Background: Infrared thermography is a growing area of interest in sports science due to the potential of skin temperature (T-sk) measurements to provide valuable information from rest to exercise.... Show moreBackground: Infrared thermography is a growing area of interest in sports science due to the potential of skin temperature (T-sk) measurements to provide valuable information from rest to exercise. However, limited research exists on T-sk in older adults and the impact of factors such as sex and cardiorespiratory fitness (CRF) on T-sk. This study aims to investigate T-sk at rest and after acute exercise in older adults and assess whether sex or CRF influences T-sk.Methods: Ninety-two participants (41 women, 68.48 +/- 3.01 years) were examined with a thermographic camera in a conditioned room (23.02 +/- 3.01 degrees C) at rest and after a graded protocol. The T-sk of 25 regions of interest (ROIs) were extracted and analysed.Results: Men had higher overall T-sk at rest in 76% of ROIs, showing significant differences (p < 0.010) in six specific ROIs, independent of CRF. Both sexes had similar T-sk responses after graded exercise, with increases in distal parts (1.06 +/- 0.50 C-degrees), decreases in proximal parts (-0.62 +/- 0.42 degrees C), and stable central T-sk (0.23 +/- 0.59 degrees C). Increases in lower limb T-sk were significantly associated with CRF in men and women (beta = 0.438, p = 0.001, and beta = 0.535, p < 0.001, respectively), explaining 17% and 27% of the variance, respectively.Conclusions: This study demonstrates a sex-specific effect on resting T-sk in older adults, suggesting that sex-specific T-sk patterns should be considered when analysing T-sk in this population. Additionally, the association between increases in lower limb T-sk and CRF suggests that T-sk could be a promising predictor of CRF in older adults. Show less
Purpose: Brown adipose tissue (BAT) increases metabolic heat production in response to cold exposure. Body size and composition are involved in the human cold response, yet the influence of BAT... Show morePurpose: Brown adipose tissue (BAT) increases metabolic heat production in response to cold exposure. Body size and composition are involved in the human cold response, yet the influence of BAT herein have not fully been explored. Here, we aimed to study the association of the cold-induced shivering threshold time with body composition, BAT, the perception of shivering and skin temperature in young adults. Methods: 110 young healthy adults (81 females; age = 21.7 +/- 2.1 years, BMI = 24.2 +/- 4.3 kg/m2) underwent 2 h of individualized cooling, followed by the quantification of BAT using a18F-fluorodeoxyglucose ([18F]FDG) positron emission tomography-computed tomography (PET-CT) scan. Body mass index (BMI), lean mass, fat mass and body surface area (BSA) were also measured. Shivering threshold time was defined as the time until shivering occurred using an individualized cooling protocol. Results: The shivering threshold time was on average 116.1 min for males and 125.8 min for females, and was positively associated to BMI (beta = 3.106; R2 = 0.141; p = 0.001), lean mass (beta = 2.295; R2 = 0.128; p = 0.001) and fat mass (beta = 1.492; R2 = 0.121; p = 0.001) in females, but not in males (all p >= 0.409). The shivering threshold time was positively associated with BSA in males (p = 0.047) and females (p = 0.001), but it was not associated with BAT volume or [18F]FDG uptake nor with the perception of shivering and skin temperature perception in both sexes. Conclusion: The shivering threshold time is positively associated with whole-body adiposity and lean mass in females, but not in males. The shivering threshold time was positively associated with BSA, but no association was observed with BAT nor with the perception of shivering or skin temperature. Future research should consider the influence of body composition when applying cooling protocols among individuals with different phenotypical features. Show less
Straat, M.E.; Martinez-Tellez, B.; Janssen, L.G.M.; Veen, S. van; Eenige, R. van; Kharagjitsing, A.V.; ... ; Boon, M.R. 2022
Objectives: Although cold exposure is commonly believed to be causally related to acute viral respiratory infections, its effect on the immune system is largely unexplored. In this study, we... Show moreObjectives: Although cold exposure is commonly believed to be causally related to acute viral respiratory infections, its effect on the immune system is largely unexplored. In this study, we determined transcript levels of a large panel of immune genes in blood before and after cold exposure. We included both Dutch Europid and Dutch South Asian men to address whether the immune system is differently regulated in the metabolically vulnerable South Asian population.Methods: Fasted blood samples were obtained from nonobese Dutch Europid (n = 11; mean age 26 +/- 3 y) and Dutch South Asian (n = 12; mean age 28 +/- 3 y) men before and directly after short-term (similar to 2.5 h) mild cold exposure. Transcript levels of 144 immune genes were measured using a dual-color reverse transcriptase multiplex ligation-dependent probe amplification (dcRT-MLPA) assay.Results: Cold exposure acutely upregulated mRNA levels of GNLY (+35%, P < 0.001) and PRF1 (+45%, P < 0.001), which encode cytotoxic proteins, and CCL4 (+8%, P < 0.01) and CCL5 (+5%, P < 0.05), both proinflammatory chemokines. At thermoneutrality, mRNA levels of four markers of the nucleotide-binding oligomerization domain (NOD)-like receptor (NLR)-family, involved in inflammasomes, were lower in Dutch South Asians compared to Dutch Europids, namely NLRP2 (-57%, P < 0.05), NLRP7 (-17%, P < 0.05), NLRP10 (-21%, P < 0.05), and NLRC4 (-23%, P < 0.05).Conclusions: Mild cold exposure acutely increases mRNA levels of genes involved in cytotoxicity of immune cells in blood. In addition, Dutch South Asians display lower circulating mRNA levels of inflammasome genes compared to Dutch Europids. Show less
Where people live and work together it is not always possible to modify the ambient temperature; ways must therefore be found that allow individuals to feel thermally comfortable in such settings.... Show moreWhere people live and work together it is not always possible to modify the ambient temperature; ways must therefore be found that allow individuals to feel thermally comfortable in such settings. The Embr Wave (R) is a wrist-worn device marketed as a 'personal thermostat' that can apply a local cooling stimulus to the skin. The aim of the present study was to determine the effect of an intermittent mild cold stimulus of 25 degrees C for 15-20 s every 5 min over 3.5 days under free-living conditions on 1) skin temperature, 2) perception of skin temperature, 3) sleep quality and 4) resting energy expenditure (REE) in young, healthy adults. Ten subjects wore the device for 3.5 consecutive days. This intervention reduced distal skin temperature after correcting for personal ambient temperature (P < 0.05), but did not affect the subjects' the perception of skin temperature, sleep quality or REE (all P >= 0.051). Thus, this intermittent mild cold regime can reduce distal skin temperature, and wearing it under free-living conditions for 3.5 days does not seem to impair the perception of skin temperature and sleep quality or modify REE. Show less
Brown adipose tissue (BAT) thermogenic activity is commonly assessed with a positron emission tomography with computed tomography scan (PET/CT). This technique has several limitations and... Show moreBrown adipose tissue (BAT) thermogenic activity is commonly assessed with a positron emission tomography with computed tomography scan (PET/CT). This technique has several limitations and alternative techniques are needed. Supraclavicular skin temperature measured with iButtons and infrared thermography (IRT) has been proposed as an indirect marker of BAT activity. We studied the concurrent validity of skin temperature measured with iButtons vs. IRT and the association of supraclavicular skin temperature measured with iButtons and IRT with BAT. We measured skin temperature upon a shivering threshold test with iButtons and IRT in 6 different regions in 12 participants (n = 2 men). On a separate day, we determined supraclavicular skin temperature with an iButton and IRT after 2 h of a personalized cooling protocol. Thereafter, we quantified BAT volume and activity by PET/CT. We observed that the absolute differences between the devices were statistically different from 0 (all P < 0.05) after the shivering threshold test. Moreover, we did not find any association between supraclavicular skin temperature measured with iButtons or IRT and BAT F-18-FDG activity (r = -0.213; P = 0.530 and r = -0.079; P = 0.817). However, we observed a negative association of supraclavicular skin temperature measured by IRT with BAT F-18-FDG volume (r = -0.764; P = 0.006), but not with supraclavicular skin temperature measured with iButtons (r = -0.546; P = 0.082). In light of these results, we concluded that the measurement of skin temperature obtained by iButtons and IRT are not comparable. Furthermore, it seems that supraclavicular skin temperature is not associated with BAT F-18-FDG activity, but it appears to be negatively associated with BAT F-18-FDG volume in the case of IRT. Show less
Currently, 18 [F]-Fluorodeoxyglucose (F-18-FDG) in combination with a positron emission tomography/computed tomography (PET/CT) scan analysis is the most commonly used method to quantify human BAT... Show moreCurrently, 18 [F]-Fluorodeoxyglucose (F-18-FDG) in combination with a positron emission tomography/computed tomography (PET/CT) scan analysis is the most commonly used method to quantify human BAT volume and activity. However, this technique presents several drawbacks which negatively affect participant's health. The aim of the present work is to determine whether supraclavicular skin temperature can be used as an indirect marker of cold-induced BAT and skeletal muscle F-18-FDG uptake in adults, while taking into account body composition. We performed a personalized cooling protocol just before an F-18-FDG-PET/CT scan, and we measured supraclavicular skin temperature before (in warm conditions) and after the cooling protocol in 88 adults (n = 57 women, mean age: 21.9 +/- 2.1 years old, body mass index: 24.5 +/- 4.3 km/m(2)). We found that supraclavicular skin temperature at the warm and cold periods was weakly and positively associated with BAT activity (SUVmean and SUVpeak: beta = 3.000; R-2 = 0.072; P = 0.022 and beta = 2.448; R-2 = 0.060; P = 0.021), but not with skeletal muscle F-18-FDG uptake, after controlling for body composition. We performed further analyses and the positive associations persisted only in the group of women. In conclusion, supraclavicular skin temperature in warm and cold conditions seems to be related with cold-induced F-18-FDG uptake by BAT only in women, although the low explained variance of these associations means that there are other factors involved in the supraclavicular skin temperature. Show less
