Abstract
The stiffness of the elbow flexor muscle (biceps brachii) was measured in male and female long distance runners with the static loading method using a newly devised simple apparatus with different joint angles. The stiffness of the biceps was the greatest when the elbow joint was completely extended. Muscle stiffness decreased with increased elbow flexion. Muscle stiffness was the least at an elbow joint angle of 60°in both males and females. There were significant differences in muscle stiffness at joint angles between 0°and 30° (p<0.01), between 0°and 90° (p<0.01) and between 0°and 60° (p<0.001) in male runners, and between 0°and 60° (p<0.01) in female runners. In many athletes relaxed muscles are necessary for high performance. At flexion angles of 60°to 90°the biceps muscle was softer than at other angles. At these angles the biceps shows almost body length in which the muscle generates the maximal active tension. These results support the correlation between performance and muscle softness. Furthermore, these results suggest that the simple static loading device used in this study provides information for the quantitative analysis of muscle stiffness in humans.
