論文

In aesthetic sports, performance is closely linked to body composition; however, quantitative indicators for monitoring athlete conditions remain limited. Bioelectrical impedance analysis-derived phase angle (PhA) reflects cellular health; however, its relationship with performance-related variables in rhythmic gymnasts remains unclear. This study explored the relationships among PhA, body composition, bone density, training time, and jump performance in senior rhythmic gymnasts across competitive levels. Twenty-three female gymnasts (aged 15–22 years) were classified into a top group consisting of athletes who had won major domestic competitions in Japan (n = 5) and a general group (n = 18). Body composition and PhA were assessed using bioelectrical impedance analysis, jump performance using the countermovement jump and reactive strength index, and bone density using the calcaneal ultrasound method. Although between-group differences were limited, distinct associations between PhA and performance-related variables were observed only in the top group. PhA was positively associated with skeletal muscle mass. In addition, a moderate, non-significant negative association between PhA and countermovement jump performance was observed in the top group. No clear relationships between PhA and body composition or jump performance were observed in the general group. Although these findings should be interpreted cautiously because of the small sample size and exploratory nature of the study, they suggest that the associations between PhA and performance-related variables may differ according to competitive level. Further studies with larger sample sizes and longitudinal designs are needed to clarify the relationships between PhA, performance-related variables, and physiological condition in rhythmic gymnasts.