EFFECT OF PREVIOUS POSTURE ON CARDIAC ACCELERATION AT THE BEGINNING OF EXERCISE.
CHEMICAL RESEARCH AND DEVELOPMENT LABS EDGEWOOD ARSENAL MD
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Three subjects rested in the supine position, arose quickly, and ran for 1 min on a treadmill. Then they stood erect for 1 min and ran again. For the first 30 beats at the beginning of the run, their cardiac acceleration was greater after supine than after standing rest. The acceleration after supine rest then declined. The difference in cardiac rate arising from previous posture was insignificant for the last 30 sec of the run. Environmental temperatures were 18 degrees and 46 degrees C. The initial difference in acceleration was greater at the higher temperature. The distribution of blood between the chest and the periphery contributes to the differences in the degree of acceleration of the heart at the beginning of exercise. Author