Influence of choking in Judo on vision in well-trained Judoka: an explorative field study.

The present study was designed to investigate the effects of a cross-choking-technique commonly used in Judo on visual acuity. In 156 Judokas, experienced in competition, visual acuity was examined before and after choking (Juji-Jime). The average age of the 46 female and 110 male subjects was 22.8 years (standard deviation 10.5 years). In all examined grades of distance (infinite, 0.55 m and 0.4 m), eye tests showed an improvement of visual acuity after choking on a highly significant scale. In quantitative terms, vision the far sight range was optimized more clearly than in the close ranges. The following mechanisms are discussed as possible causes of the present results: an increase of blinking frequency induced by stress, an optimized tear film covering the cornea, a stenopaeic gap induced by improved blinking, pupillomotor alterations and an improved cerebral processing of visual signals and information. From an evolutionary-biologic perspective, the benefit of this psychophysiological mechanism might consist in an improvement of visual acuity in moments of danger, approaching from a distance and, thus, better chances of survival.