scholarly journals Interactions of mild hypothermia and hypoxia on finger vasoreactivity to local cold stress

2019 ◽  
Vol 317 (3) ◽  
pp. R418-R431 ◽  
Author(s):  
Michail E. Keramidas ◽  
Roger Kölegård ◽  
Igor B. Mekjavic ◽  
Ola Eiken
Keyword(s):  
Cold Stress ◽  
Thermal State ◽  
Mild Hypothermia ◽  
Thermal Sensation ◽  
Interactive Effects ◽  
Whole Body ◽  
Affective Valence ◽  
Local Cooling ◽  
Air Exposure ◽  
Cold Provocation

We examined the interactive effects of mild hypothermia and hypoxia on finger vasoreactivity to local cold stress. Eight male lowlanders performed, in a counterbalanced order, a normoxic and a hypoxic (partial pressure of oxygen: ~12 kPa) hand cold provocation (consisting of a 30-min immersion in 8°C water), while immersed to the chest either in 21°C [cold trials; 0.5°C fall in rectal temperature (Trec) from individual preimmersion values], or in 35.5°C water, or while exposed to 27°C air. The duration of the trials was kept constant in each breathing condition. Physiological (Trec, skin temperature, cutaneous vascular conductance, oxygen uptake) and perceptual (thermal sensation and comfort, local pain, affective valence) reactions were monitored continually. Hypoxia accelerated the drop in Trec by ~14 min ( P = 0.06, d = 0.67). In the air-exposure trials, hypoxia did not alter finger perfusion during the local cooling, whereas it impaired the finger rewarming response following the cooling ( P < 0.01). During the 35.5°C immersion, the finger vasomotor tone was enhanced, especially in hypoxia ( P = 0.01). Mild hypothermia aggravated finger vasoconstriction instigated by local cooling ( P < 0.01), but the response did not differ between the two breathing conditions ( P > 0.05). Hypoxia tended to attenuate the sensation of coldness ( P = 0.10, r = 0.40) and thermal discomfort ( P = 0.09, r = 0.46) in the immersed hand. Both in normoxia and hypoxia, the whole body thermal state dictates the cutaneous vasomotor reactivity to localized cold stimulus.

Exploring the effect of mattress cushion materials on human–mattress interface temperatures, pre-sleep thermal state and sleep quality

2020 ◽  
pp. 1420326X2090337
Author(s):  
Xiaxia Li ◽  
Bo Zhou ◽  
Liming Shen ◽  
Zhihui Wu
Keyword(s):  
Sleep Quality ◽  
Thermal State ◽  
Thermal Environment ◽  
Thermal Sensation ◽  
Cold Climate ◽  
The Body ◽  
Whole Body ◽  
Interface Temperature ◽  
Body Parts ◽  
Human Thermal Comfort

A comfortable mattress can create a good sleep environment, but the thermal behaviour of the interaction between the human body and mattress materials is still not well understood. The effect of mattress materials on human–mattress interface temperature and human thermal state was evaluated by subjective questionnaire and measurements to detemine the human–mattress interface temperatures of the whole body and various locations of the body (WTH-M and ETH-M). The woollen fabric and polymeric foam of mattresses were evaluated as optimal cushion materials; these were indicated by measurements at 15.5 and 20°C, due to the higher WTH-M and ETH-M. Moreover, the interface temperatures measured at the back, buttock and thigh were higher with most materials than at other parts of the body, indicating a lower temperature response at the body extremities due to the body–mattress interface. Under the cold climate, people would prefer warm thermal sensation rather than the neutral thermal feeling. There should be more consideration on the thermal insulation of the extremities such as the feet. The human thermal response was not only affected by mattress materials, but also by body parts and indoor air temperatures. These findings are important to understand the heat transfer and human thermal comfort requirements, providing a comfortable thermal environment to ensure sleep quality.

Effects of Face Mask Use on Objective and Subjective Measures of Thermoregulation During Exercise in the Heat

2021 ◽  
pp. 194173812110282
Author(s):  
Ayami Yoshihara ◽  
Erin E. Dierickx ◽  
Gabrielle J. Brewer ◽  
Yasuki Sekiguchi ◽  
Rebecca L. Stearns ◽  
...  
Keyword(s):  
Exercise Intensity ◽  
Thermal Sensation ◽  
Face Mask ◽  
Whole Body ◽  
Moderate Exercise ◽  
Physically Active ◽  
Time Points ◽  
The Face ◽  
And Control ◽  
Moderate Exercise Intensity

Background: While increased face mask use has helped reduce COVID-19 transmission, there have been concerns about its influence on thermoregulation during exercise in the heat, but consistent, evidence-based recommendations are lacking. Hypothesis: No physiological differences would exist during low-to-moderate exercise intensity in the heat between trials with and without face masks, but perceptual sensations could vary. Study Design: Crossover study. Level of Evidence: Level 2. Methods: Twelve physically active participants (8 male, 4 female; age = 24 ± 3 years) completed 4 face mask trials and 1 control trial (no mask) in the heat (32.3°C ± 0.04°C; 54.4% ± 0.7% relative humidity [RH]). The protocol was 60 minutes of walking and jogging between 35% and 60% of relative VO2max. Rectal temperature (Trec), heart rate (HR), temperature and humidity inside and outside of the face mask (Tmicro_in, Tmicro_out, RHmicro_in, RHmicro_out) and perceptual variables (rating of perceived exertion (RPE), thermal sensation, thirst sensation, fatigue level, and overall breathing discomfort) were monitored throughout all trials. Results: Mean Trec and HR increased at 30- and 60-minute time points compared with 0-minute time points, but no difference existed between face mask trials and control trials ( P > 0.05). Mean Tmicro_in, RHmicro_in, and humidity difference inside and outside of the face mask (ΔRHmicro) were significantly different between face mask trials ( P < 0.05). There was no significant difference in perceptual variables between face mask trials and control trials ( P > 0.05), except overall breathing discomfort ( P < 0.01). Higher RHmicro_in, RPE, and thermal sensation significantly predicted higher overall breathing discomfort ( r2 = 0.418; P < 0.01). Conclusion: Face mask use during 60 minutes of low-to-moderate exercise intensity in the heat did not significantly affect Trec or HR. Although face mask use may affect overall breathing discomfort due to the changes in the face mask microenvironment, face mask use itself did not cause an increase in whole body thermal stress. Clinical Relevance: Face mask use is feasible and safe during exercise in the heat, at low-to-moderate exercise intensities, for physically active, healthy individuals.

Acute cold stress in rheumatoid arthritis inadequately activates stress responses and induces an increase of interleukin 6

2008 ◽  
Vol 68 (4) ◽  
pp. 572-578 ◽  
Author(s):  
R H Straub ◽  
G Pongratz ◽  
H Hirvonen ◽  
T Pohjolainen ◽  
M Mikkelsson ◽  
...  
Keyword(s):  
Rheumatoid Arthritis ◽  
Stress Response ◽  
Cold Stress ◽  
Stress Responses ◽  
Plasma Levels ◽  
Acute Stress ◽  
Whole Body ◽  
Cold Therapy ◽  
Before And After ◽  
Sympathetic Stress

Objective:Acute stress in patients with rheumatoid arthritis (RA) should stimulate a strong stress response. After cryotherapy, we expected to observe an increase of hormones of the adrenal gland and the sympathetic nervous system.Methods:A total of 55 patients with RA were recruited for whole-body cryotherapy at −110°C and −60°C, and local cold therapy between −20°C and −30°C for 7 days. We measured plasma levels of steroid hormones, neuropeptide Y (sympathetic marker), and interleukin (IL)6 daily before and after cryotherapy.Results:In both therapy groups with/without glucocorticoids (GC), hormone and IL6 levels at baseline and 5 h after cold stress did not change over 7 days of cryotherapy. In patients without GC, plasma levels of cortisol and androstenedione were highest after −110°C cold stress followed by −60°C or local cold stress. The opposite was found in patients under GC therapy, in whom, unexpectedly, −110°C cold stress elicited the smallest responses. In patients without GC, adrenal cortisol production increased relative to other adrenal steroids, and again the opposite was seen under GC therapy with a loss of cortisol and an increase of dehydroepiandrosterone. Importantly, there was no sympathetic stress response in both groups. Patients without GC and −110°C cold stress demonstrated higher plasma IL6 compared to the other treatment groups (not observed under GC), but they showed the best clinical response.Conclusions:We detected an inadequate stress response in patients with GC. It is further shown that the sympathetic stress response was inadequate in patients with/without GC. Paradoxically, plasma levels of IL6 increased under strong cold stress in patients without GC. These findings confirm dysfunctional stress axes in RA.

scholarly journals Evaluation of the interactive effects of air exposure duration and water temperature on the condition and survival of angled and released fish

2007 ◽  
Vol 86 (2-3) ◽  
pp. 169-178 ◽  
Author(s):  
Andrew J. Gingerich ◽  
Steven J. Cooke ◽  
Kyle C. Hanson ◽  
Michael R. Donaldson ◽  
Caleb T. Hasler ◽  
...  
Keyword(s):  
Water Temperature ◽  
Exposure Duration ◽  
Interactive Effects ◽  
Air Exposure

scholarly journals The effect of mild whole-body cold stress on isometric force control during hand grip and key pinch tasks

2020 ◽  
Vol 89 ◽  
pp. 102537
Author(s):  
Julie Renberg ◽  
Øystein Nordrum Wiggen ◽  
Juha Oksa ◽  
Kristine Blomvik Dyb ◽  
Randi Eidsmo Reinertsen ◽  
...  
Keyword(s):  
Cold Stress ◽  
Force Control ◽  
Isometric Force ◽  
Whole Body ◽  
Hand Grip

scholarly journals The nitric oxide dependence of cutaneous microvascular function to independent and combined hypoxic cold exposure

2020 ◽  
Vol 129 (4) ◽  
pp. 947-956
Author(s):  
Josh T. Arnold ◽  
Alex B. Lloyd ◽  
Stephen J. Bailey ◽  
Tomomi Fujimoto ◽  
Ryoko Matsutake ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Nitrite Reduction ◽  
Whole Body ◽  
Local Cooling ◽  
Cutaneous Reflex ◽  
Body Cooling ◽  
Whole Body Cooling ◽  
Oxide Removal ◽  
Oxide Synthase

When separated from local cooling, whole body cooling elicited cutaneous reflex vasoconstriction via mechanisms independent of nitric oxide removal. Hypoxia elicited cutaneous vasodilatation via mechanisms mediated primarily by nitric oxide synthase, rather than xanthine oxidase-mediated nitrite reduction. Cold-induced vasoconstriction was blunted by the opposing effect of hypoxic vasodilatation, whereas the underpinning mechanisms did not interrelate in the absence of local cooling. Full vasoconstriction was restored with nitric oxide synthase inhibition.

Cardiac autonomic function during hypothermia and its measurement repeatability

2019 ◽  
Vol 44 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Gary J. Hodges ◽  
Steven A.H. Ferguson ◽  
Stephen S. Cheung
Keyword(s):  
Heart Rate ◽  
Rectal Temperature ◽  
Mild Hypothermia ◽  
Core Body Temperature ◽  
Intraclass Correlation ◽  
Low Frequency ◽  
Whole Body ◽  
Body Cooling ◽  
Mean Square Difference ◽  
Whole Body Cooling

This study examined the effect of mild hypothermia (a 0.5 °C decrease in rectal temperature) on heart rate variability (HRV), with the identical hypothermia protocol performed twice and compared using intraclass correlation coefficient (r) analysis to study the repeatability. Twelve healthy males each completed 1 neutral (23 °C) and 2 cold (0 °C) trials. In the neutral trial, participants sat quietly for 30 min. In the cold trials, baseline data were obtained from a 5-min sample following 30 min of quiet sitting at 23 °C, followed by passive exposure to 0 °C; hypothermic measures were taken from a 5-min period immediately prior to rectal temperature decreasing by 0.5 °C. HRV was obtained from a 3-lead electrocardiogram. There were no differences (all p > 0.05) in baseline measures between the neutral and the 2 cold trials, suggesting no precooling anxiety related to the cold trials. Heart rate, together with HRV measures (i.e., root mean square difference of successive normal RR intervals, triangular interpolation of NN interval histogram, low-frequency oscillations (LF), and high-frequency oscillations (HF)), increased (all p < 0.05) with mild hypothermia and showed excellent reliability between the 2 cold trials (all r ≥ 0.81). In contrast, the LF/HF ratio decreased (p < 0.05) and had only fair reliability between the 2 cold trials (r = 0.551). In general, hypothermia led to increases in heart rate, together with most measures of HRV. Although it was counterintuitive that both sympathetic and vagal influences would increase simultaneously, these changes likely reflected increased stress from whole-body cooling, together with marked cardiovascular strain and sympathetic nervous system activity from shivering to defend core body temperature. An important methodological consideration for future studies is the consistent and repeatable HRV responses to hypothermia.

Metabolic, thermoregulatory, and perceptual responses during exercise after lower vs. whole body precooling

2003 ◽  
Vol 94 (3) ◽  
pp. 1039-1044 ◽  
Author(s):  
Andrea T. White ◽  
Scott L. Davis ◽  
Thad E. Wilson
Keyword(s):  
Heat Storage ◽  
Thermal Sensation ◽  
Submaximal Exercise ◽  
Whole Body ◽  
Lower Body ◽  
Mean Body Temperature ◽  
Thermal Discomfort ◽  
Healthy Men ◽  
Metabolic Heat ◽  
Body Heat

The purpose of this investigation was to compare the thermoregulatory, metabolic, and perceptual effects of lower body (LBI) and whole body (WBI) immersion precooling techniques during submaximal exercise. Eleven healthy men completed two 30-min cycling bouts at 60% of maximal O2uptake preceded by immersion to the suprailiac crest (LBI) or clavicle (WBI) in 20°C water. WBI produced significantly lower rectal temperature (Tre) during minutes 24–30 of immersion and lower Tre, mean skin temperature, and mean body temperature for the first 24, 14, and 16 min of exercise, respectively. Body heat storage rates differed significantly for LBI and WBI during immersion and exercise, although no net differences were observed between conditions. For WBI, metabolic heat production and heart rate were significantly higher during immersion but not during exercise. Thermal sensation was significantly lower (felt colder) and thermal discomfort was significantly higher (less comfortable) for WBI during immersion and exercise. In conclusion, WBI and LBI attenuated Tre increases during submaximal exercise and produced similar net heat storage over the protocol. LBI minimized metabolic increases and negative perceptual effects associated with WBI.

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