Table 1 Baseline characteristics of participants

All players

7234

10.8 (1.9)

5082 (70.3)

2152 (29.7)

17.9 (2.9)

3.3 (1.5)

1.9 (1.1)

3.7 (2.1)

Baseball

1748

10.8 (1.8)

1660 (95.0)

88 (5.0)

18.1 (3.1)

3.3 (1.5)

1.5 (1.3)

5.4 (2.2)

Football

1477

10.3 (1.6)

1385 (93.8)

92 (6.2)

17.0 (2.3)

3.1 (1.1)

1.7 (0.9)

3.0 (1.2)

Mini-basketball

797

10.3 (1.5)

434 (54.5)

363 (45.5)

17.0 (2.3)

3.7 (0.9)

2.3 (0.9)

3.4 (1.5)

Volleyball

681

10.8 (1.8)

167 (24.5)

514 (75.5)

17.8 (2.5)

3.4 (1.3)

2.3 (1.4)

4.0 (2.3)

Basketball

680

12.5 (1.6)

371 (54.6)

309 (45.4)

18.5 (2.6)

4.8 (1.7)

2.2 (0.7)

3.6 (1.6)

Kendo

525

11.0 (2.2)

329 (62.7)

196 (37.3)

18.4 (3.2)

3.1 (1.2)

2.0 (0.9)

1.8 (1.2)

Judo

242

11.0 (2.3)

178 (73.6)

64 (26.4)

20.8 (4.8)

2.9 (0.9)

2.1 (0.6)

1.6 (1.1)

Karate

236

9.9 (2.2)

169 (71.6)

67 (28.4)

17.8 (2.9)

2.4 (1.1)

1.9 (0.8)

1.8 (1.5)

Track and field

137

10.3 (1.7)

57 (41.6)

80 (58.4)

17.3 (2.4)

1.7 (0.9)

0.9 (0.9)

2.1 (0.6)

Soft tennis

128

12.1 (1.9)

48 (37.5)

80 (62.5)

18.5 (2.6)

3.7 (1.9)

2.0 (0.8)

4.4 (2.5)

Badminton

123

11. 3 (1.9)

39 (31.7)

84 (68.3)

17.9 (2.5)

2.9 (1.1)

2.1 (0.7)

3.5 (1.7)

Table tennis

94

12.8 (1.9)

37 (39.4)

57 (60.6)

18.7 (2.9)

3.7 (1.9)

2.3 (0.8)

2.9 (1.8)

Handball

41

11.2 (2.3)

24 (58.5)

17 (41.5)

18.3 (2.6)

3.3 (2.0)

2.7 (0.4)

3.3 (0.8)

Swimming

41

9.9 (2.0)

29 (70.7)

12 (29.3)

18.6 (3.1)

2.4 (1.4)

1.2 (0.5)

1.0 (1.0)

Others

284

11 (2.3)

155 (54.6)

129 (45.4)

18.3 (2.9)

2.4 (1.6)

1.7 (0.8)

2.7 (2.0)