Table 1 Descriptive characteristics of the studied adolescents (n=359)

Age (y)

14.8 ± 1.2

14.8 ± 1.2

14.8 ± 1.1

Sexual maturation

(I/II/III/IV/V) (%)

(0/2/6/13/79)

(0/3/9/20/68)

(0/1/4/6/89)*

Body mass (Kg)

58.3 ± 13.1

62.2 ± 15.3

54.6 ± 9.1*

Height (cm)

164.6 ± 10.9

168.5 ± 12.2

160.4 ± 7.2*

Whole body lean mass (Kg)

40.5 ± 8.5

45.6 ± 8.5

35.5 ± 4.7*

Whole body fat mass (Kg)

14.8 ± 6.1

13.3 ± 6.5

16.4 ± 5.3*

Whole body BMC ^a (g)

1999.34 ± 421.73

2127.21 ± 473.35

1873.61 ± 318.34*

Lumbar spine BMC ^a (g)

51.15 ± 12.84

52.13 ± 14.87

50.16 ± 10.38

Femoral neck BMC ^a (g)

4.24 ± 0.89

4.63 ± 0.97

3.85 ± 0.61*

MVPA ^b (minutes/day)

58.8 ± 24.1

65.7 ± 24.8

49.9 ± 20.4*

TV viewing (minutes/day)

107.1 (62.1-150)

107.1 (57.8-139.3)

107.1 (75–167.1)

Use of computer games (minutes/day)

23.6 (0–60.)

36.4 (12.8-77.1)

7.5 (0–36.4)*

Use of console games (minutes/day)

4.3 (0–36.4)

25.7 (4.3-57.8)

0 (0–4.3)*

Use of internet for non-study (minutes/day)

45 (15–92.1)

36.4 (10.7-75)

57.8 (23.6-107.1)*

Use of internet for study (minutes/day)

15 (9.1-36.4)

15 (0–32.1)

15 (10-7-45)*

Time of study (minutes/day)

90 (36.4-132.9)

75 (23.6-120)

90 (45–150)*

Total sedentary time (minutes/day)

331.1 (242.1-460.2)

327.9 (241.1-457.5)

340.7 (242.1-473.6)