Association between daily physical activity and fitness in junior high school students

The purpose of this study was to assess daily physical activity and time spent on activities of various intensities, and to examine the relationship between daily physical activity and physical fitness in junior high school students. The subjects were 314 junior high school students (135 boys, 179 girls, 14.0±0.1 years). Daily physical activity was evaluated using accelerometers that they wore around the waist for 10 days. The accelerometers calculated steps and time spent on activities of vigorous intensity (LC7-9: higher intensity than brisk walking). A physical fitness test (8 items) was employed to evaluate the fitness of pupils. The total accelerometer steps (counts/day) were 13772±4764 for boys and 11209±2636 for girls on weekdays, and 8311±4743 for boys and 7159±3338 for girls on weekends, respectively. On weekdays, time spent on activities with an intensity of LC7-9 (minutes/day) was 18±17 for boys and 11±7 for girls. Positive associations were found between physical fitness and daily physical activities in the case of many items. The fitness test score was significantly more highly correlated with LC7-9 than with LC1-6 in boys and girls. In the case of eighth graders, in order to reach a score of B in the physical fitness test, it was suggested that the total steps and time spent on activities with an intensity of LC7-9 may be needed at least 13000 steps and 20 minutes in boys, and 10000 steps and 10 minutes in girls, respectively.