Changes in tone of limb veins during supine exercise1

tone of limb veins during supine exercise. J. Ap pl. Physiol. 2 o ( I): 1-8. 1g65.-Normal subjects have been studied to assess the response of the capacitance vessels in the forearm during supine leg exercise. Measurements were made of changes in forearm volume (strain-gauge and water-filled plethysmo-graphs) at a given pressure in the large forearm veins, of changes in pressure in the forearm veins with the circulation to the forearm arrested and in “isolated ” vein segments. The re-sults were consistent and demonstrated that exercise with a work load of 270-81 o kg/min caused constriction of forearm capacitance vessels via the sympathetic nerves proportional to the severity of the exercise. Venoconstriction also occurred in the hand, and in the calf during arm exercise. Local exercise of the forearm muscles during supine leg exercise, which increased forearm blood flow by dilating the resistance vessels, did no