Table 1. The characteristics of the subjects. Data are expressed as mean ± SD or N (%).
| Variables |
Boys (n = 39,612) |
Girls (n = 35,454) |
Total (n = 75,066) |
| Age (years) |
015.00 ± 1.73 |
015.12 ± 1.77 |
015.06 ± 01.75 |
| Height (m) |
1.70 ± .09 |
160 ± .05 |
165 ± 0.08 |
| Weight (kg) |
060.14 ± 11.72 |
051.47 ± 7.67 |
056.04 ± 10.91 |
| Body mass index (kg/m2) |
020.80 ± 03.21 |
020.05 ± 2.58 |
020.45 ± 02.95 |
| Family’s economic status N (%) |
Very rich |
02,923 (7.4) |
01,434 (4.0) |
04,357 (5.8) |
| Rich |
08,985 (22.7) |
06,908 (19.6) |
15,893 (21.2) |
| Average |
17,743 (44.7) |
17,706 (49.9) |
35,449 (47.2) |
| Poor |
07,150 (18.1) |
07,090 (20.0) |
14,240 (19.0) |
| Very poor |
02,811 (7.1) |
02,316 (6.5) |
05,127 (6.8) |
| Father’s education level N (%) |
Unknown |
07,297 (18.4) |
05,321 (15.0) |
12,618 (16.8) |
| Middle school or lower |
02,707 (6.8) |
02,483 (7.0) |
05,190 (6.9) |
| High school |
14,294 (36.1) |
13,915 (39.2) |
28,209 (37.6) |
| College or higher |
15,314 (38.7) |
13,735 (38.8) |
29,049 (38.7) |
| Mother’s education level N (%) |
Unknown |
08,069 (20.4) |
05,059 (14.3) |
13,128 (17.5) |
| Middle school or lower |
02,447 (6.2) |
02,490 (7.0) |
04,937 (6.6) |
| High school |
17,745 (44.7) |
18,212 (51.4) |
35,957 (47.9) |
| College or higher |
11,351 (28.7) |
09,693 (27.3) |
21,044 (28.0) |
| School performance N (%) |
Very good |
04,958 (12.5) |
03,454 (9.7) |
08,412 (11.2) |
| Good |
09,172 (23.2) |
08,411 (23.7) |
17,583 (23.4) |
| Average |
10,544 (26.6) |
09,675 (27.3) |
20,219 (26.9) |
| Poor |
09,661 (24.4) |
09,477 (26.7) |
19,138 (25.5) |
| Very poor |
05,277 (13.3) |
04,437 (12.5) |
09,714 (12.9) |
| The number of PE classes attended per week N (%) |
No PE class |
03,133 (7.9) |
03,988 (11.2) |
07,121 (9.5) |
| Once per week |
03,231 (8.2) |
03,376 (9.5) |
06,607 (8.8) |
| Twice per week |
19,138 (48.3) |
16,271 (45.9) |
35,409 (47.2) |
| ≥3 classes per week |
14,110 (35.6) |
11,819 (33.3) |
25,929 (34.5) |
| City size N (%) |
Large cities |
21,014 (53.0) |
18,273 (51.5) |
39,287 (52.3) |
| Middle-sized cities |
13,802 (34.9) |
12,605 (35.6) |
26,407 (35.2) |
| small-sized cities |
04,796 (12.1) |
04,576 (12.9) |
09,372 (12.5) |
| Grade N (%) |
Middle school first |
06,933 (17.5) |
05,781 (16.3) |
12,714 (16.9) |
| Middle school second |
06,965 (17.6) |
05,903 (16.6) |
12,868 (17.1) |
| Middle school third |
07,035 (17.7) |
05,792 (16.3) |
12,827 (17.1) |
| High school first |
06,890 (17.4) |
05,587 (15.8) |
12,477 (16.6) |
| High school second |
06,104 (15.4) |
06,323 (17.9) |
12,427 (16.6) |
| High school third |
05,685 (14.4) |
06,068 (17.1) |
11,753 (15.7) |
BMI, Body Mass Index; PE, Physical Education.
