2016 年 7 巻 1 号 p. 7-14
The purpose of this study is to examine the effect of knee bracing on static and dynamic balance (postural stability).
Two knee braces were examined: soft type (A, “Short Runner Airmesh”) and hard type (B, “Townsend-Rebel TM5”). For thirteen collegiate American football players, three conditions – no bracing (Group N), attached brace A (Group A), and attached brace B (Group B) – were set. All subjects performed three tests: a) single-leg standing with eyes closed to measure static balance, b) forward single-leg drop jump with eyes open, and c) lateral single-leg drop jump with eyes open to measure their dynamic balance, by using Zebris PDM-S system. We measured two items: 1. total track length (mm) of center of pressure (COP) and 2. confidence ellipse area (mm2). The results showed a significant difference between the groups in COP total track length of lateral single-leg drop jump with eyes open, with Group N: 539.2±74.4, Group A: 552.0±66.5, and Group B: 566.2±54.7 (mm).
Consequently, dynamic balance was shown to decrease when a knee brace was worn, and a hard type reduced dynamic balance more than a soft type. We suspected that bilateral uprights contacted the knee joint hindered the joint proprioception, during controlling the balance of the side movement after landing. Moreover, many compression and contact parts against the knee joint due to the hard shell and rigid straps of a hard type caused to reduce the dynamic postural stability.
