Balance ability was evaluated through the balance test
using the Libra board (Easytech, Prato, Italy). This
instrument (42 9 42 cm, weight 2.7 kg) consists of a
balancing board with a wide antislip area. A Libra board is
connected to a personal computer, and balance ability can
be assessed with appropriate software (Libra software,
version 2.2). The wide support area of the Libra board
consists of three interchangeable plugs, making it possible
to have different degrees of structural difficulty
(40 cm = high; 24 cm = moderate; 12 cm = easy). Subjects were asked to fixate on a point on the wall, in the eye
plane, at a distance of 3 m. A moderate degree of difficulty
was set, with the board plug placed at 24 cm.