Abstract
[Purpose] We investigated the influence ankle dorsiflexion range has on center of foot pressure (COP) during squat action and the ability to perform it. [Subjects and Method] We performed measurements of the ankle dorsiflexion range and center of gravity sway during squat action by 42 healthy adults (average age, 20.1 ± 2.4 years). [Results] Among the 42 subjects there were 27 who could perform the squat action. A significant correlation, r=0.718, was found between the range of ankle dorsiflexion and anteroposterior COP displacement in squatting. The ranges of ankle dorsiflexion for those who could and could not squat were 18.9 ± 4.6° and 9.6 ± 3.5°, respectively, significantly larger for those who could squat. The number of those who could squat became smaller as the range of ankle dorsiflexion got smaller, and at less than 10° none of the subjects (9) could squat. Conversely, at more than 20°, all subjects (13) could perform the action. [Conclusion] The results suggest that when the range of ankle dorsiflexion is insufficient, COP displacement is forced to move posteriorly in squatting, and when the dorsiflexion range is below a set limit, the action becomes impossible.
