Swimming may be better for your heart than running. The reason is surprising

Swimming equaled running in fitness gains, but led to greater cardiac growth and more favorable molecular changes, which could potentially make it more beneficial for cardiovascular health.

For decades, swimming and running have been considered two of the best forms of aerobic exercise for cardiovascular health.

But a new study, recently published in Scientific Reports, suggests that perhaps not strengthen the heart in exactly the same way.

In a study carried out with an animal model, Brazilian scientists discovered that swimming caused more extensive changes on the structure and function of the heart than running, pointing to distinct biological pathways by which different forms of exercise shape cardiovascular health.

The researchers, from the Federal University of São Paulo (UNIFESP), discovered that swimming was more effective promote healthy heart growth and increase the force with which the heart muscle, or myocardium, contracts.

“Swimming and runningThese are two excellent ways to improve health cardiorespiratory and protect the heart muscle, but we wanted to know if one of them could be even more beneficial than the other”, he says Andrey Jorge Serraprofessor at UNIFESP and coordinator of the study, cited by .

“We discovered that, although both increase respiratory capacity, the swimming goes further, to combine functional adaptations and molecular that make the heart stronger and more efficient”, adds the researcher,

The results of the study showed that swimming had a stronger effect on small molecular regulators, the microARNswhich help the heart adapt to exercise.

These changes seem favor several mechanisms associated with a more resilient and efficient heart: healthy growth of heart cells, formation of new blood vessels, protection against cell death, better regulation of heart muscle contraction and response to oxidative stress. The effects were more pronounced than those observed with running.

How swimming influences heart microRNAs

MicroRNAs are molecules that regulate the expression of messenger RNAsresponsible for protein synthesis.

“Although several studies have already analyzed the expression of microRNAs regulated by aerobic training in general, little was known about the expression patterns when swimming and running were compared in the same experimental context. Therefore, this study reveals that there is a difference in cardiovascular effects of these two modalities”, explains Serra.

In the experiment, mice followed an eight-week training program, with 60-minute exercise sessions, five days a week. The animals were divided into three groups: a sedentary group, a running group and a swimming group.

Because swimming and running are fundamentally different activities, researchers compared them based on relative exercise intensityand not in speed.

Intensity was measured through maximum oxygen consumption, or VO₂ maxa standard indicator of the body’s ability to capture, transport, and utilize oxygen during physical activity.

Both forms of exercise improved physical fitness in a similar way. The VO₂ max. increased by more than 5% between the beginning and end of the training period in both groups that exercised.

However, only swimming produced significant structural changes in the heart, including increases in total cardiac mass and left ventricular mass. Running did not result in relevant differences compared to sedentary animals.

“The choice of a sport depends, to a large extent, on the personal preference, fitness and pleasure that each person takes from practice”, explains the researcher.

“But our results show that swimming can have a special impact in situations involving myocardial recovery, cardiac rehabilitation and, mainly, scientific research”, he adds.

“This is also relevant because studies on aerobic exercise often use running and swimming as if they were equivalentand now we know that the effects nare not the same”, highlights Serra.

“Although we still do not know why this change occurs at the molecular level, at the level of microRNAs, we have managed to deepen research into the molecular pathways that control physiological hypertrophy”, concludes the researcher.