Abstract
The maximal dorsiflexion of the ankle is considered a stable position knownas the closed-pack position due to bony conformity. However, no in vivo study has examined stability of the ankle in maximal dorsiflexion. We defined the ankle allowing for passive internal rotation in maximal dorsiflexion as “the ankle with unstable mortise (AUM)". This study investigated the prevalence of AUM and examined the effectiveness of ankle internal rotation exercise on improvement of AUM. Seventy-six young athletes were randomly allocated to an intervention group or a control group. AUM and sports performances in all subjects were evaluated before and after intervention. The prevalence of AUM was very high in young athletes. The intervention tended to improve AUM, but not sports performances. It was suggested that the prevalence of AUM is very high in young athletes and ankle internal rotation exercise may improve AUM.
