Surface EMG topography and pain distribution in pre-chronic back pain patients.

The relationship between surface EMG recordings from paraspinalis recording sites and subjective pain ratings were examined in a group of pre-chronic back pain patients. thirty-eight back pain patients without major orthopedic diagnosis and a pain duration between 2 to 6 months participated in a three week long subjective pain rating. Following the completion of their pain diary, the paraspinal sites were assessed under the "static" postural conditions of sitting and standing using an EMG scanning procedure. Results of the correlational analysis revealed significant and positive relationships between pain and muscle activity in the upper back (Trapezius, T1 paraspinalis sites) and significant but negative relationships between erector spinae activity (L3 paraspinalis site) and pain. When considering etiological factors of pre-chronic back pain, the results support both the organicity model for upper back, as well as the biomechanical model for the lower back.