Background
Methods
Baseline study
Follow-up study
Study population
Measures
Mental health
Weekly hours of physical activity in leisure time
Confounding factors
Characteristics at age 15–16 | Boys | Girls | |||
---|---|---|---|---|---|
n = 1085* | % |
n = 1348* | % |
p, gender
| |
Invitation group
|
0.489
| ||||
In school |
913
| 84.1 |
1148
| 85.2 | |
By mail |
172
| 15.9 |
200
| 14.8 | |
Ethnic background
|
0.099
| ||||
Ethnic Norwegian |
879
| 81.5 |
1057
| 78.8 | |
Ethnic minority |
200
| 18.5 |
285
| 21.2 | |
Family economic status
|
0.047
| ||||
Very bad/Bad |
285
| 26.6 |
399
| 30.2 | |
Good |
634
| 59.2 |
771
| 58.3 | |
Very good |
152
| 14.2 |
152
| 11.5 | |
Alcohol use last year
|
0.094
| ||||
2–3 times per week |
42
| 3.9 |
51
| 3.8 | |
Once per week |
137
| 12.9 |
204
| 15.4 | |
2–3 times per month |
233
| 21.9 |
245
| 18.5 | |
Once per month |
94
| 8.8 |
128
| 9.6 | |
A few times |
247
| 23.2 |
342
| 25.8 | |
Not at all |
313
| 29.4 |
357
| 26.9 | |
Smoking
|
<0.001
| ||||
No |
844
| 78.2 |
939
| 70.0 | |
Once in a while |
152
| 14.1 |
232
| 17.3 | |
Yes, daily |
83
| 7.7 |
171
| 12.7 | |
Physical activity
|
<0.001
| ||||
0 hours per week |
82
| 7.6 |
143
| 10.6 | |
1–2 hours per week |
202
| 18.8 |
418
| 31.0 | |
3–4 hours per week |
223
| 20.7 |
361
| 26.8 | |
5–7 hours per week |
263
| 24.4 |
234
| 17.4 | |
8–10 hours per week |
187
| 17.4 |
96
| 7.1 | |
11 hours or more per week |
120
| 11.1 |
60
| 4.5 |
Ethics
Statistical methods
Results
Measure and Time Point | Boys | Girls | |||||||
---|---|---|---|---|---|---|---|---|---|
n
| mean | SD |
p time**
|
n
| mean | SD |
p time**
|
p, gender***
| |
SDQ -Emotional Symptoms |
0.183
|
0.021
| |||||||
baseline
|
1074
| 1.64 | 1.69 |
1340
| 3.38 | 2.27 |
<0.001
| ||
follow up
|
1082
| 1.73 | 1.69 |
1343
| 3.52 | 2.41 |
<0.001
| ||
SDQ – Conduct Problems* |
<0.001
|
<0.001
| |||||||
baseline
|
1076
| 2.07 | 1.67 |
1344
| 1.88 | 1.37 |
0.002
| ||
follow up
|
1083
| 1.67 | 1.39 |
1343
| 1.69 | 1.22 |
0.684
| ||
SDQ – Hyperactivity-Inattention |
0.038
|
<0.001
| |||||||
baseline
|
1074
| 3.22 | 1.93 |
1339
| 3.62 | 1.90 |
<0.001
| ||
follow up
|
1083
| 3.35 | 2.07 |
1344
| 3.88 | 2.11 |
<0.001
| ||
SDQ – Peer Problems* |
0.009
|
0.008
| |||||||
baseline
|
1074
| 1.61 | 1.56 |
1340
| 1.39 | 1.39 |
<0.001
| ||
follow up
|
1083
| 1.50 | 1.54 |
1344
| 1.51 | 1.53 |
0.874
| ||
SDQ -Prosocial Behavior* |
<0.001
|
<0.001
| |||||||
baseline
|
1077
| 6.95 | 1.87 |
1344
| 7.98 | 1.55 |
<0.001
| ||
follow up
|
1083
| 7.69 | 1.71 |
1342
| 8.38 | 1.40 |
<0.001
| ||
SDQ -Total Difficulties* |
0.019
|
0.011
| |||||||
baseline
|
1072
| 8.53 | 4.63 |
1339
| 10.27 | 4.64 |
<0.001
| ||
follow up
|
1082
| 8.25 | 4.51 |
1342
| 10.60 | 5.12 |
<0.001
|
Mental health at age 18–19 years according to physical activity at age 15–16 years
Physical activity per week (age 15–16) | Strengths and Difficulties Questionnaire (age 18–19) | |||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Boys | Girls | |||||||||||||||||||
Crude | Adjusted* | Crude | Adjusted* | |||||||||||||||||
n
| mean | 95%CI | F |
p
|
n
| mean | 95%CI | F |
p
|
n
| mean | 95%CI | F |
p
|
n
| mean | 95%CI | F |
p
| |
SDQ – Emotional Symptoms
| 5.91 |
0.001
| 3.28 |
0.020
| 6.14 |
<0.001
| 0.08 |
0.971
| ||||||||||||
0 hours
|
80
| 2.00 | (1.60–2.40) |
73
| 1.80 | (1.46–2.14) |
141
| 4.05 | (3.64–4.46) |
131
| 3.54 | (3.19–3.89) | ||||||||
1–4 hours
|
424
| 1.96 | (1.78–2.13) |
410
| 1.86 | (1.72–2.01) |
777
| 3.59 | (3.42–3.76) |
750
| 3.48 | (3.34–3.62) | ||||||||
5–7 hours
|
263
| 1.51 | (1.32–1.69) |
254
| 1.56 | (1.38–1.75) |
233
| 3.09 | (2.80–3.37) |
227
| 3.46 | (3.20–3.73) | ||||||||
8 hours or more
|
307
| 1.55 | (1.38–1.73) |
299
| 1.56 | (1.40–1.73) |
156
| 3.18 | (2.80–3.56) |
151
| 3.54 | (3.22–3.87) | ||||||||
SDQ – Conduct Problems
| 2.90 |
0.087
| 1.28 |
0.280
| 1.69 |
0.168
| 1.09 |
0.353
| ||||||||||||
0 hours
|
81
| 1.62 | (1.35–1.89) |
74
| 1.57 | (1.30–1.85) |
141
| 1.89 | (1.69–2.08) |
131
| 1.69 | (1.50–1.88) | ||||||||
1–4 hours
|
424
| 1.71 | (1.57–1.84) |
412
| 1.71 | (1.60–1.83) |
777
| 1.64 | (1.56–1.73) |
753
| 1.63 | (1.55–1.71) | ||||||||
5–7 hours
|
263
| 1.51 | (1.34–1.67) |
253
| 1.58 | (1.43–1.73) |
233
| 1.65 | (1.51–1.79) |
227
| 1.70 | (1.56–1.84) | ||||||||
8 hours or more
|
307
| 1.79 | (1.64–1.95) |
300
| 1.75 | (1.62–1.89 |
156
| 1.72 | (1.53–1.92) |
151
| 1.80 | (1.63–1.97) | ||||||||
SDQ – Hyperactivity- Inattention
| 1.14 |
0.331
| 0.92 |
0.431
| 1.14 |
0.331
| 0.47 |
0.700
| ||||||||||||
0 hours
|
81
| 3.48 | (3.00–3.96) |
74
| 3.31 | (2.89–3.73) |
141
| 4.08 | (3.75–4.41) |
131
| 3.95 | (3.63–4.27) | ||||||||
1–4 hours
|
424
| 3.23 | (3.04–3.42) |
410
| 3.27 | (3.09–3.45) |
778
| 3.78 | (3.63–3.92) |
751
| 3.80 | (3.67–3.93) | ||||||||
5–7 hours
|
263
| 3.32 | (3.08–3.56) |
254
| 3.34 | (3.11–3.57) |
233
| 3.89 | 3.61–4.17) |
227
| 3.90 | (3.66–4.14) | ||||||||
8 hours or more
|
307
| 3.50 | (3.25–3.74) |
299
| 3.50 | (3.29–3.71) |
156
| 3.99 | (3.65–4.33) |
151
| 3.93 | (3.63–4.22) | ||||||||
SDQ – Peer Problems
| 13.3 |
<0.001
| 2.57 |
0.053
| 4.41 |
0.004
| 2.10 |
0.098
| ||||||||||||
0 hours
|
81
| 2.20 | (1.83–2.56) |
74
| 1.79 | (1.48–2.10) |
141
| 1.90 | (1.62–2.18) |
131
| 1.74 | (1.50–1.98) | ||||||||
1–4 hours
|
424
| 1.69 | (1.54–1.84) |
409
| 1.52 | (1.39–1.65) |
777
| 1.49 | (1.38–1.60) |
750
| 1.43 | (1.34–1.53) | ||||||||
5–7 hours
|
263
| 1.21 | (1.04–1.38) |
254
| 1.40 | (1.23–1.56) |
234
| 1.32 | (1.13–1.50) |
227
| 1.47 | (1.29–1.65) | ||||||||
8 hours or more
|
307
| 1.28 | (1.11–1.45) |
300
| 1.35 | (1.20–1.50) |
156
| 1.49 | (1.24–1.73) |
151
| 1.57 | (1.35–1.79) | ||||||||
SDQ – Prosocial Behavior**
| 5.00 |
0.002
| 4.44 |
0.004
| 0.96 |
0.411
| 0.79 |
0.490
| ||||||||||||
0 hours
|
81
| 7.14 | (6.72–7.55) |
74
| 7.40 | (7.04–7.75) |
141
| 8.43 | (8.22–8.65) |
131
| 8.50 | (8.28–8.72) | ||||||||
1–4 hours
|
424
| 7.77 | (7.61–7.94) |
412
| 7.75 | (7.60–7.90) |
778
| 8.33 | (8.23–8.44) |
754
| 8.34 | (8.25–8.43) | ||||||||
5–7 hours
|
263
| 7.53 | (7.32–7.73) |
254
| 7.44 | (7.25–7.63) |
233
| 8.39 | (8.21–8.57) |
227
| 8.42 | (8.25–8.58) | ||||||||
8 hours or more
|
307
| 7.86 | (7.67–8.04) |
300
| 7.86 | (7.68–8.04) |
156
| 8.53 | (8.32–8.74) |
151
| 8.42 | (8.22–8.63) | ||||||||
SDQ – Total Difficulties
| 4.31 |
0.005
| 0.67 |
0.579
| 4.63 |
0.003
| 1.03 |
0.377
| ||||||||||||
0 hours
|
80
| 9.24 | (8.22–10.25) |
73
| 8.32 | (7.43–9.21) |
141
| 11.91 | (11.07–12.76) |
131
| 10.88 | (10.16–11.60) | ||||||||
1–4 hours
|
424
| 8.58 | (8.14–9.02) |
409
| 8.35 | (7.98–8.73) |
776
| 10.51 | (10.15–10.87) |
749
| 10.35 | (10.06–10.65) | ||||||||
5–7 hours
|
263
| 7.54 | (7.01–8.07) |
253
| 7.93 | (7.45–8.40) |
233
| 9.94 | (9.31–10.56) |
227
| 10.56 | (10.02–11.10) | ||||||||
8 hours or more
|
307
| 8.13 | (7.62–8.63) |
299
| 8.15 | (7.72–8.59) |
156
| 10.38 | (9.57–11.20) |
151
| 10.83 | (10.17–11.49) |
Physical activity per week (age 15–16) | Boys | Girls | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Crude | Adjusted** | Crude | Adjusted** | |||||||||
n
| p%*** | OR | 95%Cl | OR | 95%Cl |
n
| p%*** | OR | 95%Cl | OR | 95%Cl | |
0 hours
|
79
| 22.8 | ref. | ref. |
139
| 36.7 | ref. | ref. | ||||
1–4 hours
|
423
| 17.3 | 0.71 | 0.39 – 1.27 | 0.79 | 0.42 – 1.49 |
775
| 28.8 | 0.67 | 0.46 – 0.98 | 0.82 | 0.53 – 1.24 |
5–7 hours
|
262
| 10.3 | 0.39 | 0.20 – 0.75 | 0.51 | 0.25 – 1.04 |
232
| 24.6 | 0.56 | 0.36 – 0.89 | 0.76 | 0.45 – 1.27 |
8 or more hours
|
304
| 17.1 | 0.70 | 0.38 – 1.28 | 0.84 | 0.44 – 1.64 |
155
| 29.7 | 0.73 | 0.45 – 1.19 | 1.05 | 0.61 – 1.81 |