Differential treatment responses on somatic pain indicators after EMG biofeedback training in back pain patients.

Treatment responses to relaxation-oriented EMG biofeedback (EMGBF) in patients categorized in terms of the Back Pain Classification Scale (BPCS) were examined. It was demonstrated that the previously observed effectiveness of EMGBF training became even more pronounced when the patients were divided into "organic" and "functional" subtypes according to the BPCS. The "organic" group showed the greatest degree of improvement. The mechanism of treatment effectiveness is discussed with reference to physiological changes, i.e., restoration of appropriate back muscle strength and back muscle functioning.