The Effect of Partial Pressure on Upper Extremity upon Skin and Electromyogram Temperature

Abstract

In order to design the clothing needs, such as pressure suits, to pressurize the human body, it is important to investigate the appropriate methods which diminish physiological problems against the pressure. The purpose of this study was to examine the effects of partial pressure on the upper extremity upon the skin temperature (Ts) and the electromyogram (EMG). Five female students were used as subjects. In the experiment of Ts, the forearm or the upperarm of the right upper extremity was pressured with the cuff (4 cm in width) inflated at 30 or 60 mmHg for 60min. Ts of the trunk and the leg were not changed by the pressure regardless of pressurized region. In the case of the pressure applied to the right upperarm, Ts of the forearm and the back of hand in both upper extremities were decreased. There was nd siguifcant difference in the degree of the decrease (ΔTs) between pressures in the right upper extremity. However, in the left upper extremity, ΔTs obtaind by the pressure of 30 mmHg was large compared to that measured by the pressure of 60 mmHg. In the case of the pressure applied to the right forearm, there was no change in Ts itself in both extremities when the pressure was 30 mmHg. The decrease of Ts in both extremities when the pressure was 60mmHg, was the same as that of non-pressure perid. It was inferred that the alterlation of Ts in the left upper extremity was caused by the action of so-called pressure reflex named by TAKAGI (1951). And it was assumed that the action of pressure reflex might have changed by the pressurized region. The muscle work was performed with the upperarm horizontal and the forearm flexed at 90". The load was adjusted with the initial contraction level of m. biceps brachil at the beginning of work to 25 % MVC. The work continued for 4 min and then repeated for 2 min after 2 min rest. The EMG of the m. flexor carpi ulnaris and the m. biceps brachii were measured. Prior to the exercise, the m. biceps brachii was pressurized by the cuff (4 cm in width) inflated at 30 or 60 mmHg for 5, 30, or 60 min. The pressure was also applied during exercise. The integrated EMG of the m. biceps brachii increased during the exercise for non-pressure period. However, this increase was not shown when the pressure applied above 30 min before exercise. In the repeated work, though EMG increased in all cases, the level of integrated EMG when the pressure applied above 30 min was less than that of non-pressure period.