Phase composition of the 50-m sprint performed by elementary school students from the viewpoint of changes in running velocity

Abstract

 This study aimed to clarify the composition of the phases (acceleration, full sprint, and velocity endurance) in the 50-m sprint as performed by elementary school students, focusing on changes in running velocity. The subjects were 169 boys and 178 girls in the first to sixth grades of elementary school, who performed a 50-m sprint from a standing start. Running velocity was measured using a laser distance meter, which was synchronized with a video camera that recorded the entire sprint. It was found that the running time of the total sprint was significantly shorter and that maximal velocity was significantly higher for higher-grade than for lower-grade students. The distances of the acceleration phase and full sprint phase were significantly longer for higher-grade than for lower-grade students, but there was no significant difference in the duration of these phases by grade. However, both the distance and duration of the velocity endurance phase were significantly shorter for higher-grade than for lower-grade students. Step length in the acceleration, full sprint, and velocity endurance phases was longer for higher-grade than for lower-grade students. However, step frequency at each phase tended to be almost equal or slightly lower for higher-grade than for lower-grade students. The SL index for higher-grade boys tended to be higher than for lower-grade boys. However, for girls, there was little difference in the SL index at each phase for second-grade students or above. Taken together, the results indicate that the velocity endurance phase comprises the majority of the 50-m sprint when performed by lower-grade students. However, for higher-grade students, the velocity endurance phase is shorter due to the relative increases in the acceleration and sprint phases. This suggests that the distance of the acceleration and full sprint phases affects the distance and duration of the velocity endurance phase.