The irrefutable benefits of physical activity as a tool for the prevention and treatment of several clinical conditions, including cardiovascular diseases, are nowadays widely recognized. However, physical exercise may trigger adverse events in subjects with underlying heart disease, often undiagnosed and asymptomatic. It is fundamental to consider that various sports disciplines have peculiar and specific physiological and metabolic adaptations, and it is essential to consider the individual profile of the subject, including gender. We report the case of an agonistic female swimmer with a history of tachycardia heartbeat when resurfacing from dynamic apnea, in whom a diagnosis of atrioventricular nodal reentrant tachycardia was made. This case report provides practical evidence of the importance of a personalized approach, in both individual sex- and sport-specific terms, to optimize the diagnostic and therapeutic pathways.