Table 4.

Characteristics of the children in the physical activity group

		Weekly physical activitiesc
Item			High		Low
			Mean	SE	mean	SE	P-valuea
Age			8.95	0.027	9.2	0.031
Height			134.0	0.18	135.2	0.21	< 0.001
Weight			29.9	0.13	31.2	0.16	< 0.001
		N	N	%	n	%	P-valueb
Gender	Boys	3619	2161	59.7	1458	40.3	< 0.001
	Girls	3429	1605	46.8	1824	53.2
School year	1	1393	756	54.3	637	45.7	< 0.001
	2	1283	723	56.4	560	43.6
	3	1218	705	57.9	513	42.1
	4	1180	670	56.8	510	43.2
	5	1111	560	50.4	551	49.6
	6	863	352	40.8	511	59.2

^aWilcoxon. ^bChi-square test

^cThe median number of physical activities per week was divided into two