Age-Related Changes in Standing Sprint Start Performance and Posture in Sprinting.

The relationship between upper- and lower-limb positioning during standing sprint starts and acceleration performance across developmental stages remains unclear. The purpose of this study was to categorize the standing sprint start postures of participants ranging from elementary school to university students and to examine how these postures influence the time from the start signal to the first foot contact and the 5-m split time during a 50-m sprint. Starting postures were classified as Type A (same-side arm-leg alignment) or Type B (opposite-side arm-leg alignment). Two-way ANOVA revealed a significant main effect for posture type, indicating that Type B generally resulted in a shorter initial acceleration time than did Type A. Furthermore, a significant interaction effect was found for the 5-m split time for boys, with a particularly pronounced trend of decreasing times from lower elementary school to junior high school grades. These findings suggest that contralateral arm-leg positioning during standing sprint starts is associated with early acceleration performance and may reflect developmental changes in coordination relevant to sprint performance and coaching practice.