Background Sumo has long been a traditional sport in Japan, and recently is becoming a popular sport that is rapidly attracting enthusiasts abroad. With the aim of having the sport included in the Olympics, World Women Sumo Championships as well as World Sumo Championship have also been held since 1999. In October 2010, these Championships will be held in Poland.

Objectives The purpose of this study was to examine the radiological changes in the lumbar spine in freshman collegiate and high school sumo wrestlers and the relationship between the radiological changes and the lumbar spine symptoms.

Design Epidemiology.

Setting High school league and elite division.

Participants We examined 78 freshman collegiate and 16 high school sumo wrestlers who belonged to the Japanese Sumo Federation. They were high level players.

Interventions They underwent routine radiographic examination of their lumbar spine and questionnaire of their lumbar symptoms as a medical check.

Results Their mean height was 175.3 cm, weight was 113.8 kg, body mass index (BMI) was 37.0 kg/m2, and sumo career was 7.9 years in college. High school sumo wrestlers were significantly smaller than collegiate ones in weight, BMI and sumo career. 10 high school wrestlers (62.5%) and 43 collegiate ones (55.1%) had some lumbar symptoms. Seven high school wrestlers (43.8%) and 25 collegiate ones (32.1%) had deformities of lumbar spine. No significant difference existed during two groups in the above phenomena. However, the occurrence rate of spondylolysis in high school wrestlers (31.3%) was significantly larger than collegiate ones (11.5%). The correlation between spondylolysis and lumbar symptoms was significant. Therefore, it may be indicated that sumo wrestlers give up to continue this sport because of symptomatic spondylolysis.

Conclusion Early detection and treatment of spondylolysis is needed because it may decrease sports performance in sumo wrestlers.