2015 Volume 60 Issue 2 Pages 497-510
The aim of this study was to clarify the relationship between maximal running speed, step frequency, step frequency index, step length, step length index, foot contact time, and aerial time during sprinting in elementary school children. The participants were 335 girls and 352 boys (age: 6 to 12 years) who ran a 50-m sprint race as part of their school fitness test in 2013. Their maximal running speed, step frequency, and step length were calculated from images captured by video cameras (60 frames/second) located at the sides of the lanes. Contact time and aerial time over the distance from 20 m to 30 m were calculated from images captured by high-speed video cameras (300 frames/second) located at the side of the 25-m mark for the lanes. Two-way ANOVA with the Games-Howell procedure was used to test differences among all grades. Two-way ANCOVA was used to test interaction and the main effect of gender and grade on maximal running speed. The Pearson product-moment correlation coefficient (r) and partial correlation coefficient (pr) were calculated to analyze the relationship between maximal running speed, step frequency, stride length, foot contact time, and aerial time. Step length (which was strongly correlated with maximal running speed) showed a strong partial correlation (controlled for age) with maximal running speed. Therefore, it is suggested that step length contributes to not only the increase in running speed with growth, but also individual differences in running speed among the children at the same age. There were slight tendencies for step frequency and foot contact time to increase with growth. However, these factors showed a significant partial correlation (controlled for age) with running speed. Therefore, it was suggested that these factors contribute to individual differences in running speed. The absence of a negative impact of a shorter foot contact time on stride length suggests that the running performance of school children could be improved by decreasing their foot contact time. In order to establish effective methods for augmenting the development of running ability in children, it will be necessary to consider foot contact time and aerial time in addition to step frequency and step length.
