Swimming versus running: Which is better for your heart health? New study offers answers

3 min readNew DelhiUpdated: Jun 22, 2026 02:44 PM IST

The results showed that both running and swimming improved heart health compared to no exercise at all. But the swimming group showed bigger changes in both the structure and function of the heart. (AI-generated image/Canva AI)

Running and swimming are both widely recognised as effective forms of endurance exercise for improving heart health. However, a new study published in the Scientific Reports journal suggests that swimming may produce stronger heart adaptations than running under experimental conditions.

The study is making waves by suggesting swimming might actually be better for your heart than running. But before runners ditch their shoes and dive into the pool, it’s worth slowing down and looking at what the researchers actually found.

Methodology

The researcher used rats, and they split the animals into three groups. One did not exercise at all, another followed a running routine, and the third did a swimming routine. Both exercise groups trained for the same amount of time, so the researchers could fairly compare the two activities.

The results showed that both running and swimming improved heart health compared to no exercise at all. But the swimming group showed bigger changes in both the structure and function of the heart.

Key findings of the study

The hearts of the swimming rats developed larger heart muscle cells, something scientists call physiological cardiac hypertrophy. Unlike the harmful kind of enlargement seen in certain heart diseases, this is actually a healthy adaptation that helps the heart pump blood more efficiently during regular exercise.

The researchers also examined what was happening at the molecular level.

They found that swimming caused greater changes in several biological pathways that control healthy heart growth. These pathways help heart muscle cells grow, repair themselves, and respond to physical activity.

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The researchers also observed changes in several small molecules known as microRNAs, which help regulate how genes work. These changes were more noticeable in the swimming group, suggesting that swimming may trigger stronger biological responses linked to heart health.

For now, the study adds to a growing pile of evidence that different kinds of endurance exercise can affect the heart in different ways. It also drives home the point that exercise isn’t just about burning calories or getting fitter. It can actually change how the heart grows, works, and adapts over time.

(This article has been curated by Paramita Datta, who is an intern with The Indian Express)