Active therapies are well-accepted during a rehabilitation process or for the treatment of pain. However they may often cause additional pain that can reduce patient compliance. Mechanisms that control the effect of pain on muscle strength are so far poorly understood. It is of prime importance for the clinician to assess the impact of pain during rehabilitation, and especially the soreness induced by the therapies. Although this problem is recognized, it is often minimized by therapists. If the point of view of the patients is usually pretty close from the one of the therapist, it may differ on some points and this may lead to misunderstandings. In order to adjust the treatment and explanations, it is necessary to have a good assessment of the impact of pain on the lives of the patients. This is compulsory in order to get a better adhesion to the treatment.