Low resting heart rate and REDs

As a REDs and eating disorder specialist, I often see people bragging about their low resting heart rate as if it’s a badge of honor. Longevity experts and fitness influencers are often touting their low resting heart rate as if it’s the ultimate marker of health and athleticism.

In dance, bradycardia is often worn as a badge of fitness and conditioning but just as in other athletes, the full picture is more nuanced and sometimes a lower heart rate can be one of the first and most severe warning signs of something more dangerous, like Relative Energy Deficiency in Sport (REDs) or an eating disorder, not high performance.

Unfortunately, the dance and medical communities often don’t consider this nuance. I cannot tell you the number of times I’ve had a patient with severe anorexia nervosa, for instance, whose heart rate dropped after rapidly losing a large percentage of their body weight, be told their heart rate is low only because they are “in shape” by a medical professional.

What is a low resting heart rate? 

A low resting heart rate is known by the medical term, “bradycardia”. If bradycardia is solely due to an athletic training effect, then there are typically no medical concerns. 

Conversely, if bradycardia is due to malnutrition, it can be potentially life-threatening and predispose an individual to severe medical complications like cardiac arrhythmias, fainting episodes, and even sudden cardiac death.

Inadequate calories can do a number on virtually every organ system in the body, and one adaptation is to try to slow down some of the body’s functions, like the heart, as a survival mechanism. It’s almost like the body is trying to hibernate to preserve itself, so it slows the heart down in an attempt to slow you down until you can be better fueled.

Understanding your own heart rate

For dancers, bradycardia may come from training adaptation, REDs, or a combination of both. 

Even highly trained dancers typically sit at ≥50 bpm at baseline so understanding your baseline is key as context matters in helping to understand whether a low resting heart rate is healthy. 

A drop in baseline resting heart rate, especially with fatigue, injury, missed cycles, or low libido, can be an early indicator of REDs

Consider how your baseline resting heart rate compares to your current resting heart rate.

Things to keep in mind 

If your medical provider, teacher, or classmate praises your low resting heart rate, keep in mind that often they do not have proper education on other potential causes of bradycardia, like bradycardia due to improper nutrition.

If heart rate drops substantially in the context of an eating disorder or REDs, sometimes there may be an indication for hospitalization for closer cardiac monitoring.

For instance, the Society for Adolescent Health & Medicine considers a heart rate less than 50 during the day and less than 45 at night as being “unstable” and needing closer medical monitoring, possibly in an inpatient setting.

What to do if you’re concerned your low resting heart rate may not be so healthy

Seek a medical evaluation from a REDs savvy physician. Often further testing, like by getting an EKG and labs, are warranted.

One way to test if there’s a malnutrition component to your low heart rate is to work on improving your fueling, ideally by working with a Registered Dietitian knowledgable with REDs. 

In these cases, your resting heart rate should come up as you renourish, likely to above 45-50 beats per minute. This is NOT a sign of lost fitness, but rather a sign that your body is feeling better nourished. 

Written by Katherine Hill MD and Athleat MD