exercise Physiology. She has worked with a wide demographic of clients as a Personal Trainer and loves helping people reach their goals and continue to grow.  She is an outdoor enthusiast and dedicates her workouts to rock climbing, hiking and whatever new experiences may come her way.

Main Photo Credit: Crdjan/; Second Photo Credit: BallBall14/; Third Photo Credit: Andrey_Popov/