Get the latest in health news delivered to your inbox! Harvard Health Publishing provides trustworthy, evidence-based health content with the authority you demand and the impact you need. People should also limit saturated fat and make sure they consume omega-3 fatty acids. They found that high-intensity strength exercise followed by sauna exerted a greater strain on neuromuscular performance than high-intensity endurance exercise or combined endurance and strength exercise followed by sauna. Firstly, an analysis of men characterized by moderate and high PA levels demonstrated that the latter had significantly higher serum TES concentrations. Correlation Coefficients of Hormone Levels Before and After sauna, Changes in Hormone Levels During the Sauna Bath, and MET Values. In the group of the examined volunteers, 19 participants were characterized by moderate PA levels and 11 participants—by high PA levels. The concentration of dehydroepiandrosterone (DHEA-S) was determined with a specific rabbit anti-DHEA-S polyclonal antibody. Body temperature was measured with a non-contact laser thermometer (Stalgast , Poland) before blood sampling. After every 12-min session, the students recovered in a neutral room (temperature of 18°C and humidity 50%–55%) in a sitting position. These changes are particularly pronounced in individuals who are not frequent sauna users (Pilch et al., 2003). The hormonal system strongly affects the thermoregulatory system, and a number of hormonal changes occur under thermal stress. The hormone-receptor complex then binds to DNA and activates the genes responsible for the production of specific proteins and enzymes (Jaskólski & Jaskólska, 2006). The production of the antidiuretic hormone (ADH) and aldosterone is intensified to normalize blood pressure (Hannuksela & Ellahham, 2001; Kauppinen, 1989). Elevated blood pressure and sweating during sauna trigger a number of responses and activate mechanisms that are responsible for the maintenance of homeostasis. Some of these changes resemble the processes that occur in response to other stressors, whereas other changes are typical of sauna-induced stress (Kukkonen-Harjula & Kauppinen, 1988). In the studied population, 23.70% of males and 14.93% of females experienced discomfort due to high temperature, a large number of participants, and the presence of the opposite sex (Podstawski et al., 2013). An increase in COR concentrations is considered a sensitive indicator of a stress reaction and intolerance of heat, which is most frequently reported in infrequent or first-time sauna users (Follenius et al., 1982). In the present study, a significant decrease in COR levels could suggest that users who regularly use the sauna (twice a week) are accustomed to extreme changes in temperature. The above could indicate that intermittent exposure to hot and cold stress partially stabilizes blood COR levels and alleviates stress in men who are regular sauna users. In a study by Remes et al. (1979), the mean increase in hormone levels tended to be greater in the well-conditioned group than in the poorly conditioned group of army recruits. No significant relationships were found for the remaining hormones (COR, PRL, and DHEA-S) or their changes during the sauna treatment. The relationships between different hormone concentrations before and after sauna and changes in these relationships in view of the participants’ PA levels (expressed in MET units) are presented in Table 2. After the sauna treatment, a very small decrease in COR concentrations was noted in men with very low baseline COR levels, and a minor increase or no change in COR concentrations were observed in four subjects. Podstawski et al. (2013) demonstrated that a visit to the sauna can be a stressful experience for people who are rarely subjected to heat therapy. Regular sauna bathing may alleviate and prevent the risk of both acute and chronic diseases (Laukkanen et al., 2019). Each sauna session was followed by a 6-min cool-down break during which the participants were immersed in cold water (10−11°C) for 1 min. Mice overexpressing the melanocortin 4 receptor (MC4R) antagonists agouti signaling protein (ASP) or agouti-related peptide (AgRP) 86- as well as rodents and humans with hypomorphic mutations in MC4R 87, disruptions of POMC gene expression 88, 89 or of proproneuropeptide (e.g., POMC, pro-ACTH, pro-TRH) processing by prohormone convertases 90, 91 - are obese. Thus, decreased circulating leptin concentrations as a result of reduced fat mass has the net effect of stimulating food intake 1. Leptin is an adipocyte derived molecule that circulates in weight-stable individuals in direct proportion to fat mass 79. However, after a few months on a high fat diet, these changes are no longer evident 74, 75, indicating that resistance to sustained increased adiposity is less sustained than resistance to decreased adiposity 69. The MET is the ratio of the work metabolic rate to the resting metabolic rate, and 1 MET denotes the amount of oxygen consumed in 1 min at rest, which is estimated at 3.5 mL/kg/min. The IPAQ was used only to select a homogenous sample of male students, and the results were presented only in terms of Metabolic Equivalent of Task (MET) units indicative of the participants’ PA levels. The participants’ PA levels were evaluated using the standardized and validated International Physical Activity Questionnaire (IPAQ) (Lee et al., 2011). Instead, rodents rely more on non-shivering thermogenesis (NST), which takes place in the brown adipose tissue (BAT) and is also referred as BAT thermogenesis. Shivering and non-shivering thermogenesis are the two major facultative thermogenic mechanisms in mammals. In the luteal phase there is an increase of ≈ 0.5 °C, when compared to the follicular phase. However, during passive and exercise heat stress, women exhibit a lower sweating rate than men (97, 98). Even during maintenance of a reduced weight, satiety remains diminished despite the decline in energy expenditure 78. During dynamic weight loss, human beings and rodents are both hungrier (willing to eat more often) and less satiated (willing to eat more per meal) 77. As noted above, the long-term constancy of body weight suggests that energy intake and expenditure vary coordinately to maintain relatively stable energy stores. The steadily increasing prevalence of obesity in humans also suggests that body fatness is facilitated more vigorously than body thinness. Brown adipose tissue (BAT) allows the uncoupling of mitochondrial substrate oxidation from ATP production thereby releasing the energy of fatty acid oxidation as heat 49.
