Doctors now say weightlifting is safe for people carrying a dangerous heart gene

A registry study led by Johns Hopkins Medicine has found that strength training carries no added risk of dangerous heart rhythm problems for people who live with or carry genes for arrhythmogenic cardiomyopathy, a heritable condition that can trigger sudden cardiac arrest in a person’s 20s to 40s. The findings, published Sept. 10 in JACC: Clinical Electrophysiology, drew on 355 participants tracked from childhood into middle age. Investigators sorted those participants by exercise pattern and measured how often each group experienced a sustained ventricular arrhythmia.

About one in every 1,000 to 5,000 people worldwide is estimated to carry arrhythmogenic cardiomyopathy, caused by mutations in genes that weaken the heart muscle’s ability to contract and pump blood. Physicians have long steered these patients away from high-intensity aerobic exercise such as competitive cycling or distance running. Until this study, they had little data on whether lifting weights, climbing or practicing martial arts carried a similar danger.

355 patients tracked from childhood into middle age

Researchers working through the Johns Hopkins Arrhythmogenic Right Ventricular Cardiomyopathy Registry interviewed participants by phone about their physical activity levels going back to age 10. They sorted people into four groups: endurance athletes, who logged at least four hours a week of vigorous aerobic activity such as cycling, swimming or running; strength athletes, who logged at least two hours a week of weightlifting, climbing or martial arts; dual athletes, who did both; and a sedentary group that met neither threshold. Participants joined the registry at a median age of 34 and were followed until a median age of 44, and 70% already carried an arrhythmogenic cardiomyopathy diagnosis when they enrolled.

Ventricular arrhythmia in the study meant a rapid, sustained heartbeat lasting more than 30 seconds at 100 beats per minute or faster, ventricular fibrillation or flutter, sudden cardiac arrest or death, or the use of an implantable cardiac device. Just over half of all participants, 55%, experienced one of those events during the study, and roughly half of those cases occurred around the time someone first enrolled — often the same event that led to their diagnosis in the first place.

The study’s ten-author team was led by Katia Chiampas, with Hugh Calkins among the senior collaborators. The full author list also included Steven Muller, Evans Osuji, Alan Jacobsen, Lisa Yanek, Richard Cararick, Alessio Gasperetti, Crystal Tichnell and Brittney Murray, spanning cardiology, biostatistics and the registry’s coordinating staff. That breadth reflects how the Johns Hopkins ARVC Registry has grown large enough to answer a question — strength versus endurance risk, specifically — that a single hospital’s caseload of this rare condition could not have settled on its own a decade ago.

Strength training carried no added risk, endurance training did

Dual and endurance athletes together were 58% more likely to experience a ventricular arrhythmia than the combined strength and sedentary groups, according to the study. There was no meaningful difference in risk between dual athletes and pure endurance athletes. Strength athletes, by contrast, showed no significant increase in ventricular arrhythmia risk compared with the sedentary group — the finding that opens the door to weightlifting as an option rather than a gamble for this population.

Sustained, heart-pumping exercise like sprinting or cycling places prolonged demand on the right ventricle, the chamber most affected by arrhythmogenic cardiomyopathy, and that repeated strain is what clinicians have worried could damage already-vulnerable heart tissue over years. Strength training, done in shorter bursts, does not appear to load the heart the same way, which is consistent with why the two exercise types produced such different outcomes in the registry. Notably, the risk difference showed up only between endurance-type activity and everything else — dual athletes who mixed both forms of exercise fared no worse than pure endurance athletes, suggesting the aerobic component, not the presence of any strength work, is what drove the higher rate.

Lili Barouch: from blanket bans to personalized decisions

Lili Barouch, director of the sports cardiology program at the Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease and the study’s senior author, whose findings appear in the JACC: Clinical Electrophysiology journal record, framed the result as a shift away from one-size-fits-all restrictions. “There have been a lot of questions about the safety of strength training for people living with or at risk for arrhythmogenic cardiomyopathy,” Barouch said. “This study opens the door to help researchers further assess this — and supports continued shifts with moving away from blanket recommendations for exercise to support personalized decision-making between physicians and patients.”

That framing matters because cardiologists managing arrhythmogenic cardiomyopathy have historically erred toward caution across the board, sometimes discouraging any vigorous activity rather than distinguishing between exercise types. A registry large enough to separate strength from endurance outcomes gives physicians a specific, evidence-based conversation to have instead of a categorical no.

What counted as strength training in the study

Strength athletes in the registry averaged more than 2.75 hours of weekly weightlifting, climbing or martial arts before enrolling, a figure that fell to just under an hour a week by the time researchers followed up years later. Endurance and dual athletes, by comparison, averaged about six hours of weekly aerobic exercise before enrollment, dropping to roughly two hours a week later on. Men and women were split almost evenly across the 355 participants, and strength athletes made up the smallest of the four groups at just 7%, behind dual athletes (55%), the sedentary group (26%) and endurance athletes (12%).

Cindy James, research director at the Johns Hopkins ARVC Program and the Johns Hopkins Center for Inherited Heart Diseases, said the results feed directly into how doctors and patients talk about exercise going forward. Physical activity matters enormously to people living with or at risk for arrhythmic cardiomyopathy, James said, which is exactly why data like this carries weight beyond the registry itself. “This is one of many reasons why research in this area is critical to inform shared medical decisions to support a person’s physical health and their overall wellbeing,” James said.

This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.

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