Static (isometric) muscle contractions are common components of effort in performing daily activities. The problem of static exercise becomes important since isometric contractions cause marked increases in blood pressure and catecholamine levels. This study is designed to describe the relationships among age, sex, race, body weight, pattern of body fat distribution, level of physical fitness, and static exercise responses. The subjects for the study are selected from four volunteer groups: participants in the Johns Hopkins Academic Teaching Nursing Home, the Baltimore Longitudinal Study of Aging (BLSA), the Senior Athletes Study and volunteers working in this environment. They are divided into four age groups: 20-45, 45-59, 60-74 and 75 and over years. They range in obesity from lean to moderately obese and are further subdivided into subgroups of subjects representing upper and lower body segment type of obesity. The experimental protocol is the same for all subjects: sustained hand-grip exercise on a hand dynamometer at 30% of their individual maximal voluntary force to fatigue (usually 3 - 6 minutes). Before the test, at one minute intervals during the test, and 3 minutes after its termination, blood pressure, heart rate and blood samples for catecholamines, glucose and free fatty acids are taken. To date, a total of 170 subjects have been studied from several population groups. The goal of recruiting 160 subjects has just been surpassed and analyses of the results will be conducted in the coming year.
