The purpose of this study is to clarify the changes in oxygen saturation inside the muscle tissue compartment at rest during and during dynamic knee-extension exercise under several circumstances in six male subjects. The study was carried out under the following circumstances: standing position on the ground, sitting position on the ground, recumbent position on the ground, standing position A (depth = 77 cm) in water, and standing position B (depth = 117 cm) in water. We observed that the oxygenated hemoglobin (HbO₂) during rest was unchanged, a decrease in the amount of deoxygenated hemoglobin (HbD) commensurate with an increase in the venous return. We observed similar results when comparing the recumbent position on the ground with the standing position (B) in water, and when comparing the sitting position on the ground with the standing position (A) in water. The surface electromyograms (EMG) of latissimus dorsi muscle,vastus medialis muscle, gluteus maximus muscle and biceps femoris caput longum muscle. During the resting time, the standing position (B) in water showed a greater amount of latissimus dorsi muscle activity compared with the recumbent position on the ground by the integrated EMGs (iEMG). Changes in positions and circumstances did not produce observable changes in the tissue oxygen saturation (StO₂) and arterial blood oxygen saturation (SpO₂) during exercise. With compared the resting state any significant rise in heart rate (HR) was not observed during exercise when. Also, the iEMG of latissimus dorsi did not change when the latissimus dorsi were out of the water compared with the iEMG of latissimus dorsi of the exercise on the ground, but lower activity was observed when the latissimus dorisi were in the water. From the above results it is believed that exercise in water, as done in this study, was not done under control of muscle blood flow. it was observed in this exercise that muscle activity became less when the water level was made higher. In water 117 cm deep (xiphoid process level) approximates the physiology of the bloodstream observed in the state of lying down. This indicates that there is no overload on the heart, and moreover, that there is not much load on the muscle. Therefore, it is concluded that the nature of the exercise environment can contribute to improving joint mobility.

DESCENTE SPORTS SCIENCE Vol.22/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE