Table 3 The physical education class frequency per week according to the BMI standard.

Group	Category	Boys					Girls
		ß	S.E.	OR	95% CI	P *	ß	S.E.	OR	95% CI	P *
Normal Vs. Underweight	No PE class
	One PE class per week	.155	.073	1.168	1.011-1.349	.035	.029	.060	1.029	.915-1.157	.633
	Two PE classes per week	.483	.057	1.621	1.450-1.812	<.001	.211	.045	1.235	1.131-1.349	<.001
	Over three PE classes per week	1.106	.057	3.023	2.704-3.381	<.001	.806	.045	2.238	2.048-2.446	<.001
Normal Vs. Overweight	No PE class
	One PE class per week	.019	.080	1.019	.872-1.192	.809	-.089	.081	.915	.781-1.072	.271
	Two PE classes per week	.065	.061	1.068	.947-1.204	.285	-.121	.060	.886	.787-.997	.045
	Over three PE classes per week	-.045	.064	.956	.843-1.085	.485	-.258	.066	.772	.679-.878	<.001
Normal Vs. Obesity	No PE class
	One PE class per week	-.034	.078	.967	.830-1.125	.661	.150	.098	1.162	.950-1.407	.125
	Two PE classes per week	-.047	.059	.954	.849-1.072	.425	-.239	.078	.788	.675-.919	.002
	Over three PE classes per week	-.149	.063	.862	.762-.974	.017	-.344	.086	.709	.599-.838	<.001

BMI; Body Mass Index; S.E, Standard Error; OR, Odd Ratio; CI, Confidence Interval; PE, Physical Education. The association of the frequency of PE classes and BMI category, by sex.* tested by logistic regression analysis.