Table 2.
Frequency and percentage (%) of sustained head impacts and results of chi-square analyses between the CONTROL and SHELL groups.
| Variable | Category | CONTROL (n = 547) |
SHELL (n = 421) |
χ2 (df), p Value |
|---|---|---|---|---|
| Helmet Location | Front | 446 (81.5%) | 340 (80.8%) | 6.95 (4), 0.139 |
| Left | 29 (5.3%) | 21 (5.0%) | ||
| Right | 41 (7.5%) | 29 (6.9%) | ||
| Top/Crown | 7 (1.3%) | 16 (3.8%) | ||
| Back | 24 (4.4%) | 15 (3.6%) | ||
| Observed Direction | Front | 458 (84.0%) | 359 (86.1%) | 1.01 (2), 0.605 |
| Left | 38 (6.9%) | 61 (5.5%) | ||
| Right | 49 (8.9%) | 35 (8.4%) | ||
| Starting Stance | 2-point | 82 (15.0%) | 76 (18.1%) | 1.60 (1), 0.206 |
| 3-point | 464 (85.0%) | 345 (81.9%) | ||
| Closing Distance | ≤5 yards | 526 (96.2%) | 397 (94.3%) | 0.86 (1), 0.173 |
| >5 yards | 21 (3.8%) | 24 (5.7%) | ||
| Skill | Blocking | 327 (59.8%) | 65 (15.4%) | 215.30 (2), <0.001 |
| Engaging | 197 (36.0%) | 350 (83.1%) | ||
| Tackling | 23 (4.2%) | 6 (1.5%) | ||
| Striking | Strike | 210 (38.4%) | 261 (61.9%) | 53.06 (1), <0.001 |
| Struck | 337 (61.6%) | 160 (38.0%) | ||
| Guardian Cap Impacts | None | 493 (90.1%) | - | 770.35 (2), <0.001 |
| Yes, 1 Player | 54 (9.9%) | 400 (95.0%) | ||
| Yes, Both Players | - | 21 (5.0%) | ||
| Play-type | Pass | 81 (14.8%) | 96 (22.8%) | 226.30 (4), <0.001 |
| Rush | 103 (18.8%) | 152 (36.1%) | ||
| Individual | 262 (47.9%) | 18 (4.2%) | ||
| Inside Run | 77 (14.1%) | 99 (23.5%) | ||
| 1 vs. 1 | 24 (4.4%) | 56 (13.3%) |
Table 2 Distribution of head impacts between groups were comparable for the measured location in addition to observed direction, starting stance, and closing distance categories.