Symptoms of anxiety and tension and the accompanying physiological changes in the muscular system.

It has already been shown that anxiety is often accompanied by muscle over-activity (Jacobson, 1938). Malmo and Shagass (1949a) found that the amplitude of action potentials recorded from the neck muscles of patients with anxiety states was significantly higher than in healthy controls when both were stressed by applying painful stimuli to the forehead; but the action-potential ratings also correlated with movements drawing the head away from the stimulus. Malmo and Shagass (1949b) used the same technique when they found that anxious patients with head complaints had significantly more activity in the neck muscles during stress than those without. Wolff (1948) also recorded over-activity in the electromyograms of the neck and scalp muscles of anxious patients. When the anxiety was diminished the over-activity and the headache disappeared. Finally, Holmes and Wolff (1952) found that patients with backache had pain and a generalized over-activity of the trunk muscles in situations which engendered conflict and insecurity, or feelings of hostility, frustration, and guilt. As the findings in the last two papers were presented in the form of typical case histories it was not possible to estimate how regularly headache or backache and muscular over-activity were associated. We aimed, by means of controlled experiments, to study the relations between the symptoms complained of by anxious patients and the activity in the skeletal muscles. In order to limit the experimental conditions to the simplest we measured the muscle activity occurring in our subjects when they were relaxing, remaining still, and, where possible, in a position which avoided reflex postural tone in the muscles being investigated. The activity recorded under these conditions we called muscle tension. Our hypotheses were first, that an increase in innervation of the skeletal muscles accompanies anxiety so that in anxious patients attempting to relax not only will muscle tension be greater than in healthy subjects, but those patients with most clinical evidence of anxiety and " tension" will have the most muscle tension. It follows that the increase in muscle activity expected in the anxious would be evident in a number of well separated groups of voluntary muscles. Secondly, that the physiological mechanism underlying some of the common symptoms of anxiety is increased muscle.tension, so that more muscle tension would be recorded in muscles in which such symptoms were felt than in those where they were not.