Can Too Much Cardio Actually Be a Bad Thing?

We often hear about the heart-healthy benefits of going on a long jog or participating in a HIIT class, but could too much aerobic activity actually be a bad thing?

It’s complicated, at least according to Dr. Lutz Petersdorf, MD, vice president, Bayer Head of Global Medical Category Allergy & Cough/Cold, Pain & Cardio. “There have been concerns regarding the safety of long-distance running, especially after some runners died of heart attacks, including the famous Jim Foxx, author of The Complete Book of Running in 1984,” he says. “Many scientists, physicians, and athletes began to worry that long-term, strenuous exercise might actually be bad for the heart.”

But after countless studies and decades of research, the general consensus is that a healthy amount of cardio — specific to the individual and his or her fitness levels and needs — is generally a-okay.

We chatted with Petersdorf to discuss the evidence that supports this claim, including when someone may actually be at risk of participating in activities that stress the heart.

Health History Plays an Important Role

To preface this deep dive into the potentially harmful effects of cardio, Petersdorf reiterates that consulting a healthcare provider (HCP) is a critical first step before “starting or making drastic changes” to a workout routine.

“The HCP will run the necessary diagnostic work-up according to the athlete’s medical background, including family history of cardiovascular disease, hypertension, diabetes, and personal health, e.g. obesity or metabolic syndrome,” says Petersdrof. “This medical check-up might discover hidden cardiac risk factors, including heart electrical abnormalities which could trigger a sudden cardiac death event if left undiagnosed.”

That being said, an adult male in good physical health likely has nothing to worry about. Petersdorf cites a landmark study from 2017 as evidence.

Out of 50 men who had completed a total of 3,510 marathon runs, heart scans “could not find a relationship between how much they had run overall and how much plaque they had in their arteries.”

Instead, the heart health of 10 subjects with “worrisomely large” deposits of plaque could be attributed to external factors like a “a history of heavy smoking and high cholesterol, especially in the men who had begun running later in life.” “The good news for long-distance runners was that the findings of this study suggest that years of hard running had not harmed the men’s hearts,” says Petersdorf. “But the exercise also had not inoculated those with a history of unwise lifestyle choices, especially smoking, against developing heart disease.” “This last finding can be summarized with words from Dr. William O. Roberts, a professor of family and community medicine at the University of Minnesota, who led the study: ‘You can’t just outrun your past’” he adds. Other studies have reported “greater plaque stability in exercisers,” which ultimately indicates that higher levels of physical activity may be favorable to lower the risk of cardiovascular events, including those with higher incidence of plaque.

“However, extreme situations, as seen from the impact of ultramarathon runs, suggest there [may] be an upper limit for the cardiovascular benefits of exercise,” Petersdorf explains. “There is also data that shows that individuals who maintain very high levels of physical activity (around three times recommended levels) have higher odds of developing coronary artery calcification (CAC), particularly in white males.”

“In general, this mixed evidence only highlights that it is a very individual situation and, as stated, the need to consult your HCP to ultimately find the right balance,” Petersdorf concludes.

Short vs. Long-Distance Running Benefits and Risks

Despite the limited findings that excess exercise may have a negative impact on heart health, it should not deter most men from engaging in aerobic activity. Petersdorf is quick to point out that the American Heart Association currently recommends “at least 150 minutes per week of moderate-intensity aerobic activity or 75 minutes per week of vigorous aerobic activity, or a combination of both, preferably spread throughout the week.”

“Running is a very popular form of engaging in aerobic activity. It has been shown to lower blood pressure, lower heart rate, improve metabolism, delay diabetes, promote weight loss, and prolong life,” he adds. In fact, a 2014 study of 55,000 people, conducted by the Journal of the American College of Cardiology, showed a positive correlation between heart health and running among the group.

In contrast, another area of research shows that ultramarathoners (those who race more than 26.2 miles) may have the opposite impact on their hearts in the form of “damage, rhythm, and other concerns.”

“An upper limit for the cardiovascular benefits of exercise is further supported by a recent study showing that individuals who completed at least 25 marathons over a period of 25 years have higher than expected levels of coronary artery calcification (CAC) and calcified coronary plaque volume when compared with sedentary individuals,” says Petersdorf.

But still, the “current controversy only highlights the need to have a medical check-up before starting any new exercise routine, especially if the adult is planning to engage in any medium to long-distance running activity,” Petersdorf adds.

The Risks of Obesity and Aerobic Activity

When it comes to those who are overweight, slow and steady always wins the race.

“The most important advice to any overweight or obese individual is to have a medical clearance before embarking in any new or intensified exercise routine,” advises Petersdorf. “Overweight and obesity are additional cardiac risk factors. An HCP needs to run the medical check-up and determine if any additional cardiac risk factors are present or if there is a need for specific extra diagnostic tests, including but not limited to an ECG, a stress ECG, an echocardiogram, and others if needed.”

The general recommendation is to always start easy and work your way up to individual goals and not overexert yourself.

“If you’re physically unable to complete 30 minutes of exercise this week, do what you can and build toward 30 minutes daily over time,” suggests Petersdorf. “You’ll still experience the benefits of fitness if you break those 30 minutes into two or three groups of 10 to 15 minutes throughout the course of the day. When you begin, don’t allow yourself to get hung up on the clock. Instead, focus on picking an activity that you enjoy and that can fit into your schedule at least three to five days a week.”

Final Thoughts

Whether you’re hoping to become a little more active, complete your first marathon, or train for IronMan competition number five, it’s important to consult a trusted medical professional before embarking on any fitness journey. Do not let a few “freak incidents” deter you from challenging the limits of your body, but do accept that there is zero harm in proactively running a few tests to give you the all-clear and peace of mind. The expression may be overused, but you’d rather be “safe than sorry”, especially when it comes to your health.