ASSOCIATION OF CHANGES IN SPATIOTEMPORAL VARIABLES AT EACH STEP WITH 100-M SPRINT PERFORMANCE IN PREADOLESCENT SPRINTERS

The purpose of this study was to investigate the association of acceleration and changes in spatiotemporal variables at each step with 100-m sprint performance in preadolescent sprinters. Twenty-six boys performed 100-m sprints, and their spatiotemporal variables were measured at each step. Acceleration was negatively correlated with the 100-m sprint time from the 1st to 21st step. The rates of change in step frequency were positively correlated with acceleration at the 2nd and 3rd step. Posterior to 3rd step, rates of change in step length were positively correlated with acceleration. The results suggest that the acceleration caused by increase in step frequency and step length up to reaching to the maximal sprint velocity is effective for improving the 100-m sprint time

Effects of High Intensity Interval Training on Executive Function in Children Aged 8–12 Years

This study investigated the effects of a high intensity interval training (HIIT) program on both physical fitness and executive functions in children. Fifty-six children aged 8–12 years participated in this study, and were divided into a HIIT group and a control group. The HIIT group performed three sessions of the 8- to 10-min HIIT program per week for 4 weeks. Before and after the intervention, 20-m shuttle runs, sit-ups, and standing long jumps were assessed as test of physical fitness. In addition, the executive function was assessed using the digit span forward (DSF) test, digit span backward (DSB) test, and Tower of Hanoi test. Only the HIIT group experienced significant improvement when completing the 20-m shuttle run (p = 0.042) and sit-ups (p < 0.001). Regarding executive function, the number of correct answers in DSB test significantly increased only in the HIIT group (p = 0.003). However, the standing long jump, DSF, and the Tower of Hanoi test performance did not change after intervention. The findings of the present study suggest that HIIT has positive effects on a core executive function such as working memory in addition to components of the physical fitness such as cardiorespiratory endurance and muscular endurance