Local cooling during hot water immersion improves perceptions without inhibiting the acute interleukin-6 response
R. G. Mansfield, Sven P. Hoekstra, Joana Bill, Christof A. Leicht
Abstract
Abstract Purpose Passive elevation of body temperature can induce an acute inflammatory response that has been proposed to be beneficial; however, it can be perceived as uncomfortable . Here, we investigate whether local cooling of the upper body during hot water immersion can improve perception without inhibiting the interleukin-6 (IL-6) response. Methods Nine healthy male participants (age: 22 ± 1 years, body mass: 83.4 ± 9.4 kg) were immersed up to the waist for three 60-min water immersion conditions: 42 °C hot water immersion (HWI), 42 °C HWI with simultaneous upper-body cooling using a fan (FAN), and 36 °C thermoneutral water immersion (CON). Blood samples to determine IL-6 plasma concentration were collected pre- and post-water immersion; basic affect and thermal comfort were assessed throughout the intervention. Results Plasma IL-6 concentration was higher for HWI and FAN when compared with CON ( P < 0.01) and did not differ between HWI and FAN ( P = 0.22; pre to post, HWI: 1.0 ± 0.6 to 1.5 ± 0.7 pg·ml −1 , FAN: 0.7 ± 0.5 to 1.1 ± 0.5 pg·ml −1 , CON: 0.5 ± 0.2 to 0.5 ± 0.2 pg·ml −1 ). At the end of immersion, basic affect was lowest for HWI (HWI: − 1.8 ± 2.0, FAN: 0.2 ± 1.6, CON 1.0 ± 2.1, P < 0.02); thermal comfort for HWI was in the uncomfortable range (3.0 ± 1.0, P < 0.01 when compared with FAN and CON), whereas FAN (0.7 ± 0.7) and CON (-0.2 ± 0.7) were in the comfortable range. Conclusion Local cooling of the upper body during hot water immersion improves basic affect and thermal comfort without inhibiting the acute IL-6 response.