Yukinori Nakajima, professor - nakajiyu@a.tsukuba-tech.ac.jp
National University Corporation Tsukuba University of Technology, Japan
Member of the Medical Science Committee of the Japanese Federation of the Deaf

In Japan, there are very few studies on the physical functions of deaf athletes. However, in the course of my career of more than 20 years supporting deaf athletes as a coach, I have noted certain issues on the different aspects of their physical functions, and I have involved myself in research, searching for possible solutions. The following two studies are the results of a comparison using an unpaired t-test.
The first point of evaluation involves the balance function of deaf athletes. In Japan, it was noted that several hearing-impaired children have poor balance, but they eventually develop compensatory balance as adults, which is similar to that of normal-hearing individuals.
However, while coaching deaf athletes, we still observed that many of them had poor balance. Therefore, we made a comparison of the balance function between deaf athletes aiming for the Deaflympics Games and young individuals with normal hearing.
Deaf athletes underwent the caloric test for vestibular function. The results showed that 30% of the deaf athletes had abolished or impaired lateral semicircular canal function of the ear.
We also compared the two groups by performing a one-leg standing test and a center-of-gravity sway test. In both tests, there was no difference when the eyes were open; however, when the eyes were closed, the deaf athletes were significantly inferior.
We believe that medical personnel need to understand the poor balance of deaf athletes, as it is a significant factor in the evaluation of concussions during sports activities.
The second point of evaluation is the visual function of hearing-impaired individuals. In coaching deaf athletes, I have observed that they had good eyesight.
Therefore, we evaluated this using the sports vision test, which originated in the United States and consists of eight tests. We tested using Japanese equipment (HT-10, Kowa Co. Ltd.).
The results suggested that they had good overall visual ability, wherein the lateral dynamic visual acuity was particularly good.
Since individuals with impaired hearing often use their eyes laterally to read signs on a daily basis, those who did not engage in regular sports activities were compared with normal-hearing individuals.
The results showed that individuals with impaired hearing had significantly better lateral dynamic visual acuity.
This suggests that the superior lateral dynamic visual acuity of the deaf athletes may not have been cultivated through sports but may be an ability that is acquired in life.
In 2025, Japan will host the 25th Deaflympics Summer Games. We look forward to seeing you!

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