Effect of passive heat stress and exercise in the heat on arterial stiffness

Purpose Prior evidence indicates that acute heat stress and aerobic exercise independently reduce arterial stiffness. The combined effects of exercise and heat stress on PWV are unknown. The purpose of this study was to determine the effects of heat stress with passive heating and exercise in the heat on arterial stiffness. Methods Nine participants (n = 3 females, 47 +/- 11 years old; 24.1 +/- 2.8 kg/m(2)) completed four trials. In a control trial, participants rested supine (CON). In a passive heating trial (PH), participants were heated with a water-perfusion suit. In two other trials, participants cycled at similar to 50% of (V) over dotO(2peak) in a hot (similar to 40 degrees C; HC trial) or cool (similar to 15 degrees C; CC trial) environment. Arterial stiffness, measured by PWV, was obtained at baseline and after each intervention (immediately, 15, 30, 45, and 60 min post). Central PWV (C-PWV) was assessed between the carotid/femoral artery sites. Upper and lower peripheral PWV was assessed using the radial/carotid (U-PWV) and dorsalis pedis/femoral (L-PWV) artery sites. The mean body temperature (T-B) was calculated from the skin and rectal temperatures. Results No significant changes in T-B were observed during the CON and CC trials. As expected, the PH and HC trials elevated T-B 2.69 +/- 0.23 degrees C and 1.67 +/- 0.27 degrees C, respectively (p < 0.01). PWV did not change in CON, CC, or HC (p > 0.05). However, in the PH trial, U-PWV was reduced immediately (-107 +/- 81 cm/s) and 15 min (-93 +/- 82 cm/s) post-heating (p < 0.05). Conclusions Heat stress via exercise in the heat does not acutely change arterial stiffness. However, passive heating reduces U-PWV, indicating that heat stress has an independent effect on PWV.