Swimming vs Running: Cardiovascular Effects

A study published on June 19, 2026, in Scientific Reports reveals that while swimming and running provide comparable improvements in overall cardiorespiratory fitness, swimming induces superior structural and molecular adaptations in the heart. Researchers at the Federal University of São Paulo (UNIFESP) found that swimming specifically promotes healthy cardiac hypertrophy and enhances myocardial contractile force more effectively than running. The research team, led by Professor Andrey Jorge Serra, emphasizes that these two aerobic activities utilize distinct biological pathways. While both exercises increased maximum oxygen consumption (VO2 max) by over 5% in an eight-week mouse model, only swimming resulted in significant increases in total heart mass and left ventricular mass, suggesting it may be a more potent intervention for cardiac rehabilitation. The study identifies that swimming triggers specific changes in microRNAs, which are critical regulators of protein synthesis. These molecular shifts facilitate essential cardiovascular processes, including angiogenesis (the development of new blood vessels), protection against programmed cell death, and improved regulation of heart muscle contraction, which were not observed to the same extent in the running group. These findings provide significant practical value for clinical and personal exercise planning. For individuals seeking targeted cardiovascular recovery or enhanced heart efficiency, swimming may offer unique physiological benefits. The study also cautions researchers to avoid using swimming and running interchangeably in future scientific trials, as their distinct cardiovascular impacts could skew experimental results.