Document Type : Research Paper
Authors
1 School of Health and Sport Sciences, Liverpool Hope University, Liverpool, UK
2 Faculty of Motor Sciences, Universite Libre de Bruxelles, Belgium,
3 Department of Exercise Physiology, Faculty of Physical Education and Sport Sciences, Allameh Tabataba’i University, Tehran, Iran.
Abstract
Purpose: The plasticity of the pre-adolescent cardiovascular system in response to structured endurance training remains incompletely characterized. Swimming, a unique volume-load stimulus, may promote beneficial cardiac remodeling in children, but data are scarce. This study aimed to investigate the effects of a 12-week swimming training program on cardiac structure and function in healthy, pre-adolescent boys. Method: In this study, twenty third-grade male students (age: 9.5 ± 0.5 years) were allocated to either a swimming group (Exer, n=10) or a control group (CON, n=10). The Exer group underwent a supervised swimming program (3 sessions/week, 45-60 min/session), while the CON group maintained usual activity. Echocardiographic assessments of cardiac structure (LV end-diastolic dimension [LVEDd], volume [LVEDV], mass [LV mass]) and function (stroke volume [LVSV], cardiac output [LVCO], ejection fraction [LVEF]) were performed pre- and post-intervention. Anthropometric and physiological data, including maximal oxygen consumption (VO₂max), were also collected. Results: Adherence to the training was excellent (>95%). Significant pre-to-post improvements were observed within the Exer group, including increased LVEDd (p=0.016), LVEDV (p=0.002), LV mass (p=0.001), and LVSV (p=0.006). Resting heart rate decreased and estimated VO₂max increased significantly in the Exer group (p<0.05). No significant within-group changes occurred in the CON group. Between-group analysis indicated a significant interaction effect for LVEF (p=0.044), though post-hoc analysis attributed this to a change within the SWIM group. Conclusion: A 12-week swimming training program induces significant, favorable adaptations in cardiac structure and function in pre-adolescent boys, characterized by eccentric remodeling and enhanced stroke volume. These findings demonstrate the trainability of the pre-adolescent heart and underscore the role of swimming as an effective exercise modality for promoting cardiovascular health in youth.
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