Effects of the Suboccipital Muscle Inhibition Technique on the Range of Motion of the Ankle Joint and Balance According to Its Application Duration: A Randomized Controlled Trial

This study aimed to investigate the effects of suboccipital muscle inhibition technique (SMIT) on active range of motion (AROM) of the ankle joint, lunge angle (LA), and balance in healthy adults, according to the duration of its application. A total of 80 participants were randomly allocated to the 4-min suboccipital muscle inhibition (SMI) group (SMI_4M, n = 20), 8-min SMI group (n = 20), 4-min sham-SMI (SSMI) group (n = 20), and 8-min SSMI group (n = 20). Accordingly, the SMIT and sham SMIT were applied for 4 min or 8 min in the respective groups. AROM of dorsiflexion and LA were assessed, and a single leg balance test (SLBT) was performed before and after the intervention. AROM (4 min, p < 0.001; 8 min, p < 0.001), LA (4 min, p < 0.001; 8 min, p < 0.001), and SLBT (4 min, p < 0.001; 8 min, p < 0.001) significantly improved after SMI application. Compared with the SSMI group, the SMI group showed a significant increase in AROM (p < 0.001), LA (p < 0.001), and SLBT (p < 0.001). Except for SLBT (p = 0.016), there were no significant interactions between intervention and application duration. The results suggest that the SMIT, at durations of both 4 and 8 min, could be effective tools for improving AROM, LA, and balance.