A longitudinal study on development of sprinting performance for junior high school boys

This study investigated through a first grade at a junior high school boy child and, until third grade time after two year, analyzed sprinting performance for 46 people. They were filmed in VTR picture during 50m sprinting. Using the VTR pictures, we calculated average speed, step frequency and step length. The results obtained were as follows: 1 It can be judged that the increased sprinting velocity cause by increased step length and no change of step frequency from first grade to third grade. 2 The student who was the height growth spurt time was able to be classified into four groups, G 1 : the group with the earliest growth that has already passed PRV age, and ends growth, G 2: the group with an early growth in second and the growth speed is slowing gradually height velocity, G 3 : the group in the PHV amount age, G 4 : the group that grows slowly a~d the growth spurt starts. 3 As for G 1 thought to be precocious, 50m run time of second grade had quickened more than the time of first grade and There was no difference with the time of third grade. G 2 has quickened in the passing age. The differel)ce is not statistically seen first and second grade respectively as for G 3 and G4, and third grade has quickened respectively. 4 It was suggested that the level of the participation of the step length and the step frequenc different according to the growth stage in shortening 50m run at time