Table 1:
The characteristics of subjects
| Variables | Male adolescents (n = 37,873) | Female adolescents (n = 37,770) | Total (n = 75,643) | |
|---|---|---|---|---|
| Age (years) | 15.08 ± 1.75 | 15.12 ± 1.75 | 15.10 ± 1.75 | |
| Height (cm) | 169.90 ± 8.02 | 159.99 ± 5.36 | 164.95 ± 8.43 | |
| Weight (kg) | 60.51 ± 11.67 | 51.84 ± 7.81 | 56.18 ± 10.84 | |
| Body mass index (kg/m2) | 20.86 ± 3.21 | 20.22 ± 2.63 | 20.54 ± 2.95 | |
| School performance Number (%) | Very high | 4,606 (12.2) | 3,707 (9.8) | 8,313 (11.0) |
| High | 8,986 (23.7) | 9,267 (24.6) | 18,253 (24.1) | |
| Average | 10,055 (26.6) | 10,320 (27.3) | 20,375 (26.9) | |
| Low | 9,362 (24.7) | 9,973 (26.4) | 19,335 (25.6) | |
| Very low | 4,864 (12.8) | 4,503 (11.9) | 9,367 (12.4) | |
| Frequency of breakfast consumption per week Number (%) | No breakfast per week | 5,162 (13.6) | 4,187 (11.1) | 9,349 (12.4) |
| 1 day | 1,974 (5.1) | 2,174 (5.8) | 4,121 (5.4) | |
| 2 days | 2,383 (6.3) | 2,626 (7.0) | 5,009 (6.6) | |
| 3 days | 2,579 (6.8) | 2,874 (7.6) | 5,453 (7.2) | |
| 4 days | 2,119 (5.6) | 2,435 (6.4) | 4,554 (6.0) | |
| 5 days | 3,286 (8.7) | 3,789 (10.0) | 7,075 (9.4) | |
| 6 days | 3,606 (9.5) | 4,386 (11.6) | 7,992 (10.6) | |
| Every day | 16,791 (44.3) | 15,299 (40.5) | 32,090 (42.4) | |
| Frequency of smoking Number (%) | No smoking | 31,522 (83.2) | 35,133 (93.0) | 66,655 (88.1) |
| 1–2 day(s) per month | 1,076 (2.8) | 576 (1.5) | 1,652 (2.2) | |
| 3–5 days per month | 477 (1.3) | 260 (0.7) | 737 (1.0) | |
| 6–9 days per month | 405 (1.1) | 177 (0.5) | 582 (0.8) | |
| 10–19 days per month | 493 (1.3) | 244 (0.6) | 737 (1.0) | |
| 20–29 days per month | 563 (1.5) | 250 (0.7) | 813 (1.1) | |
| Every day | 3,337 (8.8) | 1,130 (3.0) | 4,467 (5.9) | |
| Frequency of drinking Number (%) | No drinking | 29,021 (76.6) | 31,028 (82.1) | 60,049 (79.4) |
| 1–2 day(s) per month | 4,607 (12.2) | 4,117 (10.9) | 8,724 (11.5) | |
| 3–5 days per month | 1,734 (4.6) | 1,116 (3.0) | 2,850 (3.8) | |
| 6–9 days per month | 1,120 (3.0) | 668 (1.8) | 1,788 (2.4) | |
| 10–19 days per month | 804 (2.1) | 532 (1.4) | 1,336 (1.8) | |
| 20–29 days per month | 362 (1.0) | 223 (0.6) | 585 (0.8) | |
| Every day | 225 (0.6) | 86 (0.2) | 311 (0.4) | |
| Father’s education level Number (%) | Middle school or lower | 1,843 (4.9) | 1,943 (5.1) | 3,786 (5.0) |
| High school | 12,587 (33.2) | 13,954 (36.9) | 26,541 (35.1) | |
| College or higher | 16,601 (43.8) | 15,908 (42.1) | 32,509 (43.0) | |
| Unknown | 6,842 (18.1) | 5,965 (15.8) | 12,807 (16.9) | |
| Mother’s education level Number (%) | Middle school or lower | 1,765 (4.7) | 2,025 (5.4) | 3,790 (5.0) |
| High school | 16,192 (42.8) | 18,402 (48.7) | 34,594 (45.7) | |
| College or higher | 12,723 (33.6) | 12,022 (31.8) | 24,745 (32.7) | |
| Unknown | 7,193 (19.0) | 5,321 (14.1) | 12,514 (16.5) | |
| Family economic status Number (%) | Very rich | 3,165 (8.4) | 1,612 (4.3) | 4,777 (6.3) |
| Rich | 9,401 (24.8) | 8,253 (21.9) | 17,654 (23.3) | |
| Average | 16,929 (44.7) | 18,833 (49.9) | 35,762 (47.3) | |
| Poor | 6,336 (16.7) | 7,213 (19.1) | 13,549 (17.9) | |
| Very poor | 2,042 (5.4) | 1,859 (4.9) | 3,901 (5.2) | |
| Frequency of vigorous PA Number (%) | No vigorous PA | 6,095 (16.1) | 15,942 (42.2) | 22,037 (11.0) |
| Once a week | 6,414 (16.9) | 7,995 (21.2) | 14,409 (19.0) | |
| Twice a week | 7,481 (19.8) | 6,139 (16.3) | 13,620 (18.0) | |
| Thrice a week | 7,111 (18.8) | 4,097 (10.8) | 11,208 (14.8) | |
| 4 times a week | 3,176 (8.4) | 1,382 (3.7) | 4,558 (6.0) | |
| 5 times a week or more | 7,596 (20.1) | 2,215 (5.9) | 9,811 (13.0) | |
| Frequency of moderate PA Number (%) | No moderate PA | 7,383 (19.5) | 13,794 (36.5) | 21,177 (28.0) |
| Once a week | 7,276 (19.2) | 8,776 (23.2) | 16,052 (21.2) | |
| Twice a week | 7,752 (20.5) | 6,851 (18.1) | 14,603 (19.3) | |
| Thrice a week | 6,523 (17.2) | 4,500 (11.9) | 11,023 (14.6) | |
| 4 times a week | 2,565 (6.8) | 1,484 (3.9) | 4,049 (5.4) | |
| 5 times a week or more | 6,374 (16.8) | 2,365 (6.3) | 8,739 (11.6) | |
| Frequency of muscular strength exercises Number (%) | No muscular strength exercises | 13,608 (35.9) | 25,283 (66.9) | 38,891 (51.4) |
| Once a week | 7,483 (19.8) | 6,014 (15.9) | 13,497 (17.8) | |
| Twice a week | 5,481 (14.5) | 2,909 (7.7) | 8,390 (11.1) | |
| Thrice a week | 4,542 (12.0) | 1,649 (4.4) | 6,191 (8.2) | |
| 4 times a week | 1,781 (4.7) | 628 (1.7) | 2,409 (3.2) | |
| 5 times a week or more | 4,978 (13.1) | 1,287 (3.4) | 6,265 (8.3) | |
| Level of mental stress Number (%) | Very high | 3,619 (9.6) | 5,472 (14.5) | 9,091 (12.0) |
| High | 9,928 (26.2) | 13,098 (34.7) | 23,026 (30.4) | |
| Average | 16,649 (44.0) | 14,833 (39.3) | 31,482 (41.6) | |
| Low | 6,468 (17.1) | 3,968 (10.5) | 10,436 (13.8) | |
| Very low | 1,209 (3.2) | 399 (1.1) | 1,608 (2.1) | |
Data are expressed as mean ± standard deviation or number (%)
PA; physical activity