No effects of acclimation to heat on immune and hormonal responses to passive heating in healthy volunteers

Abstract

Heat acclimation results in whole body-adaptations that increase heat tolerance, and might also result in changed immune responses. We hypothesized that, after heat acclimation, tumor necrosis factor alpha, interleukin 6 and the lymphocyte count would be altered. Heat acclimation was induced in 6 healthy men by 100 min of heat exposure for 9 days. Heat exposure consisted of (1) 10 min of immersion up to chest-level in water at 42°C and (2) 90 min of passive heating by a warm blanket to maintain tympanic temperature at 37.5°C. The climatic chamber was maintained at 40°C and a relative humidity of 50%. Blood samples were analyzed before and after heat acclimation for natural killer (NK) cell activity, counts of lymphocytes B and T, before and after heat acclimation for peripheral blood morphology, interleukin 6, tumor necrosis factor alpha, and cortisol. A Japanese version of the profile of mood states questionnaire was also administered before and after acclimation. The concentrations of white blood cells, lymphocytes B and T, cortisol, interleukin 6, tumor necrosis factor alpha and NK cell activity showed no significant differences between pre- and post-acclimation, but there was a significantly lower platelet count after acclimation and, with the profile of mood states questionnaire, there was a significant rise in anger after acclimation. It is concluded that heat acclimation by passive heating does not induce alterations in immune or endocrine responses.

The Effects of Imposed Sedentary Behavior and Exercise on Energy Intake in Adolescents With Obesity

“…14,31 In 2011, Chaput et al 32 asked 22 healthy adolescents to randomly complete a 1-hour video game or 1-hour sitting condition, and found that a single video game session was associated with increased food intake, regardless of sensations appetite. Only Bergouignan et al 21 and Kanikowska et al 33,34 have shown that a medium term (15-20 days) of bed rest did not induce any change in these hormones in lean adults. The present work seems to be the first that questions the impact of imposed sedentary behavior (using bed rest) on daily energy intake regulation.…”

Effect of acute heat stress on adrenocorticotropic hormone, cortisol, interleukin-2, interleukin-12 and apoptosis gene expression in rats

“…All the data are shown as mean ± standard deviation (n=8). heat stress period, particularly the immune organ (24). In general, cell death can be divided into two patterns, necrosis and apoptosis.…”

Heat alleviation strategies for athletic performance: A review and practitioner guidelines

“…A recent review of passive methods [125] concluded that these strategies can be used to induce heat adaptations, such as a reduced resting and/or exercising T CORE [96][97][98]119,121,124], T SKIN [96,98,121], and HR [96,98,118,126]. Passive methods for HA also improve sweat onset thresholds and enhance sweat capacity [98,127].…”