Regular exercise helps strengthen the heart muscles, which could contribute to a lower resting heart rate for athletes. But a low heart rate is sometimes a symptom of a heart condition.

Heart rate, or pulse, is measured in beats per minute (bpm).

Your resting heart rate provides insight into how hard your heart is pumping blood when you’re at rest. It’s usually measured when you’re sitting or lying down and in a calm state.

According to the American Heart Association (AHA), the average resting heart rate is between 60 and 100 bpm. But athletes often have a lower resting heart rate than others, with some as low as 40 bpm.

If you’re a very active person, a lower resting heart rate isn’t usually something to be concerned about, unless you experience feelings of dizziness, tiredness, or illness. In fact, it typically means you’re in good shape.

An athlete’s resting heart rate may be lower than that of the general population. For instance, an athlete may have a resting heart rate of 40 bpm, according to the AHA.

During exercise, your heart pumps more blood with each heartbeat, delivering more oxygen to your muscles. Just like other muscles in your body, repetitive exercise helps strengthen your heart muscle over time.

The heart becomes more efficient at pumping larger amounts of blood, which means that for athletes, it beats fewer times per minute to deliver the same amount of blood.

According to a 2018 review, all types of regular physical activity can help decrease your heart rate. But yoga and endurance training like running, cycling, and swimming were particularly beneficial for resting heart rates.

Resting heart rates vary for everyone, including athletes. Some factors that could influence it include:

  • age
  • fitness level
  • exercise types, intensity, and duration
  • air temperature (on hot or humid days, heart rate may increase)
  • emotion (stress, anxiety, and excitement can increase heart rate)
  • medication (beta-blockers can slow heart rate, while some thyroid medications can increase it)

How low is too low?

For most athletes, a slow resting heart rate is usually only considered too low when they have other symptoms.

A slow resting heart rate is a condition known as bradycardia. Symptoms of bradycardia may include:

These symptoms can sometimes indicate another medical issue that could require medical treatment.

If you experience any of these symptoms, especially if they occur frequently during exercise, contact a primary care physician. They can assess your symptoms and medical history and determine if you need to see a medical specialist, such as a cardiologist, for further evaluation.

Athletic heart syndrome (AHS) is a heart condition in which the left ventricle of the heart has thicker walls, increased cavity dimensions, and more mass. AHS may also be accompanied by an arrhythmia (irregular heart rhythm).

These changes are usually caused by frequent bouts of high intensity exercise over long periods of time.

Although AHS is usually harmless, it may show up as abnormal on an electrocardiogram (ECG). Usually, there’s no need to diagnose AHS because it doesn’t present any health problems.

However, the changes that occur in an athlete’s heart may sometimes be similar to those caused by other heart conditions, such as hypertrophic cardiomyopathy (HCM), myocarditis, and pulmonary hypertension.

In fact, there may be overlap between AHS and other heart conditions, so it’s important to speak with a healthcare professional if you experience:

  • frequent chest pain
  • irregular heart rates
  • fainting during exercise

Occasionally, athletes do collapse due to a heart problem. But that’s usually because of an underlying condition such as congenital heart disease, not AHS.

Some research suggests that athletes have a higher risk of developing bradycardia and incidence of electronic pacemaker implantation later in life.

However, research is still ongoing on the long-term effects of endurance exercise.

For most people, a normal resting heart rate is between 60 and 100 bpm.

Well-trained athletes may have a resting heart rate around 40 bpm, but everyone’s heart rate is different. There’s no “ideal” resting heart rate, but a rate may indicate that you have better cardiovascular fitness.

Here’s how to check your resting heart rate at home, which is best done first thing in the morning:

  1. Gently press the tips of your index and middle fingers over the lateral part of your wrist, just below the thumb side of your hand.
  2. Count the beats for a full minute.

Your maximum heart rate is considered the highest amount your heart can sustain during cardiovascular training.

There are several ways to estimate your maximum heart rate, but they all have some degree of error. The easiest way is to subtract your age from 220.

For instance, if you’re 35 years old, then your maximum heart rate would be 185 bpm.

Some people follow target-heart-rate training, which is based on intensity level compared to maximum heart rate. Moderate activity is usually around 50% to 70% of your maximum heart rate, while high intensity is 70% to 85%.

So, if you’re 35 years old and are aiming to exercise at a high intensity, then your target heart rate would be between 130 and 157 bpm. Using a heart rate monitor is a great way to keep track during exercise.

Going higher than your calculated maximum heart rate for long periods of time may be dangerous for your health. Always stop exercising if you feel lightheaded, dizzy, or ill.

People who exercise frequently may have a lower resting heart rate than other people.

This isn’t necessarily a bad thing. A low heart rate means your heart needs fewer beats to deliver the same amount of blood throughout your body.

That said, sometimes a slower heart rate is an indication of a heart condition that could require medical treatment.

Connect with a healthcare professional if you experience dizziness, chest pain, or fainting during exercise. They can assess your heart to confirm you can continue exercising.