We have done the electromyographic observations of dorsal muscles in lumbago Patients. These observations have been done at maximum constraction on shore and crawl swimming in water. And we have opened lumbago swimming school in National Institute of Fitness and Sports in Kanoya for 4 years. We have educated usual lumbago patients (10 male, 11 female, 46.3 years old) and athlete lumbago patients (11 male, 20.1 years old) in this school. This school was composed of fundamental lecture for lumbago and under-water exercise. Under-water exercise had contained joint mobilization, soft tissue stretching, muscle strengthening and aerobic exercise. We have gotten some conclusions as below.
　1. In the electromyographic observations of dorsal muscles in lumbago patients on shore, they showed weakness and right - left unbalance. In addition they showed large ratio of high frequency area (100 ~ 250 Hz) significantly (P< 0.05) when compared with the electro-myographic results in normal men.
　2. In the electromyographic observations of dorsal muscles in lumbago patients during crawl stroke swimming, they improved the discharge dose and recovered right-left balance. In addition they showed usual ratio of high freguency area (100~250 Hz) when compared with the electromyograhic results in normal men.
　3. In the results of swimming school for lumbago patients, the values of knee flection power, spine functional test and lumbago treatment judgement score (Japanese Orthopaedic Association score) were improved significantly (P< 0.01) in both usual and athlete lumbago group. The values of Vo₂max, vital capacity and dorsal muscle power were improved significantly (P< 0.05) in only usual lumbago group.
We have concluded that swimming exercise has excellent effects for lumbago patients from the electromyographic findings and swimming back school results.

DESCENTE SPORTS SCIENCE Vol.13/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE