Mechanically evoked torque and electromyographic responses during passive elbow extension in upper limb tension test position

In neural tension testing, it is critically important establish a method to investigate the relative contribution of different neuromuscular mechanisms to resistance developed during and at the limit of the upper limb tension test 1 (ULTT1). Three males and seven females in the age range 41-72 years (mean 56, SD±10) participated in a within subject repeated measure study. The study consisted of two major testing protocols. The first was an objective passive movement protocol, which utilized a KIN-COM® dynamometer to measure range of motion (ROM) and evoked resistive torque during elbow extension. The second was an electromyographic (EMG) protocol, which allowed recording of EMG from 10 shoulder and arm muscles during the controlled passive elbow extension as the last component of ULTT1. A battery-operated micro-switch held by the subject, generated digital rectangular pulses to indicate occurrence of pain onset and pain tolerance limit during the experimental task. There was increased level of EMG activity prior to pain onset (P<0.05). There was also clear evidence that elevated perception of pain and elevated levels of resistive torque (P<0.05), were positively correlated with the EMG activity in the muscles responsible for antalgic posture of the upper limb (P<0.05). From these findings, now it is possible to propose that increased detectable resistance during elbow extension at ULTT1 position involves the protective reflex activation of the shoulder and arm muscles which is mediated by nociceptive and mechano-receptors as a result of the preferential mechanical stretching of the median nerve during the test.