Table 1.

Sample characteristics. High school students from Pelotas to Brazil (n = 1,233)

Variable	Boys		Girls		Total
	N	%	N	%	N	%
Economic level (n = 1,036)
A	44	9.1	38	6.9	82	7.9
B	273	56.6	290	52.3	563	54.4
C	158	32.8	210	37.9	368	35.5
D	7	1.5	16	2.9	23	2.2
Schooling (n = 1,233)
First year	225	39.7	245	36.8	470	38.1
Second year	174	30.7	223	33.5	397	32.2
Third year	168	29.6	198	29.7	366	29.7
Age (n = 1,233)
13/14	73	12.9	83	12.4	156	12.7
15	126	22.2	151	22.7	277	22.5
16	176	31.1	225	33.8	401	32.5
17	143	25.2	148	22.2	291	23.6
18/19	49	8.6	59	8.9	108	8.8
Skin color (n = 1,201)
White	428	78.0	521	79.9	949	79.0
Non-white	121	22.0	131	20.1	252	21.0
Physical activity (n = 1,233)
Inactive	284	50.1	504	75.7	788	63.9
Active	283	49.9	162	24.3	445	36.1
School type (n = 1,233)
Public	484	85.4	587	88.1	1,071	86.9
Private	83	14.6	79	11.9	162	13.1
BMI (kg/m2) (n = 1,191)
Normal	399	72.3	490	76.7	889	74.7
Overweight	111	20.1	124	19.4	235	19.7
Obese	42	7.6	25	3.9	67	5.6
Smoking (n = 1,221)
Former smoker/never smoked	525	93.4	625	94.8	1,150	94.2
Smoker	37	6.6	34	5.2	71	5.8
Low back pain last 30 days (n = 1,233)
No	498	87.8	566	85.0	1,064	86.3
Yes	69	12.2	100	15.0	169	13.7