Alternate local skin cooling and heating ameliorates impaired forearm skin vasodilation function mediated by prolonged sitting

Abstract

Prolonged sitting can impair physiological functions. We hypothesized that prolonged sitting attenuates forearm cutaneous vascular function but alternating local skin cooling and heating mitigates this attenuation. Eleven young adults (five women) sat for 75 min in thermoneutral condition (25 °C) during which skin temperature at four forearm skin sites was modulated: 1) maintained at 33 °C (control), 2) reduced to 15 °C for 4 min, then rised to 40 °C, repeated 5 times, 3) maintained at 33 °C for 4 min, then rised to 40 °C for 4 min, repeated 5 times or 4) elevated to 40 °C. Before and after 75-min prolonged sitting, venoarteriolar reflex (VAR) was assessed by a reduction in cutaneous blood flow (laser Doppler flowmetry) mediated by venous occlusion, whereas post-occlusive reactive hyperemia (PORH) was assessed by increases in cutaneous blood flow following arterial occlusion. After prolonged sitting, PORH decreased at the control (mean with 95%CI: 40.2 [34.5, 45.9] %max vs. 26.3 [19.3, 33.3] %max P < 0.001), but this response was not seen at the site subjected to alternating 15 °C cooling and 40 °C heating (P = 0.983). VAR remained unchanged before and after prolonged sitting at the control (P = 0.990), but increased with 15 °C cooling and 40 °C heating (−47.8 [−61.6, −34.1] %baseline vs. -68.0 [−75.3, −60.7] %baseline P = 0.029). We show that prolonged sitting decreases forearm cutaneous vasodilation function (PORH), but this response is mitigated by alternating local skin cooling and heating. Additionally, prolonged sitting does not affect forearm cutaneous VAR, but alternating local skin cooling and heating enhances VAR.