1981 年 25 巻 4 号 p. 281-288
The purpose of this study is to clarify the relationship between the shoulder adduction strength and the stationary enduring time in the straight body cross on rings. Eight-five experienced collegiate gymnasts were assigned to the measurement of two types of maximal shoulder adduction strength (isometric and eccentric) and the stationary holding time in the straight body cross on rings. Electromyogram (EMG) was also recorded on eight out of these subjects during the measurements of the shoulder adduction strength and the performance of straight body cross on rings. The results were as follows: 1) The isometric and eccentric strengths per body weight of the successful performers of the straight body cross (N=43) were above 0.70 and 0.85, respectively. These two figures were significantly greater than those of the unsuccessful performers (N=42). 2) The ratio of the eccentric shoulder-adductive strength per body weight to the isometric one was significantly higher in the successful performers than that of the unsuccessful performers. But there was a significant positive correlation between these two types of strength. 3) When the successful performers of the straight body cross were further divided into two groups of those who use the straight body cross in competition (N=23) and those who do not use this stunt (N=20) no significant differences were found between these two groups in the isometric and eccentric strengths per body weight and also in the ratio of the latter to the former. But the stationary enduring time of the straight body cross of those who use this stunt in competitions was significantly longer than that of non-using group. 4) There was high correlation between shoulder adduction strength per body weight and stationary enduring time in straight body cross on rings; And the regression line of the group using the straight body cross in competitions was different from that of the non-using group. 5) The pattern of electric discharge from the muscle at the shoulder adduction was similar to that of the stationary holding position on rings. But the amount of electric discharge of the latter was greater than that of the former.