Can isokinetic muscle strength training with hip abduction and adduction improve muscle strength, balance, and gait in patients with functional ankle instability? A randomized controlled trial.

Background: Previous studies have confirmed that patients with functional ankle instability (FAI) have inadequate hip abductor muscle strength. Muscle strength training is a commonly used intervention in people with FAI. The effects investigated by previous studies have shown conflicting results. However, whether hip adduction and abduction isokinetic muscle strength training can improve muscle strength, balance, and gait in patients with FAI remains unclear.

Objective: The aim of this study was to observe whether muscle strength, balance, Cumberland Ankle Instability Tool (CAIT) score, plantar pressure, and gait can be improved in patients with FAI via isokinetic muscle strength training of the peri-ankle muscle groups combined with hip abduction and adductor muscle groups.

Participants: FAI (n=70).

Interventions: The 70 FAI patients were randomly divided into an ankle isokinetic strength training (AIT) group and a hip isokinetic strength training (HIT) group. The AIT group underwent inversion/eversion and dorsiflexion/plantar flexion isokinetic concentric strength training; the HIT group underwent hip abduction and abduction isokinetic strength training based on ankle isokinetic strength training for six weeks.

Main outcome measures: Before and after training, isokinetic concentric force tests around the ankle and hip adduction and abduction, the Star Excursion Balance Test (SEBT), and plantar pressure and gait assessments were performed.

Results: After 6 weeks of training, significant changes in muscle strength were observed in ankle inversion, eversion, dorsiflexion, plantarflexion, and abduction for both the AIT and HIT groups (Group*Time, P < 0.05). Furthermore, the HIT group exhibited greater increases in muscle strength compared to the AIT group (Group, P < 0.05). Additionally, both groups showed varying degrees of improvement in dynamic balance, CAIT scores, and gait patterns (Time, P < 0.05), with the HIT group demonstrating superior improvement compared to the AIT group (Group, P < 0.05).

Conclusions: Isokinetic strength training through the peri-ankle muscles combined with the hip adductor and abductor muscles was more effective than peri-ankle strength training alone in improving muscle strength, balance, plantar pressure, gait, and self-reported scores in FAI patients.

Trial registration: This study is a randomized controlled clinical trial and has been registered in the China Clinical Trial Registry on 07/04/2022 with registration number ChiCTR2200058341.