Muscle tenderness or stiffness is generally attributed to local muscle spasm or aggravated tonus however electro-myographic studies have indicated no spontaneous discharge as usual and any kind of change of N M U weve patterns, certainly. There is a great deal of uncertainty about the fundamental chracter, identified factor of these conditions.
To analize (_??_-S curves) -the mean inteerval (_??_) of the single unit NMU discharges and the standard deviation (S) of the same it was learned that these phenomena could be classified into two types of muscle activities, the one is kinetic activity (K-curve) and the other is tonic one (T-curve) so to speak. We conducted examinations concerning about the character of the notor unit activity of the trigger point in low back pain patient with _??_-S relation. In comparison with the distribution of (_??_-S) of the low back pain patient group (14 patients, 295 units) and that of the control group most (_??_) was up to about 120 msec. with (S) relatively stable, an almost horizontal distribution along the x-axis with an increase when (_??_) was any larger.
As compared to this, in most examples in the lumbago group (_??_) was horizontally up to 120 msec. after which a gradual rise xas indicated. The various distributions showed that that of the lumbago group was moved to the right of the awis of co-ordination as was the recovery line. Consequently, we observed that the NMU discharges of the trigger point in low back pain patients showed more tonic activity than that of normal subjects. And this finding strongly indicates that voluntary muscular activity in trigger points is under the predominant influence of spinal motoneuron than homonymous neuron segmentally.