Table 1 Descriptive characteristics of the study population and times spent in sedentary behaviors
| Â | Number | Percent |
|---|---|---|
Overall | 625 | 100.0 |
Okayama in 2010 | 303 | 48.5 |
Tokyo in 2014 | 322 | 51.5 |
Sex | ||
 Male | 330 | 52.8 |
 Female | 295 | 47.2 |
Grade level | ||
 Lower grades | 173 | 27.7 |
 Higher grades | 452 | 72.3 |
Body mass index (kg/m2) | ||
 Mean ± SD | 16.9 ± 2.7 | |
 Z score (median, 25 to 75%ile) | −0.19, −0.65 to 0.40 | |
Sedentary time, min/week | ||
 Weekdays | Mean ± SD | |
  Reading or listening to music | 90.3 ± 123.4 | |
  TV or video viewing | 535.0 ± 356.6 | |
  TV game use | 167.3 ± 222.1 | |
  Computer use excluding class | 23.9 ± 70.9 | |
  Doing homework or assignments | 264.9 ± 185.3 | |
  Car travel | 33.4 ± 61.2 | |
 Weekends | Mean ± SD | |
  Reading or listening to music | 42.1 ± 70.0 | |
  TV or video viewing | 323.9 ± 232.0 | |
  TV game use | 123.0 ± 96.4 | |
  Computer use excluding class | 15.8 ± 49.9 | |
  Doing homework or assignments | 74.4 ± 96.4 | |
  Car travel | 71.3 ± 84.9 | |
Physical activitya, number of days/week | ||
 Mean ± SD | 3.0 ± 2.2 | |
 Z score (median, 25 to 75 percent tile) | −0.12, −0.82 to 0.77 | |