Total cohort (12–17 years) | Total cohort divided into age groups | Sub-cohort (12–17 years)a | Baseline versus Follow-Up | Effect Size | ||||||
---|---|---|---|---|---|---|---|---|---|---|
n | n = 419 | 12 years (n = 97) | 13 years (n = 158) | 14 years (n = 91) | 15–17 years (n = 73) | Baseline (n = 286) | Follow-Up (n = 286) | P Value | Cohen’s d | |
Age, years | 418 | 13.9 ± 1.1 | 12.7 ± 0.2 | 13.4 ± 0.3 | 14.5 ± 0.3 | 15.8 ± 0.6 | 13.9 ± 1.2 | 14.9 ± 1.6 | ||
Height, cm | 417 | 163 ± 6.8 | 160 ± 6.4 | 161 ± 6.5 | 165 ± 5.7 | 168 ± 5.8 | 162.5 ± 6.8 | 165.5 ± 5.6 | < 0.001 | 1.07 |
Body mass, kg | 417 | 53 ± 9.0 | 48 ± 7.5 | 51 ± 7.7 | 57 ± 7.6 | 61 ± 7.6 | 53.2 ± 9.0 | 57.8 ± 7.7 | < 0.001 | 1.08 |
Body mass index, kg/m2 | 416 | 20.1 ± 2.5 | 18.8 ± 2.2 | 19.6 ± 2.2 | 20.9 ± 2.4 | 21.8 ± 2.1 | 20.0 ± 2.5 | 21.1 ± 2.4 | < 0.001 | 0.65 |
Menarche, n (%) | 418 | 280 (67) | 35 (36) | 92 (58) | 82 (90) | 71 (97) | 184 (64) | – | – | |
Age at menarche | 416 | 12.4 ± 1.0 | 11.9 ± 0.9 | 12.3 ± 0.9 | 12.7 ± 1.1 | 12.6 ± 1.1 | 12.5 ± 1.1 | – | – | |
Amenorrhea >3 monthsb, n (%) | 412 | 46 (16) | 4 (4) | 17 (11) | 9 (10) | 16 (22) | ||||
Years playing organized football | 417 | 7.0 ± 2.2 | 6.0 ± 1.9 | 6.3 ± 1.8 | 7.5 ± 1.8 | 9.2 ± 1.7 | 7.0 ± 2.2 | – | – | |
Dominant leg, n (%) | 419 | |||||||||
Right | 399 (95) | 95 (98) | 149 (94) | 87 (96) | 68 (93) | 270 (94) | – | – | ||
Left | 17 (4) | 2 (2) | 8 (5) | 4 (4) | 3 (4) | 13 (5) | – | – | ||
Both | 3 (1) | 0 (0) | 1 (1) | 0 (0) | 2 (3) | 3 (1) | – | – | ||
Playing position, n (%) | 414 | 0.466 | ||||||||
Goalkeeper | 34 (8) | 6 (6) | 11 (7) | 9 (10) | 8 (11) | 19 (7) | 21 (7) | |||
Defender | 130 (31) | 37 (38) | 45 (29) | 25 (28) | 23 (32) | 85 (30) | 95 (33) | |||
Midfielder | 168 (41) | 29 (30) | 79 (51) | 36 (40) | 24 (33) | 117 (42) | 109 (38) | |||
Forward | 82 (20) | 25 (26) | 21 (13) | 19 (21) | 17 (24) | 61 (22) | 59 (21) | |||
Football matches/week, n | 419 | 1.5 ± 0.6 | 1.6 ± 0.6 | 1.5 ± 0.6 | 1.4 ± 0.7 | 1.2 ± 0.6 | 1.5 ± 0.6 | 1.4 ± 0.7 | 0.387 | –0.05 |
Football training h/week, n | 419 | 5.0 ± 1.8 | 4.6 ± 1.5 | 5.0 ± 1.6 | 5.0 ± 1.7 | 5.4 ± 2.6 | 5.1 ± 1.9 | 5.1 ± 2.0 | 0.783 | 0.02 |
Other training with football team h/week | 416 | 1.6 ± 1.4 | 1.4 ± 1.2 | 1.5 ± 1.3 | 1.5 ± 1.1 | 2.2 ± 1.8 | 1.7 ± 1.5 | 1.6 ± 1.2 | 0.365 | –0.05 |
Injury prevention training, yes | 419 | 320 (76) | 77 (79) | 121 (77) | 65 (71) | 57 (78) | 223 (78) | 199 (70) | 0.011 | |
Prevention times/week | 400 | 2.5 ± 1.3 | 2.5 ± 1.2 | 2.7 ± 1.2 | 2.2 ± 1.2 | 2.4 ± 1.4 | 2.6 ± 1.3 | 2.9 ± 1.4 | 0.010 | 0.21 |
1–2 times/week | 157 (39) | 36 (37) | 48 (30) | 39 (43) | 34 (47) | 107 (37) | 70 (25) | |||
3–4 times/week | 127 (32) | 32 (33) | 59 (37) | 20 (22) | 17 (23) | 93 (33) | 96 (34) | |||
>4 times/week | 16 (4) | 3 (3) | 7 (4) | 2 (2) | 4 (5) | 11 (4) | 21 (7) | |||
Training with older players in the previous 6 months | 416 | < 0.001 | ||||||||
Every week | 70 (17) | 11 (12) | 16 (10) | 16 (18) | 27 (37) | 52 (18) | 24 (8) | |||
Few times/every month | 28 (7) | 2 (2) | 12 (8) | 4 (4) | 10 (14) | 18 (6) | 37 (13) | |||
Few times previous 6 months | 99 (24) | 26 (27) | 38 (24) | 23 (25) | 12 (16) | 56 (20) | 90 (32) | |||
Never | 219 (53) | 56 (59) | 91 (58) | 48 (53) | 24 (33) | 157 (56) | 133 (47) | |||
Match play with older players in the previous 6 months | 418 | 0.509 | ||||||||
Every week | 33 (8) | 7 (7) | 10 (6) | 8 (9) | 8 (11) | 22 (8) | 19 (7) | |||
Few times/every month | 52 (12) | 7 (7) | 17 (11) | 15 (16) | 13 (18) | 42 (15) | 42 (15) | |||
Few times in the previous 6 months | 124 (30) | 29 (30) | 46 (29) | 25 (27) | 24 (33) | 79 (28) | 92 (32) | |||
Never | 209 (50) | 54 (56) | 84 (54) | 43 (47) | 28 (38) | 142 (50) | 133 (46) | |||
Other training (not football), n (%) | 418 | 135 (32) | 33 (34) | 55 (36) | 23 (25) | 23 (32) | 90 (32) | 85 (30) | 0.615 | |
Other training (not football), h/week | 133 | 2.7 ± 2.0 | 2.5 ± 2.1 | 2.4 ± 1.7 | 2.7 ± 2.2 | 3.5 ± 2.4 | 2.8 ± 2.1 | 2.3 ± 1.5 | 0.002 | −0.45 |