Table 1 Associations of physical activity time categories with potential confounders among urban high-school students in Nanjing, China
| Â | Physical Activity Time (hr/wk) (n, %) | Â | Â | |||
|---|---|---|---|---|---|---|
Characteristics | 0–0.9 | 1–7 | 8–14 | 15 + | χ 2 | p* |
Gender | Â | Â | Â | Â | Â | Â |
   Girls | 286 (54.8) | 590 (56.0) | 243 (49.2) | 145 (38.7) | 36.659 | < 0.001 |
   Boys | 236 (45.2) | 463 (44.0) | 251 (50.8) | 230 (61.3) |  |  |
School Grade | Â | Â | Â | Â | Â | Â |
   7 | 132 (25.3) | 337 (32.0) | 159 (32.2) | 140 (37.3) | 24.219 | < 0.001 |
   8 | 173 (33.1) | 350 (33.2) | 176 (35.6) | 130 (34.7) |  |  |
   9 | 217(41.6) | 366 (34.8) | 159 (32.2) | 105 (28.0) |  |  |
Body Mass Index | Â | Â | Â | Â | Â | Â |
   Non-overweight | 450 (86.2) | 933 (88.6) | 444 (89.9) | 341 (90.9) | 6.588 | 0.361 |
   Overweight | 47 (9.0) | 77 (7.3) | 35 (7.1) | 24 (6.4) |  |  |
   Obesity | 25 (4.8) | 43 (4.1) | 15 (3.0) | 10 (2.7) |  |  |
Father education | Â | Â | Â | Â | Â | Â |
   Junior high school or less | 180 (34.5) | 366 (34.8) | 142 (28.7) | 140 (37.3) | 31.108 | < 0.001 |
   Senior high school | 222 (42.5) | 454 (43.1) | 205 (41.5) | 175 (46.7) |  |  |
   Undergraduate | 102 (19.5) | 195 (18.5) | 125 (25.3) | 42 (11.2) |  |  |
   Graduate | 18 (3.4) | 38 (3.6) | 22 (4.5) | 18 (4.8) |  |  |
Mother education | Â | Â | Â | Â | Â | Â |
   Junior high school or less | 242 (46.4) | 475 (45.1) | 188 (38.1) | 135 (36.0) | 50.965 | < 0.001 |
   Senior high school | 222 (42.5) | 434 (41.2 | 189 (38.3) | 155 (41.3) |  |  |
   Undergraduate | 52 (10.0) | 130 (12.3) | 110 (22.3) | 77 (20.5) |  |  |
   Graduate | 6 (1.1) | 14 (1.3) | 7 (1.4) | 8 (2.1) |  |  |
Family structure | Â | Â | Â | Â | Â | Â |
   Both parents | 480 (92.0) | 925 (87.8) | 413 (83.6) | 320 (85.3) | 24.745 | < 0.001 |
   Single parent | 24 (4.6) | 88 (8.4) | 63 (12.8) | 43 (11.5) |  |  |
   Others | 18 (3.4) | 40 (3.8) | 18 (3.6) | 12 (3.2) |  |  |
Study time†|  |  |  |  |  |  |
   Low | 205 (39.3) | 314 (29.8) | 171 (34.6) | 141 (37.6) | 28.148 | < 0.001 |
   Middle | 141 (27.0) | 351 (33.3) | 175 (35.4) | 132 (35.2) |  |  |
   High | 176 (33.7) | 388 (36.8) | 148 (30.0) | 102 (27.2) |  |  |
Sleep time†|  |  |  |  |  |  |
   Low | 200 (38.3) | 348 (33.0) | 138 (27.9) | 112 (29.9) | 22.317 | 0.001 |
   Middle | 144 (27.6) | 366 (34.8) | 173 (35.0) | 113 (30.1) |  |  |
   High | 178 (34.1) | 339 (32.2) | 183 (37.0) | 150 (40.0) |  |  |
TV time†|  |  |  |  |  |  |
   Low | 148 (28.4) | 338 (32.1) | 170 (34.4) | 150 (40.0) | 41.527 | < 0.001 |
   Middle | 150 (28.7) | 313 (29.7) | 182 (36.8) | 125 (33.3) |  |  |
   High | 224 (42.9) | 402 (38.2) | 142 (28.7) | 100 (26.7) |  |  |
Alcohol consumption | Â | Â | Â | Â | Â | Â |
   Non | 380 (72.8) | 715 (67.9) | 394 (79.8) | 285 (76.0) | 26.589 | < 0.001 |
   Yes | 142 (27.2) | 338 (32.1) | 100 (20.2) | 90 (24.0) |  |  |
Smoking behavior | Â | Â | Â | Â | Â | Â |
   Non | 491 (94.1) | 989 (93.9) | 476 (96.4) | 360 (96.0) | 5.701 | 0.127 |
   Yes | 31 (5.9) | 64 (6.1) | 18 (3.6) | 15 (4.0) |  |  |
Unintentional injuries | Â | Â | Â | Â | Â | Â |
   Non | 348 (66.7) | 666 (63.2) | 311 (63.0) | 224 (59.7) | 4.624 | 0.201 |
   Yes | 174 (33.3) | 387 (36.8) | 183 (37.0) | 151 (40.3) |  |  |
Overall | 522 (21.4) | 1053 (43.1) | 494 (20.2) | 375 (15.3) | - | - |