This document discusses, among other things, systems and methods for managing pain of a subject. A system may include one or more sensors configured to sense a signal indicative of muscle electrical or mechanical activity at a specific body location. The muscle electrical or mechanical activity signal may include an electromyography or a mechanical contraction signal. A pain analyzer circuit may extract from the sensed signal one or more signal metrics indicative of muscle tension, and generate a pain score using the signal metrics. The pain score may be output to a user or a process. The system may include a neurostimulator that can adaptively control the delivery of pain therapy by automatically adjusting stimulation parameters based on the pain score.