Baseline characteristics of the study sample
| Baseline characteristic | Atom n=41 (4 teams) | PeeWee n=51 (6 teams) | Bantam n=117 (9 teams) | Midget n=115 (9 teams) |
|---|---|---|---|---|
| Age (median with range) (% missing) | 10 (range 9–10) (2.4%) | 12 (range 11–12) (5.9%) | 13.5 (range 13–14) (9.4%) | 16 (range 15–17) (3.5%) |
| Proportion of players in: (95% CI) | ||||
| First year of eligibility | 19/40=47.5% (31.8 to 63.2) | 23/48=47.9% (33.6 to 62.3) | 53/106=50.0% (40.4 to 59.6) | 45/111=40.5% (31.3 to 49.7) |
| Second year of eligibility | 21/40=52.5% (36.8 to 68.2) | 25/48=52.1% (37.7 to 66.4) | 53/106=50.0% (40.4 to 59.6) | 33 /111=29.7% (21.2 to 38.3) |
| Third year of eligibility | n/a | n/a | n/a | 33/111=29.7% (21.2 to 38.3) |
| Height (cm) (mean with 95% CI) (% missing) | 142 (138 to 146) (29.3%) | 152 (150 to 154) (21.6%) | 162 (161 to 163) (17.9%) | 166 (165 to 167) (2.6%) |
| Weight (kg) (mean with 95% CI) (% missing) | 34 (32 to 37) (26.8%) | 44 (41 to 47) (19.6%) | 54 (52 to 56) (21.4%) | 61 (58 to 63) (6.1%) |
| Division: (proportion with 95% CI) | ||||
| B (lowest skill level) | n/a | 16/51=31.4% (18.5 to 44.3) | 52/117=44.4% (35.4 to 53.5) | 22/115=19.2% (11.9 to 26.4) |
| A (middle skill level) | n/a | 35/51=68.6% (55.7 to 81.5) | 65/117=55.6% (46.5 to 64.6) | 52/115=45.2% (36.0 to 54.3) |
| AAA (highest skill level) | n/a | n/a | n/a | 41/115=35.6% (26.8 to 44.5) |
| Position: (proportion with 95% CI) | ||||
| Forward | 17/30=56.7% (38.6 to 74.8) | 30/50=60.0% (46.2 to 73.8) | 65/114=57.0% (47.9 to 66.2) | 63/111=56.8% (47.5 to 66.1) |
| Defence | 9/30=30.0% (13.3 to 46.7) | 16/50=32.0% (18.9 to 45.1) | 40/114=35.1% (26.3 to 43.9) | 34/111=30.6% (22.0 to 39.2) |
| Goalie | 4/30=13.3% (0.9 to 25.8) | 4/50=8.0% (.37.4 to 15.6) | 9/114=7.9% (2.9 to 12.9) | 14/111=12.6% (6.4 to 18.8) |
| Years of girls ice hockey (median with range) (% missing) | 1 (range 0–4) (0.0%) | 2 (range 0–7) (2.0%) | 3 (range 0–8) (3.4%) | 5 (range 0–10) (3.5%) |
| Years of boys ice hockey (median with range) (% missing) | 0 (range 0–4) (17.1%) | 2 (range 0–8) (11.8%) | 2 (range 0–10) (17.1%) | 2 (range 0–10) (13.3%) |
| Total years (median with range) (% missing) | 2 (range 0–5) (0.0%) | 4 (range 0–11) (2.0%) | 5 (range 0–13) (1.7%) | 8 (range 0–15) (2.6%) |
| Previous injury (past 6 weeks) (proportion with 95% CI) | 4/41=9.8% (0.3 to 19.2) | 3/49=6.1% (0.0 to 13.1) | 9/111=8.1% (3.0 to 13.3) | 7/109=6.4% (1.8 to 11.1) |
| Previous injury (past 1 year) (proportion with 95% CI) | 5/38=13.2% (2.2 to 24.1) | 6/47=12.8% (2.9 to 22.7) | 31/110=28.2% (19.6 to 36.7) | 33/110=30.0% (21.3 to 38.7) |
| Previous concussion (proportion with 95% CI) | 1/39=2.6% (0.0 to 7.8) | 1/48=2.1% (0.0 to 6.8) | 15/105=14.3% (7.5 to 21.1) | 38/108=35.2% (26.0 to 44.3) |
n/a, not applicable.