Abstract
Single-leg standing is performed in various daily activities such as wearing and removing trousers, stepping into and out of a bathtub, and ascending and descending stairs. Therefore the acquisition of stable and safe single-leg standing is crucial for independent living. Watanabe et al. (Journal of Kansai Physical Therapy, Vol. 9) have reported the importance of the trunk and hip muscle activities of the legs both on and off the ground in the single-leg standing position. Single-leg standing also requires maintenance of the center of pressure (COP) by the foot on the ground. To achieve this condition, the functions of the trunk and hip as well as the functional activity of the foot on the ground have important roles, including the ability to keep COP in the same place, and the ability to flexibly shift COP with the foot on the ground. In addition to the trunk and hip muscle activities, these abilities are attained when the functional muscle activity of the foot activates the medial and lateral longitudinal and transverse arches. This paper describes the assessment methods of the lateral longitudinal arch and the function of the abductor digiti minimi muscle of the foot in supporting the lateral longitudinal arch.
