Autonomic dysfunction as a possible cause of sudden cardiac death in swimming sports.

Introduction: Human diving reflex is a well-studied phenomenon. However, very little is known about the possible relationship between augmented diving reflex and autonomic dysfunction. Methods: We retrospectively studied a group of four swimmers who underwent a diving reflex test as part of the examination due to symptoms related to autonomic dysfunction during swimming. The control group comprised 11 healthy swimmers with no history of these symptoms. A standardized diving reflex test was performed for each athlete in both groups. Hemodynamic profiles, including heart rate, stroke volume, and cardiac output, were recorded. Results: There were no statistically significant differences between the groups in any of the three parameters measured before the test. However, at the end of the test, each parameter (heart rate, stroke volume, and cardiac output) was significantly lower in the swimmers who presented with clinical symptoms related to autonomic dysfunction than in the control group. Conclusion: This observation could shed light on autonomic dysfunction as a possible cause of sudden cardiac death in swimming athletes. It also demonstrated that autonomic dysfunction is presented not only by decreased heart rate but also by stroke volume, causing a drop in cardiac output to the level of hemodynamic collapse.

Body morphology and handgrip strength parameters of the female canoe slalom paddlers.

Introduction: Canoe slalom is a physically very demanding discipline, in which body constitution, body composition, and relative strength are significant factors in high performance. Although anthropometric and strength parameters are relatively well-studied in male athletes, there is a lack of evidence for any conclusions in women. Therefore, the objective of this study was to determine the morphology and upper-limb strength parameters of female canoe slalom paddlers and identify whether morphological differences exist between performance groups. Methods: Altogether, 63 female competitors of the 2023 ICF Canoe Slalom World Cup (n = 29) and 2023 ICF Canoe Slalom World Ranking Competition (n = 34) in Prague (Czech Republic) were examined with a battery of anthropometric tests, segmental bioimpedance analysis, and handgrip strength test. The athletes were divided into groups according to age and performance: elite athletes belonging to the world top 10 according to the ICF World Ranking (WORLD, n = 7), international-level athletes competing during the World Cup (ELITE, n = 22), international-level junior athletes competing in the World Ranking Race (JUNIOR, n = 17), and other lower performance-level athletes competing in the World Ranking Race (REST, n = 17). Results: Female slalom paddlers are, in general, of average body height (∼165 cm), lower body mass (∼60 kg), BMI (∼22 kg/m2), and body fat (∼20%) and without exceptional anthropometric dimensions and proportions. However, differences were detected when performance was factored in. Female paddlers belonging to the world TOP 10 have the largest circumferences of arms and forearms, and their somatotype is more mesomorphic, with a lower proportion of total body fat and a higher proportion of muscle mass. In addition, the WORLD group differs significantly in upper-limb strength. Discussion: The results shows the significance of muscular strength and power for canoe slalom athletes and the importance of well-developed musculature in operating the boat in the unstable environment. Being a successful female canoe slalom athlete requires a well-developed musculature, maximizing strength capabilities while maintaining a low body weight through limited hypertrophy of the lower limbs and a low level of body fat.