Paradoxical relationship in sensorimotor system: knee joint position sense absolute error and joint stiffness measures

Relationships between joint position sense (JPS) and the sensorimotor characteristics of joint stiffness, time to detect motion, and time to peak torque during a perturbation test have rarely been investigated due to methodological challenges. The purpose of this study was to compare JPS and the sensorimotor characteristics in healthy individuals. A total of 26 healthy subjects completed JPS and a perturbation test on an isokinetic dynamometer. JPS was assessed by comparison of the absolute angle difference between a reference and replicated position. During the perturbation test, the dynamometer moved the knee joint at random intervals. Subjects were asked to react and resist the motion as soon as it was detected. Interestingly, a larger JPS error was significantly correlated with higher joint stiffness (P < 0.05).