Cross-Sectional Body Composition Analysis in Distinct Union Cycliste Internationale Categories of Male Road Cyclists: A Multimodal Approach

Background: Body composition is a key determinant of performance in road cycling. However, field-based, multimodal analyses of body composition across different competitive age categories are lacking. This study aimed to investigate body composition and performance metrics using portable assessment tools in Junior, Under-23, and Professional categories of male road cyclists of the Union Cycliste Internationale. Methods: In this observational cross-sectional study, 62 male road cyclists underwent body composition assessment via bioelectrical impedance vector analysis and B-mode ultrasonography to evaluate subcutaneous adipose tissue (SAT) thickness and thigh muscle architecture. Field-based performance parameters, critical power (CP) and anaerobic work capacity (W′), were derived from power meter data collected over 60 days. Results: Professional cyclists exhibited significantly lower SAT thickness at several limb sites with higher impedance vector length (Z/h), indicating reduced total body water compared with Junior cyclists. No significant differences in muscle architecture were observed across categories. Professional cyclists demonstrated superior absolute and relative CP and W′. Across all cyclists, lower SAT thickness and phase angle, and higher Z/h, were associated with better endurance performance. Muscle thickness and architecture of the vastus lateralis and rectus femoris were positively associated with W′ and absolute CP. Conclusion: Higher-level cyclists exhibit a body composition profile characterized by lower SAT and reduced total body water, which correlates with performance indexes. The combined use of bioelectrical impedance vector analysis and ultrasonography provides a practical, field-based approach for monitoring body composition in road cyclists, supporting tailored training and nutritional strategies.