The purpose of this study is to observe the effect of body position on circulatory responses and muscular endurance work capacity. Thirty four subjects participated in the study. Body position used to this study were three kinds. Horizontal-supine position(S), Head-down position(D), Head-up position(U). Each subject performed hand grip exercise in three different body positions. Forearm and lower leg blood flow was measured by using mercury-in-rubber strain gauge method. Blood sample were obtained from cubital vein and brachial artery in selected ten subjects. The results were summarized as follows : 1) The significant difference of resting blood flow was observed among three body positions. 2) In work of one-third work load of maximal hand grip strength, significant difference of performance was not observed among three body positions, but in 1/6 max. work, significant difference was observed between Head-up position and other two body positions. 3) As to the peak blood flow, difference between Head-up position and other two body positions was statistically significant. 4) Blood lactate and arterial-venous oxygen difference of immediately after exercise showed highest value in Head-up position. 5) Circulatory responses with body position change (hydrostatic effect, nervous regulation, etc.) seem to have influence on endurance work capacity. The longer the work time become, the more remarkable the effect of body position seem to be remarkable
