The association between weekly hours of physical activity and mental health: A three-year follow-up study of 15–16-year-old students in the city of Oslo, Norway

Table 2 Strengths and Difficulties Questionnaire (SDQ) mean score at age 15–16 years (baseline) and at age 18–19 years (follow-up) in boys and girls in Oslo (2001–2004).

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

*General Linear Model Repeated Measure showed a statistical interaction between time and gender (p < 0.001)
**Paired t-test
***Un-paired t-test

ISSN: 1471-2458