Asymmetry of premotor time in the back muscles of adolescent idiopathic scoliosis.

STUDY DESIGN: In 38 patients with adolescent idiopathic scoliosis (AIS), the correlation between left and right differences in premotor time (D-PMT) of back muscle and clinical findings were analyzed. OBJECTIVE: To investigate the clinical relevance of back muscle D-PMT in AIS. SUMMARY OF BACKGROUND DATA: There have been numerous studies investigating back muscle asymmetry of AIS by EMG, but to date, no studies have measured D-PMT in back muscles. MATERIALS AND METHODS: D-PMT in the back muscles measured in a similar manner as that in the extremity muscles was assessed in 10 nonscoliotic teenaged girls and 38 AIS patients. The correlation between back muscle D-PMT and four factors (age, Risser sign, Cobb angle, and progression of deformity) was investigated. RESULTS: The D-PMT values of back muscle at all levels in the control group were within +/-5 ms, but those in 20 of the 38 AIS patients were more than 5 ms. D-PMT at the lower-end vertebra level was strongly correlated with progression of deformity, but not with age, Risser sign, and Cobb angle. All five patients with D-PMT of more than 10 ms at the lower-end vertebra level had progressive deformity. CONCLUSIONS: D-PMT in back muscle at the lower end vertebra level in AIS correlated closely to the progression of scoliotic deformity, thus suggesting that this phenomenon is associated with the progression in AIS.

A STUDY OF THE PROCESS OF IMPROVEMENT IN ARCHERY / 体力科学

The form and electromyographic pattern of archery shooting were compared between experts and amatures. Using methods are electromyography, photography and X-ray photography.<BR>In the expert group, the shoulder joint of the pushing arm is in neutral position of rotation and the forearm is in supinated position. In the amature group the shoulder joint is in externally rotated and forearm is pronated. The delta muscle provides more powerful abduction of the shoulder in neutral position of rotation.<BR>The different discharge pattern of shoulder girdle muscles between two groups suggests that fixation of the bow is essentially important from release to follow-through.