A comparative study was made on bathing-induced changes in body temperature, blood pressure, pulse rate and tissue blood flow of 12 healthy adults using tap water and artificial CO₂ water at 37°C to clarify the physiological effects of CO₂ at various concentrations of 0, 100, 300, 600, 800 and 1000ppm. There was no change in body temperature during bathing in either water, whereas blood pressure and pulse rate were similarly decreased during bathing, but either of these decreases was not significantly different between tap water and CO₂-water. Therefore, it seemed that the decrease in blood pressure due to vasodilation during bathing would be controlled through some regulatory system like autonomic nerve system not so as to result in too much decrease. But, tissue blood flow was more increased during bathing in CO₂-water than tap water, suggesting that blood circulation in the tissue near skin surface would have been more enhanced by bathing in hot CO₂-water, resulting in a decrease of blood pressure.
Since the increase in tissue blood flow during bathing was dependent on the concentration of CO₂, it seemed that an improvement of tissue circulation and metabolism would have resulted from venous return increase associated to venous dilatation, one of dose-dependent CO₂ effects.

Electromyographic muscle activities of the shoulder muscles during shoulder external rotation with reference to load magnitude were studied in 8 healthy male subjects without history of shoulder injuries. In addition, we discussed the relationship between rotator cuff muscles and superficial muscles. The subjects performed shoulder external rotation from 60°internal rotation to 45° external rotation at 20° of shoulder abduction and 20° of flexion. A Cybex dynamometer used to prescribe angle and velocity of the shoulder movement. At the same time, intramuscular wire electrodes were inserted into the supraspinous, infraspinous and teres minor muscles, and then surface electrodes were placed over the posterior deltoid and middle trapezius muscles. The load magnitude ranged 2-18 Nm and the angle velocity was set at 15 deg/sec. The rotator cuff muscles became significantly to be activated from 2 Nm (the supraspinous and infraspinous m.) and from 4-5 Nm (the teres minor m.) compared with the muscle activity during non-load. The superficial muscles became significantly to be activated from 4-7 Nm (the posterior deltoid m.) and from 3-6 Nm (the middle trapezius m.) compared with the muscle activity during non-load. Within the load range (18 Nm 46.8% MVC), %iEMG of the rotator cuff muscles was always larger than that of the superficial muscles. Therefore, we concluded that the contribution of the rotator cuff muscles was larger than that of the superficial muscles up to 3-4 Nm, and activities of the superficial muscles increased gradually from 3-4 Nm during shoulder external rotation.

An instantaneous blood pressure measuring system at the wrist based on the volume-compensation method is developed, and the characteristics and accuracy of the system is evaluated. The radial artery at the wrist is used as the detecting object, and a pad-type cuff as well as a newly designed electro- pneumatic converter is used in the system. Also, the comparative experiments between the system and the invasive blood measuring device (direct method) indicated that, the results obtained from the two methods are well correlated not only in rest condition, but also in a stressful condition. Therefore, the system is capable of non-invasive measuring instantaneous blood pressure in the radial artery.
Blood Pressure Determination ; instrumentation ; methods ; Equipment Design ; Humans ; Radial Artery ; physiology