Ankle Coordination in Chronic Ankle Instability, Coper, and Control Groups in Running

Coordination and coordination variability have been used as a measure of the function and flexibility of the sensorimotor system during running. Chronic ankle instability (CAI) is associated with altered sensorimotor system function compared with individuals without CAI. Copers may have adopted protective sensorimotor adaptations to prevent repeated ankle sprains; however, their coordination strategies between the foot and shank have not been investigated. We compared joint coupling angles and coordination variability using vector coding between individuals with CAI, copers, and controls.

Seventeen individuals with CAI, 17 copers, and 17 controls ran on the treadmill at a fixed speed of 2.68 m·s. A 10-s trial of continuous data was collected for kinematic analysis. The first five complete strides were used for vector coding. Means of the vector coding angles and variability of frontal plane ankle motion/transverse plane tibia motion and sagittal plane ankle motion/transverse plane tibia motion (SAK/TT) were calculated. A curve analysis with 90% confidence intervals was performed to detect differences between groups.

Controls demonstrated greater angles of SAK/TT than individuals with CAI and greater angles of FAK/TT than copers during the second half of stance. In general, the control group demonstrated greater variability than individuals with CAI and copers, and copers demonstrated greater variability than individuals with CAI.

Chronic ankle instability and copers demonstrated different coordination strategies than controls during loading and propulsion, adding evidence to support a sensorimotor deficit or compensation. Further, limited variability in people with history of CAI during impact and midstance may contribute to higher risk of reinjury, and be an important area for further research.