Responses of forearm blood flow to graded leg exercise in man.

To test whether the cutaneous vascular responses to exercise are influenced by the level of work, three strategies were followed. In each, forearm blood flow and esophageal temperature were measured throughout. In part I, the forearm blood flow-internal temperature relationships from separate sessions of steady-state exercise at different loads were compared. In part II, work load was varied between 50 and 150 W. Work load was raised or lowered 50 W every 5 min over 60-75 min. The third strategy was to examine the immediate change in forearm blood flow accompanying rapid, large increments or decrements in work load. The results do not support a graded response of the cutaneous circulation to exercise. In both the first and second protocols above, the relationship of forearm blood flow to internal temperature was not measurably altered by work load. Multiple linear regression analysis failed to reveal a consistent role for work load in part II. In the third protocol, there was no consistent or sustained response to an abrupt change in work load. Thus over the range of work loads used in this study there appears to be no major role for the level of work in the regulation of forearm skin blood flow other than through the effect on internal temperature.