Table 2 Mean (SD) values of ground reaction force and joint kinematics for control, previous jumper's knee and recent jumper's knee groups for 30, 50 and 70 cm drop jump.
| Biomechanical variables | CON | PJK | RJK | ||||||
|---|---|---|---|---|---|---|---|---|---|
| 30 cm | 50 cm | 70 cm | 30 cm | 50 cm | 70 cm | 30 cm | 50 cm | 70 cm | |
| VGRF | 2.226 (0.653) | 2.819 (0.882) | 3.070 (0.876) | 2.775 (0.559) | 3.421 (0.569) | 3.795 (0.803) | 2.162 (0.778) | 2.939 (1.123) | 3.148 (1.206) |
| LR VGRF | 13.834 (6.902) | 19.187 (9.543) | 20.609 (9.340) | 22.682 (8.391) | 28.245 (7.634) | 30.871 (9.724) | 13.584 (8.144) | 19.730 (9.901) | 27.369 (12.602) |
| Ankle kinematics | |||||||||
| Flexion td (deg) | –32.387 (4.244) | –36.437 (4.672) | –37.942 (3.646) | –30.626 (9.139) | –34.346 (5.225) | –35.289 (5.109) | –33.044 (5.864) | –40.228 (5.545) | –40.638 (5.677) |
| Flexion (deg) | 6.716 (5.623) | 7.983 (4.046) | 9.695 (4.003) | 3.215 (4.818) | 4.313 (3.868) | 6.172 (5.209) | 1.578 (5.765) | 2.143 (5.347) | –5.307 (15.608) |
| ROM (deg) | 48.687 (5.853) | 55.863 (6.404) | 57.390 (4.784) | 48.775 (5.466) | 55.514 (5.120) | 57.227 (7.304) | 47.458 (5.466) | 53.294 (5.120) | 55.871 (4.766) |
| Angular velocity | 5.498 (0.649) | 6.895 (0.874) | 7.486 (0.922) | 5.925 (0.661) | 7.246 (0.531) | 7.721 (0.940) | 5.416 (0.854) | 6.747 (0.992) | 7.575 (0.777) |
| Knee kinematics | |||||||||
| Flexion td (deg) | –18.303 (6.665) | –19.434 (5.856) | –23.762 (4.887) | –15.692 (6.284) | –16.813 (4.208) | –21.366 (6.254) | –19.231 (6.999) | –18.897 (7.484) | –21.617 (6.519) |
| Flexion (deg) | –46.420 (13.576) | –48.063 (10.521) | –52.700 (9.540) | –36.077 (7.568) | –38.527 (6.283) | –44.230 (9.352) | –44.337 (16.814) | –43.282 (15.181) | –40.349 (9.188) |
| ROM (deg) | 56.756 (11.215) | 67.667 (11.194) | 75.233 (11.097) | 57.640 (7.681) | 67.490 (7.529) | 76.238 (8.798) | 55.354 (17.578) | 62.361 (17.313) | 70.643 (17.708) |
| Angular velocity | –3.404 (0.319) | –3.967 (0.379) | –4.030 (0.254) | –4.119 (0.507) | –4.600 (0.627) | –4.575 (0.714) | –3.121 (0.412) | –3.609 (0.465) | –3.996 (0.387) |
| Hip kinematics | |||||||||
| Flexion td (deg) | 21.547 (6.484) | 22.289 (7.426) | 25.442 (6.540) | 15.491 (6.811) | 15.749 (5.487) | 18.339 (7.937) | 19.323 (10.026) | 20.0589 (10.643) | 19.055 (8.925) |
| Flexion (deg) | 30.823 (10.374) | 31.664 (10.321) | 35.530 (9.337) | 21.667 (8.493) | 23.625 (7.175) | 26.877 (10.016) | 30.649 (14.437) | 31.300 (13.266) | 28.931 (9.368) |
| ROM (deg) | 22.278 (8.781) | 33.616 (12.409) | 40.857 (10.779) | 24.615 (10.265) | 35.066 (10.725) | 44.583 (11.869) | 25.595 (16.261) | 32.674 (18.487) | 40.229 (17.418) |
| Angular velocity | 1.618 (0.368) | 2.158 (0.414) | 2.690 (1.039) | 2.045 (0.618) | 2.482 (0.605) | 2.764 (0.488) | 1.822 (0.554) | 2.182 (0.556) | 2.487 (0.857) |
CON, control; deg, degrees; Flexion td, joint flexion at the time of touch down; Flexion, flexion angle at the time of peak VGRF; LR VGRF, loading rate vertical ground reaction force; PJK, previous jumper's knee; RJK, recent jumper's knee; ROM, range of motion.
Bold font, significant difference compared with CON; italic font, significant difference between PJK and RJK.
VGRF is scaled to m·g (product of body mass and gravity). LR VGRF is scaled to m·g1½ ·l0‐½ (body mass times gravity to the power of 1½ divided by the square root of leg length). Angular velocity is scaled from rad/s to (g/l0)½.