Normative data on low back mobility and activity levels. Implications for neuromuscular reeducation.

Low back mobility and electromyographic movements were performed in 121 normal subjects, grouped by age and sex. Women tended to show greater ranges of motion for straight leg raising, trunk rotation and lateral bending while vertebral separation (forward flexion) was greater in men. A sex-age interaction was observed only in lateral bending, thus implying that for other mobility measurements, data within the age groupings employed in this study can be combined for men and women. Electromyographic data were integrated and quantified using EMG biofeedback equipment for unilateral or bilateral recordings made primarily from the erector spinae muscle between lumbar 3-4 and lumbar 4-5 levels, three centimeters lateral to the spinous processes. Dynamic (trunk flexion-extension, lateral rotation-standing, stooping) and static (quiet sitting, rotation-sitting) movements were performed over a ten second interval. Data analyses verified previous electromyographic studies by demonstrating the trunk extensor function of the erector spinae and the relatively greater unilateral activity when turning to the opposite direction in the erect posture. EMG silence was seen during full trunk flexion. Noticeable sex-age interaction were observed for all dynamic movements but not for static activities. Therefore, it is suggested that EMG data during dynamic movements in a normal population cannot be grouped for men and women within a specified age distribution. These data represent one series of baselines to which mobility and movement patterns in a back pain patient group can be compared. Suggestions are offered for the use of EMG biofeedback during dynamic lower back movements as a possible method of alleviating the pain state, perhaps by altering the patient's posture.