SECULAR CHANGE IN RUNNING PERFORMANCE OF JAPANESE ADOLESCENTS - A LONGITUDINAL DEVELOPMENTAL-STUDY

A 5-year longitudinal cohort study of the running development of Japan ese adolescents was conducted at a secondary school in Tokyo from 1968 to 1994. The purpose was to investigate changes in the pattern of dev elopment over time. The test items were an endurance run (1,500 m for boys and 1,000 m for girls) and a dash (50 m for both sexes). The tota l number of subjects was 512 boys and 516 girls in the endurance run, and 825 boys and 895 girls in the dash. These students entered the fir st grade of the school from 1968 to 1989 at the age of 12 years, and w ere followed for the next 5 years. In the analyses, a quadratic regres sion model was used to characterize intraindividual, age-related chang es in running performance. The model fit the observed data, and the va lidity of the model was confirmed. Secular changes in the running deve lopment of boys were minimal over the last 30 years. Changes in girls, however, had three different patterns: 1) an overall decrease in perf ormance with an almost unchanged estimated performance in the first gr ade, 2) a greater decrease in the late-teenage years, and 3) a decreas e in the age of maximal performance. Secular changes in physical growt h (stature and body mass index) could not fully explain the secular ch anges in the running development of girls, suggesting that the underly ing causes may be social and cultural. (C) 1998 Wiley-Liss, Inc.