When Should Runners Worry About Surging Heart Rates?

If you’re a regular runner — or going as far as training for a marathon or half-marathon — you’ve probably had those worrisome moments when your heart rate is racing faster than normal, even during an otherwise “easy run.”

Runners or individuals who are very active in any sport tend to have lower heart rates at rest. And they have the ability to maintain an unwavering pace through moderate to intense activities. But is it a red flag when the higher heart rate kicks in unexpectedly even for the most experienced runners?

Eli Friedman, M.D., medical director of sports cardiology at Miami Cardiac & Vascular Institute.

Most of those moments -— especially among runners who are healthy overall — are usually nothing to worry about, explains Eli Friedman, M.D., medical director of sports cardiology at Miami Cardiac & Vascular Institute. However, there are some red flags that should prompt a visit with your doctor for a faster-than-normal heart rate. Those include symptoms that may accompany the racing heart rate such as shortness of breath, chest discomfort, irregular heartbeats, nausea, lightheadedness, or passing out.

Most significantly, a runner shouldn’t compare herself or himself to a fellow runner.

“How the heart responds is very genetically driven,” Dr. Friedman says. “How fast or slow one person’s heart beats on a run can be completely different from somebody else’s.”

It’s also easy to obsess over a heart rate with the wide availability of smartwatch and smartphone applications that can detect heart rates and irregular heartbeats. “Wrist-based heart rate monitors are not 100 percent reliable, and the more you’re moving, the less reliable the data,” explains Dr. Friedman. “So, there’s a chance a high reading may not be accurate.”

In addition to genetics, there are other factors that may influence heart rates in runners. On average, women’s hearts are smaller, and have to beat faster to supply the body with oxygen and other nutrients — although training can reduce the need for the heart to beat faster. Additionally, your height and amount of muscle mass also play a role, as can breathing patterns.

There is another factor that regular runners should consider. The range of symptoms that an athlete can experience, especially over the age of 35, can be somewhat similar to the general cardiac population — including chest pain or discomfort, skipping heartbeat, shortness of breath, and unusual fatigue — but more difficult to discern at first, said Dr. Friedman.

“How an athlete will experience these problems can sometimes be different,” said Dr. Friedman. “They might notice somewhat precipitously that they’re not hitting their times on their miles as much, and that it’s taking more energy than they would expect to complete their usual training regimen. So, how athletes experience these issues is very different compared to the general population.”

Baptist Health South Florida is a sponsor and the official medical provider for the 2022 Life Time Miami Marathon & Half on Feb. 6, providing assistance at the various first-aid and medical stations along the full route. Many of Baptist Health’s healthcare professionals take part in the event, either by helping distressed runners or by running part or all of the 26.2-mile course themselves.