Quantification of gait characteristics and muscle activation in patients with chronic ankle instability during walking on sand: A randomized crossover trial.

BACKGROUND

Limited evidence exists regarding the movement control patterns of individuals with chronic ankle instability (CAI) during sand walking. This study aimed to analyze gait characteristics and muscle activation in patients with CAI while walking on sand.

METHODS

This study recruited 30 participants, including 15 patients with CAI and 15 healthy controls. Patients with CAI were selected based on having experienced at least a lateral ankle sprain within 12 months before recruitment. They also had to scoring ≤ 27 on the Cumberland ankle instability tool. This study was conducted using a randomized crossover trial. All participants were asked to walk three times each at their natural speed on both sand and paving blocks for a distance of 50m. There was at least a week between each trial.

RESULTS

The lower limb gait kinematics, spatiotemporal, and muscle activity parameters while walking on sand and paving blocks were compared between both groups. Significant differences in knee angle were observed between 60.83% and 75.34% of the gait cycle during walking on sand in the patients with CAI. Regarding spatiotemporal parameters, cadence (P = .001) and stride length (P = .049) showed significant differences as the main effect. In the CAI group, the recruitment threshold for the peroneus longus muscle was significantly lower during walking on sand than on paving blocks (P < .001). In contrast, the motor unit action potential (MUAP) was significantly higher (P < .001). For the tibialis anterior muscle, the recruitment threshold and number of motor units were significantly lower during walking on sand than on paving blocks (P = .006 and P = .003, respectively), and the MUAP was significantly higher (P < .001). During walking on sand, patients with CAI exhibited increased knee flexion angle, stride length, and MUAP, along with decreased cadence and recruitment thresholds.

CONCLUSION

These results suggest that sand can influence gait characteristics and muscle activation in patients with CAI. Our findings indicate that gait characteristics and muscle activation changes in patients with CAI could potentially benefit CAI rehabilitation.