The effects of local versus systemic passive heating on the acute inflammatory, vascular and glycaemic response

The aim of this study was to compare the acute cardiometabolic and perceptual responses between local and whole-body passive heating. Using a water-perfused suit, ten recreationally active males underwent three 90 min conditions: heating of the legs with upper-body cooling (LBH), whole-body heating (WBH) and exposure to a thermoneutral temperature (CON). Blood samples were collected before and up to 3h post-session to assess inflammatory markers, while a 2h oral glucose tolerance test was initiated 1h post-session. Femoral artery shear rate and perceptual responses were recorded at regular intervals. The interleukin (IL)-6 incremental area under the curve (iAUC) was higher for LBH (1096±851 pg/mL*270min) and WBH (833±476 pg/mL*270min) compared with CON (565±325 pg/mL*270min; p<0.047). Glucose concentrations were higher after WBH compared with LBH and CON (p<0.046). Femoral artery shear rate was higher at the end of WBH (1713±409 L/min) compared with LBH (943±349 L/min; p<0.001), and higher in LBH than CON (661±222 L/min; p=0.002). Affect and thermal comfort were more negative during WBH compared with LBH and CON (p<0.010). In conclusion, local passive heating elevated shear rate and the IL-6 iAUC. However, while resulting in more positive perceptual responses, the majority of the included cardiometabolic markers were attenuated compared with WBH.