Biomechanical Effects of a 6-Week Change-of-Direction Technique Modification Intervention on Anterior Cruciate Ligament Injury Risk.

ABSTRACT: Dos'Santos, T, Thomas, C, Comfort, P, and Jones, PA. Biomechanical effects of a 6-week change-of-direction technique modification intervention on anterior cruciate ligament injury risk. J Strength Cond Res XX(X): 000-000, 2021-The aim of this study was to evaluate the biomechanical effects of a 6-week change-of-direction (COD) technique modification intervention on anterior cruciate ligament (ACL) injury risk (i.e., multiplanar knee joint loads) during 45° (CUT45) and 90° (CUT90) side-step cutting. A nonrandomized, controlled 6-week intervention study was administrated. Fifteen male multidirectional sport athletes formed the intervention group (IG) who participated in two 30-minute COD technique modification sessions per week, whereas 12 male multidirectional sport athletes formed the control group and continued their normal training. Subjects performed 6 trials of the CUT45 and CUT90 task whereby pre-to-post intervention changes in lower-limb and trunk kinetics and kinematics were evaluated using three-dimensional motion and ground reaction force analysis. Two-way mixed analyses of variance revealed no significant interaction effects of group for CUT45 and CUT90 multiplanar knee joint loads (p ≥ 0.116, η2 ≤ 0.096); however, considerable individual variation was observed (positive (n = 5-8) and negative responders (n = 7-8)). Based on IG group means, COD technique modification resulted in no meaningful reductions in multiplanar knee joint loads. However, individually, considerable variation was observed, with "higher-risk" subjects generally responding positively, and subjects initially considered "low-risk" tending to increase their multiplanar knee joint loads, albeit to magnitudes not considered hazardous or "high-risk." Change-of-direction technique modification training is a simple, effective training method, requiring minimal equipment that can reduce knee joint loads and potential ACL injury risk in "higher-risk" subjects without compromising performance.