Introduction Surrounding the concept of muscle tension one finds considerable ambiguity. Not only are there many different definitions of the term,2but the methods of measurement are quite varied.9Because of this state of affairs, conclusions from a single study, as well as generalizations from one study to the next, become questionable. While many recent investigators have agreed that the electromyograph is the most sensitive measure of muscle tension,9disagreement still exists regarding the muscle groups from which recordings are to be taken. Since there is some evidence of a lack of consistency in tension for a given muscle group under varying conditions,27,46this presents a problem. Related to such a problem is the question of whether most individuals respond to varying conditions with similar levels of tension in all of the body musculature. In other words, does a general factor of muscle