Research shows swimming promotes superior heart growth and beneficial molecular changes in mice — Evidence Review
Published in Scientific Reports, by researchers from Federal University of São Paulo (UNIFESP)
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Table of Contents
Swimming may offer greater heart growth and more favorable molecular changes than running, according to a recent animal study; related research generally supports unique cardiac adaptations from swimming. Most comparative studies find both exercises beneficial, but several highlight swimming's distinct effects on heart structure and molecular pathways, including microRNA regulation, autonomic balance, and vascular remodeling (1, 2, 5, 9).
- Research shows swimming induces pronounced cardiac hypertrophy and vagal activity, differing from running, and is linked to improved cardiac function and longevity in animal models (1, 9).
- Studies emphasize that aerobic exercise, especially swimming, regulates specific microRNAs involved in healthy heart growth, angiogenesis, and stress responses, supporting the current findings (2, 5).
- Population-level and mechanistic studies suggest swimming may confer cardiovascular risk reduction and distinct vascular benefits compared to running, though both have positive health impacts (6, 7, 8).
Study Overview and Key Findings
With aerobic exercise widely recommended for heart health, understanding how different activities uniquely affect the cardiovascular system is increasingly relevant. This study from the Federal University of São Paulo focuses on comparing the cardiac effects of swimming versus running, not only at the functional level but also at the tissue and molecular scale, using a controlled animal model. The research is notable for examining how these two popular forms of exercise drive specific biological adaptations, particularly in heart structure and microRNA expression, which may have implications for cardiac rehabilitation and disease prevention.
| Property | Value |
|---|---|
| Study Year | 2026 |
| Organization | Federal University of São Paulo (UNIFESP) |
| Journal Name | Scientific Reports |
| Authors | Amanda Yoshizaki, Ednei Luiz Antonio, Luis Dos Santos, Mariana Teixeira dos Santos, Flavia Leticia Martins, Regiane Santos Feliciano, Jose Antonio Silva Junior, Brunno Lemes de Melo, Danilo Sales Bocalini, Paulo José Ferreira Tucci, Adriana Castello Costa Girardi, Andrey Jorge Serra |
| Population | Mice |
| Methods | Animal Study |
| Outcome | Heart structure and function changes, microRNA expression |
| Results | Swimming produced greater heart growth and favorable molecular changes. |
Literature Review: Related Studies
To contextualize these findings, we searched the Consensus paper database (over 200 million research papers) using targeted queries to identify relevant comparative and mechanistic studies. The following search queries were used:
- swimming heart growth benefits
- cardiovascular effects swimming versus running
- molecular changes swimming exercise advantages
| Topic | Key Findings |
|---|---|
| How do swimming and running differ in cardiac adaptations? | - Swimming produces more pronounced cardiac hypertrophy and vagal activity compared to running, influencing resting heart rate and cardiac structure (1, 9). - Both swimming and running improve cardiovascular fitness, but swimming may drive unique molecular and tissue-level changes (1, 2, 9). |
| What is the role of microRNAs and molecular pathways in exercise-induced heart growth? | - Aerobic exercise, especially swimming, regulates a set of microRNAs associated with beneficial heart remodeling, angiogenesis, and reduced fibrosis (2, 5). - Exercise-driven cardiac hypertrophy involves activation of pathways such as AKT and CITED4, with lymphangiogenesis contributing to physiological cardiac growth (2, 5). |
| Does swimming confer unique cardiovascular or mortality benefits in humans? | - Swimming is associated with reduced cardiovascular disease mortality and may help preserve arterial compliance more effectively than a sedentary lifestyle or even running (6, 7, 8). - While both swimming and running lower mortality risk, only swimming shows significant associations with reduced cardiovascular mortality in some cohort studies (7). |
| What are the physiological and nervous system effects of swimming vs. running? | - Swimming enhances parasympathetic (vagal) activity and may activate the sympathetic nervous system differently from running, leading to distinct autonomic and hematological adaptations (1, 9, 10). - Both exercise types lower heart rate and improve heart rate variability, but underlying regulatory mechanisms may differ (1, 9, 10). |
How do swimming and running differ in cardiac adaptations?
The new study's findings that swimming leads to greater heart growth and distinctive adaptations compared to running are consistent with prior research. Animal studies have shown that swimming induces more significant cardiac hypertrophy and increases in vagal tone, contributing to lower resting heart rates and improved cardiac function—effects less pronounced or mechanistically different in running models (1, 9). These adaptations may be especially relevant for cardiac rehabilitation and disease prevention.
- Swimming training leads to increased heart mass, myocyte size, and vagal modulation in rats, supporting the new study's results (1).
- Running and swimming both improve fitness, but swimming induces more substantial heart structure changes in animal models (1, 9).
- Distinct cardiovascular physiological adaptations occur with each exercise, underlining the importance of exercise modality selection in research and clinical practice (9).
- Both exercises improve lipid profiles and VO₂ max, but the patterns of autonomic and structural adaptation differ (1, 9).
What is the role of microRNAs and molecular pathways in exercise-induced heart growth?
The current research highlights that swimming more strongly influences the expression of microRNAs involved in cardiac growth, angiogenesis, and protection against cell death, compared to running. This is well supported by literature showing that aerobic exercise, particularly swimming, modulates both antihypertrophic and prohypertrophic microRNAs, which orchestrate healthy cardiac remodeling and angiogenesis (2, 5). Additionally, molecular pathways such as AKT activation and CITED4 signaling are implicated in exercise-induced physiological hypertrophy, with lymphangiogenesis playing a crucial role (5).
- Swimming regulates a broader array of microRNAs involved in heart growth and angiogenesis than running (2).
- Key molecular mechanisms such as AKT and CITED4 activation, and increased lymphangiogenesis, are necessary for healthy cardiac growth induced by swimming (5).
- MicroRNA shifts associated with swimming can reduce fibrosis and promote new blood vessel formation, supporting improved cardiac function (2).
- The new study’s focus on microRNA expression provides mechanistic insight into how exercise modality affects cardiovascular adaptations (2, 5).
Does swimming confer unique cardiovascular or mortality benefits in humans?
Evidence from human studies indicates that swimming is linked to reduced cardiovascular disease mortality and preservation of arterial compliance, with some studies reporting stronger associations for swimming than for running (6, 7, 8). Swimming is characterized as a unique exercise modality with distinctive physiological effects due to water immersion, which may explain some of these differences. Cohort studies suggest that swimming, along with certain other sports, is associated with lower all-cause and cardiovascular mortality, while running does not consistently show the same association (7).
- Participation in swimming is associated with significant reductions in all-cause and cardiovascular mortality, while running does not always show this benefit (7).
- Regular swimming helps maintain central arterial compliance and may prevent vascular stiffness in middle-aged and older adults (6).
- The unique properties of swimming, such as immersion and breathing patterns, may contribute to its cardiovascular benefits (8).
- Both swimming and running are beneficial, but the magnitude and nature of benefits may differ depending on the health outcome measured (7, 8).
What are the physiological and nervous system effects of swimming vs. running?
Distinct autonomic and hematological adaptations have been observed between swimming and running. Swimming tends to enhance parasympathetic (vagal) activity and can increase sympathetic nervous system activation, while running more strongly affects serotonergic modulation (1, 9, 10). Both modes of exercise lead to reduced heart rate and improved heart rate variability, but the underlying regulatory mechanisms and the extent of the changes may vary.
- Swimming induces greater cardiac vagal activity and resting bradycardia, which are linked to longevity and cardiac event prevention (1).
- Swimming and running both increase heart rate variability, but their effects on nervous system regulation differ (10).
- Hematological adaptations, such as changes in red blood cell profiles and platelet aggregation, have been observed with each exercise, with swimming showing unique patterns (9).
- Understanding these differences is important for selecting exercise interventions tailored to specific cardiovascular or autonomic outcomes (1, 9, 10).
Future Research Questions
While the current study provides valuable insights into the distinct cardiovascular adaptations induced by swimming and running, important questions remain. Further research is needed to clarify the long-term implications of these adaptations in humans, investigate molecular mechanisms in greater detail, and understand how individual factors may influence responsiveness to different exercise modalities.
| Research Question | Relevance |
|---|---|
| Do the distinct cardiac adaptations from swimming translate to greater clinical benefits in humans? | Animal studies show pronounced cardiac hypertrophy and molecular changes from swimming, but human data on clinical outcomes and long-term cardiac health are less conclusive (1, 6, 7). Further research could clarify the clinical significance of these adaptations. |
| How do different intensities and durations of swimming and running affect cardiac molecular pathways? | Exercise intensity and duration are known to influence physiological and molecular adaptations, but the specific effects for each modality on microRNAs and signaling pathways require further study (2, 5, 9). |
| What are the effects of swimming versus running in cardiac rehabilitation patients? | The new findings suggest swimming may be especially beneficial for myocardial recovery and rehabilitation, but clinical trials are needed to assess efficacy and safety in patients with heart disease (8). |
| Which genetic or individual factors influence the response to different exercise modalities? | Molecular responses to exercise, including microRNA regulation, may vary by genetics, age, sex, or underlying health status; personalized exercise prescriptions could optimize benefits (2, 14). |
| Can the molecular pathways activated by swimming be targeted therapeutically for heart disease? | Understanding which molecular pathways are uniquely activated by swimming could inform new therapies for promoting physiological cardiac growth or recovery after injury (2, 5). |