The work presents the neurophysiological validation of simultaneous intrinsic and reflexive joint impedance estimates. The simultaneous intrinsic and reflexive joint impedance parameters are estimated using an online parallel-cascade (PC) algorithm. The neurophysiological validation is performed by investigating the linear association of the PC algorithm estimations with EMG. The work was performed and presented within a clinical/rehabilitation context to support the use of the PC technology for people with joint hyper-resistance. In short, the main goal of this paper is to perform a group-level neurophysiological validation of the PC system identification technique to support its clinical application.