Forearm-finger skin temperature gradient as an index of cutaneous perfusion during steady-state exercise.

The purpose of this study was to examine whether the forearm-finger skin temperature gradient (T(forearm-finger)), an index of vasomotor tone during resting conditions, can also be used during steady-state exercise. Twelve healthy men performed three cycling trials at an intensity of ~60% of their maximal oxygen uptake for 75 min separated by at least 48 h. During exercise, forearm skin blood flow (BFF ) was measured with a laser-Doppler flowmeter, and finger skin blood flow (PPG) was recorded from the left index fingertip using a pulse plethysmogram. T(forearm-finger) of the left arm was calculated from the values derived by two thermistors placed on the radial side of the forearm and on the tip of the middle finger. During exercise, PPG and BFF increased (P<0.001), and T(forearm-finger) decreased (P<0.001) from their resting values, indicating a peripheral vasodilatation. There was a significant correlation between T(forearm-finger) and both PPG (r = -0.68; P<0.001) and BFF (r = -0.50; P<0.001). It is concluded that T(forearm-finger) is a valid qualitative index of cutaneous vasomotor tone during steady-state exercise.