Swimming May Be Better Than Running for Heart Health, Study Suggests

New research is drawing attention to how different forms of exercise may influence the heart in distinct ways, with swimming emerging as a particularly powerful activity for cardiovascular health. Scientists have found that while both swimming and running improve overall fitness, swimming may trigger deeper structural and biological changes in the heart.

Research Background and Expert View

The study was carried out by Professor Andrey Jorge Serra and his team at the Federal University of São Paulo (UNIFESP). He noted that both swimming and running contribute positively to heart and lung performance, yet swimming appears to offer additional benefits that go beyond basic fitness improvements.

According to Serra, swimming not only enhances endurance but also promotes internal adaptations that strengthen the heart’s efficiency and function at a biological level.

How the Study Was Conducted

Published in the journal Scientific Reports, the findings were based on an animal experiment involving mice. Over a period of eight weeks, the animals trained for one hour per day, five days a week.

The mice were divided into three groups: one group remained inactive, another followed a running routine, and the third participated in swimming sessions. To fairly compare the effects of these different activities, researchers measured VO₂ max, a standard indicator of how effectively the body uses oxygen during exercise.

Main Outcomes of the Experiment

Results showed that both running and swimming improved overall fitness, with VO₂ max rising by more than five percent in each active group. However, significant differences appeared when examining heart structure.

Only the swimming group displayed noticeable changes in cardiac development. These mice experienced an increase in overall heart size as well as growth in the mass of the left ventricle, the chamber responsible for pumping oxygen-rich blood throughout the body. Such changes were not observed in the running group, whose heart structure remained similar to that of inactive mice.

Changes at the Molecular Level

The study also explored how exercise influenced microRNAs, tiny molecules that regulate protein production and gene activity in the body.

Swimming had a stronger effect on these molecular regulators, influencing processes linked to heart cell growth, formation of new blood vessels, protection against cellular damage, and improved contraction efficiency. These findings suggest that swimming may stimulate more advanced and complex adaptations within the heart compared to running.

Broader Scientific Implications

Further analysis looked into gene expression patterns and protein pathways associated with healthy heart development. Although researchers have not yet fully explained why swimming produces these distinct molecular responses, the results provide valuable insight into how different types of aerobic exercise shape the heart in unique ways.

Professor Serra also highlighted that most individuals choose physical activities based on enjoyment and personal preference. However, these findings suggest that swimming could hold special value, particularly in contexts such as cardiac rehabilitation and recovery programs. The research challenges the long-standing assumption that all aerobic exercises affect the heart in the same manner.