The present disclosure provides a testing device for testing a subject's susceptibility to injury. The testing device may comprise a base for supporting a frame and an actuator that is supported by the frame, the actuator is configured to impart a physical perturbation upon or proximal a target body-part of the subject. The testing device may also comprise a movement-sensing component for attaching to the tested body-part, the movement-sensing component for detecting the subject's movement after the physical perturbation of the target body-part. The present disclosure also provides a system that includes the testing device and a processor for operating software applications for monitoring and tracking the subject's test data. The present disclosure also provides a method for operating the testing device and system. The present disclosure also provides an apparatus for modifying the stability of a joint of a subject.
