According to the following paper, Injuries in judo: a systematic literature review including suggestions for prevention:
- severe injuries in judo are rare, but when they do occur they are mostly to the brain and spine, mostly occur during throws (as opposed to chokes), and mostly occur due to 'bad falling'
- repeatedly being thrown (as a competitive judoka) does not result in chronic brain injuries
1. Severe brain injuries in Judo
Severe injuries were quite rare and usually affected the brain and spine, whereas chronic injuries typically affected the finger joints, lower back and ears. The most common types of injuries in young judo athletes were contusions/abrasions, fractures and sprains/strains.
The main locations of catastrophic injuries in judo are the brain and the cervical spine.
Kamitani et al35 reported being thrown as the leading injury mechanism of severe head injuries (70%) among judo practitioners, who were mainly younger than 20 years (90%) and practicing judo for less than 3 years (60%).35 The authors assumed lack of falling skills as the prominent cause for severe head injuries among inexperienced judokas.35
Generally, choking in judo induces only subclinical electroencephalographic perturbations,53 but could also lead to brain damage when the ‘choker’ maintains the pressure on the opponent's neck, with blood flow interruption lasting a sufficient time to be harmful to the central nervous system54; in the worst case, this could lead to death.34
In Japan, 26 judokas sustained a spinal cord injury during a 3-year period55 and 19 a neck injury in 8 years.35 Sixty-three per cent of neck injuries occurred while performing a throwing technique, for example, Uchi Mata.35
Note that severe head/spine throwing injuries tend to be the result of single incidents (non-chronic), and that risk of injury is associated with lack of falling skills:
Being thrown seems to be the most frequent situation leading to judo injuries, comprising about 70% (range 42–90%) of cases,3 ,25 including also a few severe and catastrophic injuries34 ,35 (see online supplementary table S5). Additionally, it was indicated that the lack in falling skills is also associated with injuries,36 including acute as well as chronic ones.3 ,34
2. Effect of repeated throwing and choking
Rodriguez et al58 found competitive active judokas having no chronic brain damage induced by the repetitive application of judo-specific throwing and choking techniques.
Citations from review:
3. Epidemiology of injury in Olympic Sports. Oxford, UK: Wiley-Backwell, 2010:161–75.
25. Pediatric martial arts injuries presenting to emergency departments, United States 1990-2003. J Sci Med Sport 2007;10:219–26.
26. Causes and injuries during ippon-seoi-nage throw. Arch Budo 2011;7:17–19.
34. Deaths during the judo classes and activities conducted under the supervision of schools in Japan; from 1983 to 2009. All cases listed and analyzed. Aichi University of Education.
35. Catastrophic head and neck injuries in judo players in Japan from 2003 to 2010. Am J Sports Med 2013;41: 1915–21.
55. Sports-related spinal cord injury in Japan (from the nationwide spinal cord injury registry between 1990 and 1992). Spinal Cord 1996;34:416–21.
58. Long term effects of boxing & judo-choking on brain. Ital J Neurol Sci 1998;19:367–72.