Ankle dorsiflexion range of motion is associated with compression stiffness of gastrocnemius and soleus muscles, foot structures, and hallux extension range of motion

Abstract

Background This study aimed to identify factors affecting ankle dorsiflexion range of motion (DROM) under non-weightbearing (knee extended and flexed) and weightbearing conditions. Methods Thirty-four healthy participants were assessed using 3D foot scanner, Foot Posture Index (FPI-6), hallux extension ROM, anterior ankle displacement, and muscle stiffness (gastrocnemius and soleus) via ultrasonic shear wave elastography and myotonometer. Results Multiple regression showed that DROM was associated with arch height index and lateral gastrocnemius compression stiffness via myotonometer under non-weightbearing with the knee extended; with FPI-6, hallux extension ROM, and lateral gastrocnemius compression stiffness under non-weightbearing with the knee flexed; and with FPI-6 and soleus compression stiffness under weightbearing conditions (adjusted R ² = 0.34–0.46, P < 0.001). Conclusions This study indicates that ankle DROM is associated with foot structure, hallux ROM, and compression stiffness of gastrocnemius and soleus muscles. Specific contributing factors were identified for DROM under non-weightbearing and weightbearing conditions.