# The Effects of Functional Ankle Taping on Postural Stability in Elite Judo Players
###### Abstract  
The purpose of this study was to investigate the effect of ankle taping intervention on postural stability in elite Judo players. A total of twenty-two elite Judo players participated in this study. For biomechanical evaluation of postural stability, all participants performed postural standing tasks including narrow, normal, and wide stance conditions with both taping and non-taping conditions, respectively. Ground reaction forces and the center of pressure (COP) were obtained from the force plate. COP data for 30-s duration were analyzed to assess postural stability by measuring 95% confidence ellipse sway area (COPSWAY), COP velocity (COPVEL), and approximate entropy (ApEn). Significant differences were found in COPSWAY (\(p=0.025\)) and COPVEL (\(p=0.041\)) in the narrow stance, but no differences in normal and wide stance were observed between taping and non-taping conditions. For ApEn in the anteroposterior (AP) direction, significant differences were identified in normal (\(p=0.026\)) and wide (\(p=0.014\)) stances, but in the mediolateral direction there were no significant differences in all stances between taping and non-taping conditions. This study suggests that ankle taping that is purported to increase ankle stability may ironically negatively affect posture maintenance in Judo players. Our study suggests that the purpose of ankle taping should be reconsidered and associated individual objective data should be first analyzed before tape application. Judo; ankle taping; postural stability; nonlinear analysis +
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skills. Recently, it was reported that among the diverse range of potential physical injuries, top-level Judo players most frequently experienced sprain injuries during competitions [6]. Further, Judo is known for high injury rates during competition or training, with ankle sprain and ankle joint injury being the most common injuries (4.98% and 3.98%, respectively) [7]. Particularly, the ankle joint represents the most important joint in Judo as the play requires standing stably when exerting one's own force and bearing the counterpart's exerted force. This means the ankle joint needs to resist forces that are multiple times greater than the weight of the athlete, increasing the risk of an ankle injury [8]. To accommodate for such dynamic and risky characteristics of Judo, most Judo athletes have typically used ankle taping to prevent ankle injury and enhance their performance. Mechanically, taping strengthens the stiffness of the ankle joint to diffuse any overloading on the ankle, thereby reducing the possibility of spraining. This strengthened ankle stiffness helps endure force exerted upon the ankle, ultimately imparting enhanced postural stability [9]. However, a complex relationship between increased ankle stiffness and whole-body balance stability needs to be considered. Perhaps, in addition to the absolute magnitude of the muscle strength exerted from the ankle joint, the degree of freedom of the ankle joint motion (i.e., flexibility) is an important factor that affects dynamic postural stability [10]. This indicates that while taping may positively influence ankle joint's stiffness through strong support, it may also detrimentally affect ankle joint flexibility. In other words, while an increase in stiffness can be considered positively from the perspective of ankle joint stability, it can also reduce ankle joint flexibility from the perspective of whole-body balance. Reduced ankle joint flexibility can negatively affect knee and hip joints that are systematically connected, and ultimately the overall balance ability [11]. Lower extremity joints are systematically connected, and ankle, knee, and hip joints continuously interact to create an optimal bodily balance [12]. This suggests that a particular resistance or a movement may be required in the knee or hip to compensate for reduced ankle joint flexibility [13].