The relationship between knee joint angle and knee flexor and extensor muscle strength

[Purpose] The aim of this study was to determine a relationship between joint angle and muscular strength. In particular, this research investigated the differences in maximum muscular strength and average muscular strength at the knee-joint posture. [Subjects and Methods] The study subjects comprised eight female students in their 20s attending S University in Busan. None of the subjects had functional disabilities or had experienced damage to the lower extremities in terms of measurement of muscular strength. A BIODEX system III model (Biodex medical system, USA) was used to measure joint angles and muscular strength. The axis of the dynamometer was consistent with the axis of motion, and measurements were made at 25° and 67° to examine differences in maximum muscular strength according to joint angle. [Results] The maximum muscular strength both knee-joint extension value, at 67° and flexion value, at 25° the value was larger. The average muscular strength both knee-joint extension value, at 67° and flexion value, at 25° the value was larger. [Conclusion] The results of this study reveal that muscular strength does not reach maximum at particular range angles, such as the knee-joint resting posture angle or the knee-joint middle range angle. Rather, a stretched muscle is stronger than a contracted muscle. Therefore, it is considered that it will be necessary to study the effects of the joint change ratio on muscular strength on the basis of the maximum stretched muscle.