Relationship Between Selected Somatic Characteristics and Psychomotor Performance in Members of the National Team in Traditional Karate

Background: In traditional karate, performance effectiveness is determined, among other factors, by the speed of stimulus processing and the precision of the motor response. Body composition may indirectly modulate these abilities; however, data on karate athletes are limited. Methods: The study included 27 men—active members of the Polish national team in traditional karate (18–30 years; training experience ≥ 5 years; black belt). Body composition was assessed using segmental bioelectrical impedance analysis (InBody 770), and psychomotor abilities were measured with the TEST2DRIVE system: SIRT (simple reaction), CHORT (choice reaction), HECTOR (simple reaction), and SPANT (spatial anticipation). Results: The psychomotor profile showed the longest reaction times in CHORT and the shortest in SIRT. Associations with body composition were selective: in SIRT, the median simple reaction time demonstrated a moderate positive relationship with lean-mass-related parameters, with no associations for motor time. No significant correlations with body composition were found in CHORT or HECTOR. In SPANT, significant associations concerned motor time only, which was positively related to selected indices of adiposity and fat distribution, whereas choice reaction time and accuracy were independent of body composition. Conclusion: In traditional karate athletes, body composition is not an unambiguous predictor of psychomotor performance, and its relevance depends on task characteristics. The findings suggest that potential effects of somatic parameters are expressed mainly in selected execution components; therefore, assessments of competitive readiness should combine body composition monitoring with tests that differentiate the reaction phase from the motor phase.