Abstract

Context: Few authors have assessed neuromuscular knee-stabilization strategies in individuals with chronic ankle instability (CAI) during functional activities. Objective: To investigate the influence of CAI on neuromuscular characteristics around the knee during a stop-jump task. Design: Case-control study. Setting: Research laboratory. Participants or Other Participants: A total of 19 participants with self-reported unilateral CAI and 19 healthy control participants volunteered for this study. Intervention(s): Participants performed double-legged, vertical stop-jump tasks onto a force plate, and we measured muscle activation around the knee of each limb. Main Outcome Measure(s): We calculated the integrated electromyography for the vastus medialis oblique, vastus lateralis, medial hamstrings, and lateral hamstrings muscles during the 100 ms before and after initial foot contacts with the force plate and normalized by the ensemble peak electromyographic value. Knee sagittal-plane kinematics were also analyzed during a stop-jump task. Results: Compared with control participants, the CAI group demonstrated greater prelanding integrated electromyographic activity of the vastus medialis oblique (CAI = 52.28 ± 11.25%·ms, control = 43.90 ± 10.13%·ms, t36 = 2.41, P = .021, effect size = 0.78, 95% confidence interval = 0.11, 1.43) and less knee-flexion angle at the point of initial foot contact (CAI = 7.81° ± 8.27°, control = 14.09° ± 8.7°, t36 = −2.28, P = .029, effect size = −0.74, 95% confidence interval = −1.38, −0.07) and at 100 ms post–initial foot contact (CAI = 51.36° ± 5.29°, control = 58.66° ± 7.66°, t36 = −3.42, P = .002, effect size = −1.11, 95% confidence interval = −1.77, −0.40). No significant results were noted for the other electromyographic measures. Conclusions: We found altered feed-forward patterns of the vastus medialis oblique and altered postlanding knee sagittal-plane kinematics in the CAI group. These observations may provide insight regarding sensorimotor characteristics that may be associated with CAI. Verf.-Referat