Postural control strategies in individuals with and without chronic ankle instability during the reach phase of the posteromedial direction of the star excursion balance test.

OBJECTIVE

To compare center of mass (COM) and center of pressure (COP) displacement, joint angles, and muscle activity for the ankle, knee, and hip during the posteromedial (PM) reach direction of the Star Excursion Balance Test between individuals with chronic ankle instability (CAI) and healthy individuals.

DESIGN

Cross-sectional Study.

SETTING

Biomechanics laboratory.

PARTICIPANTS

Fifteen individuals with CAI (age: 20.0 ± 1.2 y) and 20 healthy individuals (age: 20.6 ± 0.8 y).

MAIN OUTCOME MEASURES: The maximum reach distance (MRD). The COM and COP displacement, and ankle, knee, and hip joint angles of the stance limb during the PM reach task measured via a 3D motion analysis system. Electromyography (EMG) was also recorded during the task from the tibialis anterior (TA), soleus, peroneus longus, vastus medialis (VM), biceps femoris, and gluteus medius muscles.

RESULTS

MRD of the CAI group was shorter than the healthy group (P = 0.005). The CAI group showed higher COM positioning (P = 0.007), less knee flexion (P = 0.009), and lower muscle activity in TA (P = 0.04), and VM (P = 0.007) during performance of the PM reach as compared to the healthy group.

CONCLUSIONS

These findings suggest that individuals with CAI demonstrate altered postural control strategies during PM reach performance, likely contributing to a shorter MRD.