Compensatory Kinetics During the Side-Hop Test in Individuals With Chronic Ankle Instability

Context: Individuals with chronic ankle instability (CAI) exhibit altered movement strategies during side-cutting tasks. However, no researchers have assessed how altered movement strategies affect cutting performance. Objective: To investigate compensatory strategies in the side hop test (SHT), with a focus on the entire lower extremity, among individuals with CAI. Design: Cross-sectional study. Setting: Laboratory. Patients or Other Participants: A total of 40 male soccer players comprising a CAI group (n = 20; age = 20.35 +/- 1.15 years, height = 173.95 +/- 6.07 cm, mass = 68.09 +/- 6.73 kg) and a control group (n = 20; age = 20.45 +/- 1.50 years, height = 172.39 +/- 4.39 cm, mass = 67.16 +/- 4.87 kg). Intervention(s): Participants performed 3 successful SHT trials. Main Outcome Measure(s): We calculated SHT time, torque, and torque power in the ankle, knee, and hip joints during the SHT using motion-capture cameras and force plates. Confidence intervals for each group that did not overlap .3 points consecutively in the time series data indicated difference between groups. Results: Compared with the control group, the CAI group showed (1) no delayed SHT time; (2) lower ankle-inversion torque (range = 0.11-0.13 N center dot m/kg) and higher hip-extension (range 0.18-0.72 N center dot m/kg) and-abduction torque (0.26 N center dot m/kg); (3) less concentric power in ankle dorsiflexion-plantar flexion (0.18 W/kg) and inversion-eversion (0.40 W/kg), more concentric power in hip flexion-extension (0.73 W/kg), and more eccentric power in knee varus-valgus (0.27 W/kg). Conclusions: Individuals with CAI were likely to rely on hip joint function to compensate for ankle instability and demon- strated no differences in SHT time compared with the control group. Therefore, the movement strategies of individuals with CAI could differ from those of individuals without CAI, even if SHT time is not different.