Vasomotor responses in glabrous and nonglabrous skin during sinusoidal exercise

PURPOSE: To test whether vasomotor responses to dynamic exercise differ in glabrous and nonglabrous human skin, we determined the phase response and amplitude response of cutaneous vascular conductance in the forearm (CVCforearm), dorsal hand (CVCdorsal hand), and palm (CVCpalm) to sinusoidal exercise. METHODS: Nine healthy subjects exercised on a cycle ergometer with a constant load (35% of peak O2 uptake) for 20 min at an ambient temperature of 25 degrees C and relative humidity of 60%; for the next 40 min, they exercised with a sinusoidal load. The sinusoidal load variation ranged from 10% to 60% of peak O2 uptake over a 4-min period. Skin blood flow was monitored by laser-Doppler flowmetry. CVC was calculated from the ratio of blood flow to mean arterial pressure (MAP). RESULTS: During sitting rest and exercise, CVCpalm showed consistently higher value than CVCforearm and CVCdorsal hand. During sinusoidal exercise, the amplitude in CVCpalm was 7.4 times and 3.2 times greater than those in CVCforearm and CVCdorsal hand, respectively (P < 0.05). The phase difference in CVCforearm and CVCdorsal hand were smaller than that in CVCpalm (P < 0.05). CONCLUSION: These findings of significant differences in phase and amplitude of responses in CVC between glabrous and nonglabrous skin during cyclic changes of dynamic exercise load suggest functionally important differences in the reflex control of these regions of skin.