The purpose of this study was to investigate cross-sectionally the development of running speed, step frequency, step length, running form, and maximal anaerobic power (MAnP) in high school girls. Subjects were 130 high school girls ranging from fifteen to seventeen years of age. They participated in power tests including 50 m dash, maximal bicycle pedalling, vertical jump and long jump and measurement of subcutaneous fat's thickness. They were videotaped during 50 m dash to analyze their running form. Variables analyzed were: 1) 50 m running time, running speed, step frequency and step length, 2) step time, support time and non-support time, 3) path of the whole body center of gravity (CG), 4) maximal anaerobic power, %Fat, vertical jump, and long jump. The results were summarized as follows: 1. The running time for 50 m, running speed, step frequency and step length showed no significant change with age. 2. MAnP decreased from 513.3 W to 484.5 W with age, and MAnP/body weight decreased from 9.68 W/kg to 9.29 W/kg with age, but both of them showed no significant change. 3. At each age, significant correlations were found between running speed and step frequency, step length, step length/body height except step frequency of fifteen-year-old girls. Furthermore, running speed and variables for physical fitness such as MAnP showed significant correlations except vertical jump of sixteen-year-old girls. Running speed and %Fat showed a significant negative correlation for each age-group. The MAnP/body weight and vertical jump, long jump showed a significant correlation for each age-group. 4. The relationship between running speed and the CG motion indicated that it was important to shorten support time and reduce the bouncing motion of the CG in order to improve running speed. The relationship between running speed and the motion of the lower limbs suggested that motion of the toe relative to the hip during support phase, forward motion of the free leg and backward swing motion of the toe prior to foot contact at high speed help to improve running speed. This relationship between running speed and running form is the same characteristic with high school boys. 5. Based on the averages and the standard deviations of variables examined for each age group, running performance was classified into five categories. The averages of step frequency, step length, step length/body height, MAnP/body weight, vertical jump, long jump and %FAT for the categories were listed in Table 7. This will be useful to evaluate running performance of students and teach sprint running in physical education classes.
