New Study Reveals How Exercise Can Reverse Early Heart Disease — Better Than a Popular Weight-Loss Drug

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A Disease That Starts Long Before Symptoms Appear

Heart disease usually develops silently for years. Fatty deposits, called plaque, slowly build up inside the arteries. This process, known as atherosclerosis (hardening and narrowing of the arteries), eventually raises the risk of heart attacks and strokes.

For decades, doctors have focused mainly on cholesterol and medication to manage this risk. New research now points to another, less familiar factor: the immune cells made in our bone marrow.

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A Hidden Process Inside the Bone Marrow

Bone marrow constantly produces new blood cells. Over time, some of these cells can pick up random genetic mutations that give them a growth advantage over their neighbors.

This process is called clonal hematopoiesis, or CH — the uncontrolled expansion of one mutated cell line. It becomes more common as people age. According to the U.S. National Institutes of Health (NIH), this buildup of genetic changes in blood cells drives inflammation, and that inflammation can fuel atherosclerosis.

The mutated cells do not stay in the bone marrow. Some travel into the artery walls, where they promote chronic inflammation and accelerate plaque growth.

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What a Major New Study Found

A large international research team, led by cardiovascular researcher Cameron McAlpine at the Icahn School of Medicine at Mount Sinai, examined this connection in more than 90,000 people, using data from the UK Biobank and the U.S. All of Us Research Program. Physical activity was tracked with wearable devices rather than self-reported, making the results more reliable.

The findings, published in the journal Nature, showed that people with more moderate-to-vigorous physical activity had a lower rate of clonal hematopoiesis. This connection held true even after adjusting for body weight, suggesting exercise affects the mutant cells directly rather than only through weight control.

Poor, fragmented sleep showed the opposite effect. It was linked to a higher prevalence of these harmful blood cell mutations.

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Testing the Mechanism in Mice

To understand why this happens, the researchers turned to mice carrying the same mutations found in humans. Over twelve weeks, mice were kept sedentary, allowed to exercise, or subjected to disrupted sleep.

In the sedentary and sleep-disrupted mice, the mutant blood cell clones expanded steadily. In the exercising mice, that expansion nearly stopped.

The researchers also found a biological explanation. Exercise activated a specific group of neurons in the brainstem that release the hormone noradrenaline. This hormone signals to immune cells called macrophages inside the artery wall, reducing the inflammation these mutant cells would otherwise cause. Poor sleep, by contrast, boosted a different inflammatory pathway and worsened plaque buildup.

Notably, not every mutation responded the same way — cells carrying a mutation called Dnmt3a were not affected by either sleep or exercise, in both the mouse experiments and the human data.

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Exercise vs. a Popular Weight-Loss Drug

A second study, published in Nature Metabolism, adds further weight to the exercise argument. Researchers followed 130 adults with obesity for 52 weeks after a structured weight-loss program. Participants were randomly assigned to one of four groups: exercise, the GLP-1 medication liraglutide (from the same drug class as newer weight-loss injections), a combination of both, or neither.

Using ultrasound to measure carotid intima-media thickness (a marker of artery wall thickening), the researchers found that exercise, alone or combined with the drug, meaningfully reduced arterial thickening and inflammatory markers. According to lead researcher Signe Torekov, only participants who exercised achieved a clinically relevant reduction in artery thickness, corresponding to roughly a 25 percent lower estimated cardiovascular risk. Liraglutide on its own showed no measurable improvement in artery health, even though it helped maintain weight loss.

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What This Means in Practice

The takeaway from both studies is refreshingly simple: movement and sleep are not just "healthy habits" in a general sense. They appear to work on a specific biological process that drives heart disease.

Health guidelines generally recommend at least 150 minutes per week of moderate-to-vigorous activity — for example, brisk walking, cycling, swimming, or jogging for about 30 minutes on five days a week. Adding resistance training two to four times a week further supports long-term cardiovascular and muscular health.

Good sleep habits matter just as much. Keeping a consistent sleep schedule, limiting screen exposure before bed, and creating a cool, dark, quiet bedroom all support the biological processes described in the studies.

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Outlook

These findings do not mean medication has no role in cardiovascular care. But they do challenge the assumption that pharmaceutical treatment is always the most powerful option. In this research, the artery wall responded more strongly to physical activity than to a widely prescribed drug.

As clonal hematopoiesis research develops, scientists hope to identify which patients would benefit most from lifestyle intervention versus targeted drug therapy. For now, the evidence suggests that one of the most effective tools against heart disease costs nothing and is already available to almost everyone: regular movement and consistent, quality sleep.

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Sources

1. NIH Research Matters (National Institutes of Health): https://www.nih.gov/news-events/nih-research-matters/sleep-exercise-may-reduce-mutation-driven-inflammation
2. Nature — "Mutation-dependent responses to sleep and exercise in clonal haematopoiesis": https://www.nature.com/articles/s41586-026-10634-0
3. Nature Metabolism — "Effects of exercise and liraglutide on vascular health and inflammation during weight loss maintenance": https://www.nature.com/articles/s42255-026-01554-4
4. Healio — "Exercise, but not liraglutide, linked to decreased atherosclerosis development": https://www.healio.com/news/endocrinology/20250924/exercise-linked-to-decreased-atherosclerosis-development-but-not-liraglutide

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