scholarly journals Impact of muscle injury and accompanying inflammatory response on thermoregulation during exercise in the heat

2000 ◽  
Vol 89 (3) ◽  
pp. 1123-1130 ◽  
Author(s):  
Scott J. Montain ◽  
William A. Latzka ◽  
Michael N. Sawka
Keyword(s):  
Creatine Kinase ◽  
Heat Stress ◽  
Core Temperature ◽  
Interleukin 6 ◽  
Muscle Injury ◽  
Treadmill Exercise ◽  
Inflammatory Responses ◽  
Thermal Strain ◽  
Upper Body ◽  
Body Core Temperature

This study examined whether muscle injury and the accompanying inflammatory responses alter thermoregulation during subsequent exercise-heat stress. Sixteen subjects performed 50 min of treadmill exercise (45–50% maximal O2 consumption) in a hot room (40°C, 20% relative humidity) before and at select times after eccentric upper body (UBE) and/or eccentric lower body (LBE) exercise. In experiment 1, eight subjects performed treadmill exercise before and 6, 25, and 30 h after UBE and then 6, 25, and 30 h after LBE. In experiment 2, eight subjects performed treadmill exercise before and 2, 7, and 26 h after LBE only. UBE and LBE produced marked soreness and significantly elevated creatine kinase levels ( P < 0.05), but only LBE increased ( P < 0.05) interleukin-6 levels. In experiment 1, core temperatures before and during exercise-heat stress were similar for control and after UBE, but some evidence for higher core temperatures was found after LBE. In experiment 2, core temperatures during exercise-heat stress were 0.2–0.3°C ( P < 0.05) above control values at 2 and 7 h after LBE. The added thermal strain after LBE ( P < 0.05) was associated with higher metabolic rate ( r = 0.70 and 0.68 at 2 and 6–7 h, respectively) but was not related ( P > 0.05) to muscle soreness ( r = 0.47 at 6–7 h), plasma interleukin-6 ( r = 0.35 at 6–7 h), or peak creatine kinase levels ( r = 0.22). Local sweating responses (threshold core temperature and slope) were not altered by UBE or LBE. The results suggest that profuse muscle injury can increase body core temperature during exercise-heat stress and that the added heat storage cannot be attributed solely to increased heat production.

Cooling During Endurance Cycling in the Heat: Blunted Core Temperature but Not Inflammatory Responses

2020 ◽  
pp. 1-6
Author(s):  
Sebastian Keller ◽  
Simon Kohne ◽  
Hannah L. Notbohm ◽  
Wilhelm Bloch ◽  
Moritz Schumann
Keyword(s):  
Blood Lactate ◽  
Interleukin 6 ◽  
Inflammatory Responses ◽  
Core Body Temperature ◽  
Thermal Strain ◽  
Reactive Oxygen ◽  
Metabolic Responses ◽  
Peak Power Output ◽  
Nitrogen Species ◽  
Endurance Cycling

Purpose: This study assessed the effects of cooling during endurance cycling (percooling) on changes in core body temperature (Tcore), inflammatory, and metabolic responses. Methods: A total of 12 male cyclists (peak oxygen uptake 60 [4] mL·kg−1·min−1) completed a 60-minute constant workload trial (55% of peak power output and ambient temperature 30.4°C [0.6°C]) in a randomized order both with (ICE) and without (CON) an ice vest. An ingestible capsule was used to measure Tcore. Blood samples were collected immediately before and after each trial to determine concentrations of blood lactate, serum cortisol, interleukin-6, and reactive oxygen and nitrogen species. Results: Tcore increased statistically (P < .001) both in CON (7.0% [1.4%], effect size [ES] = 6.3) and ICE (5.1% [1.1%], ES = 5.7). The increase in CON was statistically larger compared with ICE (P = .006, ES = 1.4). Concentrations of blood lactate (CON: 163% [63%], ES = 1.3; ICE: 149% [91%], ES = 1.3), cortisol (CON: 138% [123%], ES = 1.7; ICE: 81% [102%], ES = 1.0), and interleukin-6 (CON: 661% [324%], ES = 2.1; ICE: 624% [368%], ES = 1.2) statistically increased in both conditions (P < .01) to a similar extent. In addition, reactive oxygen and nitrogen species statistically decreased in both conditions (CON: −19.2% [14.9%], P = .002, ES = 0.9; ICE: −15.1% [16.5%], P = .02, ES = 0.9). No correlations were found between the changes of Tcore and blood parameters across the conditions. Conclusions: Despite attenuated Tcore, similar inflammatory and metabolic responses were observed. Our findings suggest percooling to be a promising strategy to attenuate thermal strain without compromising physiological function.

Temporal Thermometry Fails to Track Body Core Temperature during Heat Stress

2007 ◽  
Vol 39 (7) ◽  
pp. 1029-1035 ◽  
Author(s):  
DAVID A. LOW ◽  
ALBERT VU ◽  
MARILEE BROWN ◽  
SCOTT L. DAVIS ◽  
DAVID M. KELLER ◽  
...  
Keyword(s):  
Heat Stress ◽  
Core Temperature ◽  
Body Core Temperature ◽  
Body Core

scholarly journals Exercise under heat stress: thermoregulation, hydration, performance implications and mitigation strategies

2021 ◽  
Author(s):  
Julien D. Periard ◽  
Thijs M.H. Eijsvogels ◽  
Hein A.M. Daanen
Keyword(s):  
Heat Stress ◽  
Exercise Performance ◽  
Thermal Strain ◽  
Mitigation Strategies ◽  
Body Core Temperature ◽  
Aerobic Performance ◽  
Future Research ◽  
Hydration Status ◽  
Fatigue Development ◽  
The Impact

A rise in body core temperature and loss of body water via sweating are natural consequences of prolonged exercise in the heat. This review provides a comprehensive and integrative overview of how the human body responds to exercise under heat stress and the countermeasures that can be adopted to enhance aerobic performance under such environmental conditions. The fundamental concepts and physiological processes associated with thermoregulation and fluid balance are initially described, followed by a summary of methods to determine thermal strain and hydration status. An outline is provided on how exercise-heat stress disrupts these homeostatic processes, leading to hyperthermia, hypohydration, sodium disturbances and in some cases exertional heat illness. The impact of heat stress on human performance is also examined, including the underlying physiological mechanisms that mediate the impairment of exercise performance. Similarly, the influence of hydration status on performance in the heat and how systemic and peripheral hemodynamic adjustments contribute to fatigue development is elucidated. This review also discusses strategies to mitigate the effects of hyperthermia and hypohydration on exercise performance in the heat, by examining the benefits of heat acclimation, cooling strategies and hyperhydration. Finally, contemporary controversies are summarized and future research directions provided.

Keeping a Cool Head

Physiology ◽  
1986 ◽  
Vol 1 (2) ◽  
pp. 41-44 ◽  
Author(s):  
M Cabanac
Keyword(s):  
Heat Stress ◽  
Core Temperature ◽  
Heat Exchangers ◽  
The Body ◽  
Body Core Temperature ◽  
Mammalian Brain ◽  
Poor Tolerance ◽  
Selective Cooling ◽  
Body Core ◽  
The Brain

The mammalian brain has poor tolerance to increased temperature. However, when body core temperature rises during exercise or heat stress, the temperature of the brain can remain at a lower level, somewhat independent of the rest of the body. In several mammals the cooling of the brain is related to anatomically well-defined countercurrent heat exchangers. Humans lack these distinct anatomic structures, but significant cooling of the brain can nevertheless occur. Such selective cooling of the brain may have important medical implicantions.

scholarly journals Local cooling during hot water immersion improves perceptions without inhibiting the acute interleukin-6 response

2021 ◽  
Author(s):  
R. G. Mansfield ◽  
S. P. Hoekstra ◽  
J. J. Bill ◽  
Christof A. Leicht
Keyword(s):  
Thermal Comfort ◽  
Interleukin 6 ◽  
Water Immersion ◽  
Hot Water ◽  
Upper Body ◽  
Healthy Male ◽  
Local Cooling ◽  
Blood Samples ◽  
Body Cooling ◽  
Hot Water Immersion

Abstract Purpose Passive elevation of body temperature can induce an acute inflammatory response that has been proposed to be beneficial; however, it can be perceived as uncomfortable. Here, we investigate whether local cooling of the upper body during hot water immersion can improve perception without inhibiting the interleukin-6 (IL-6) response. Methods Nine healthy male participants (age: 22 ± 1 years, body mass: 83.4 ± 9.4 kg) were immersed up to the waist for three 60-min water immersion conditions: 42 °C hot water immersion (HWI), 42 °C HWI with simultaneous upper-body cooling using a fan (FAN), and 36 °C thermoneutral water immersion (CON). Blood samples to determine IL-6 plasma concentration were collected pre- and post-water immersion; basic affect and thermal comfort were assessed throughout the intervention. Results Plasma IL-6 concentration was higher for HWI and FAN when compared with CON (P < 0.01) and did not differ between HWI and FAN (P = 0.22; pre to post, HWI: 1.0 ± 0.6 to 1.5 ± 0.7 pg·ml−1, FAN: 0.7 ± 0.5 to 1.1 ± 0.5 pg·ml−1, CON: 0.5 ± 0.2 to 0.5 ± 0.2 pg·ml−1). At the end of immersion, basic affect was lowest for HWI (HWI: − 1.8 ± 2.0, FAN: 0.2 ± 1.6, CON 1.0 ± 2.1, P < 0.02); thermal comfort for HWI was in the uncomfortable range (3.0 ± 1.0, P < 0.01 when compared with FAN and CON), whereas FAN (0.7 ± 0.7) and CON (-0.2 ± 0.7) were in the comfortable range. Conclusion Local cooling of the upper body during hot water immersion improves basic affect and thermal comfort without inhibiting the acute IL-6 response.

scholarly journals Evaluation of Three Formulations of Essential Oils in Broiler Chickens under Cyclic Heat Stress

Animals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 1084
Author(s):  
Jared Ruff ◽  
Guillermo Tellez ◽  
Aaron J. Forga ◽  
Roberto Señas-Cuesta ◽  
Christine N. Vuong ◽  
...  
Keyword(s):  
Heat Stress ◽  
Essential Oils ◽  
Broiler Chickens ◽  
Bone Mineralization ◽  
Body Core Temperature ◽  
Control Group ◽  
Group 4 ◽  
Body Core ◽  
Cyclic Heat ◽  
Group 2

The objective of the present research was to assess the dietary supplementation of three formulations of essential oils (EO) in chickens under heat stress (HS). Day-of-hatch Cobb 500 chicks (n = 500) were randomly distributed into four groups: 1. HS control + control diets; 2. HS + control diets supplemented with 37 ppm EO of Lippia origanoides (LO); 3. HS + control diets supplemented with 45 ppm LO + 45 ppm EO of Rosmarinus officinalis (RO) + 300 ppm red beetroot; 4. HS + 45 ppm LO + 45 ppm RO + 300 ppm natural betaine. Chickens that received the EO showed significant (p < 0.05) improvement on BW, BWG, FI, and FCR compared to control HS chickens. Average body core temperature in group 3 and group 4 was significantly (p < 0.05) reduced compared with the HS control group and group 2. Experimental groups showed a significant reduction in FITC-d at 42 days, a significant increase in SOD at both days but a significant reduction of IFN-γ and IgA compared with HS control (p < 0.05). Bone mineralization was significantly improved by EO treatments (p < 0.05). Together these data suggest that supplemental dietary EO may reduce the harmful effects of HS.

The recommended Threshold Limit Values for heat exposure fail to maintain body core temperature within safe limits in older working adults

2017 ◽  
Vol 14 (9) ◽  
pp. 703-711 ◽  
Author(s):  
Dallon T. Lamarche ◽  
Robert D. Meade ◽  
Andrew W. D'Souza ◽  
Andreas D. Flouris ◽  
Stephen G. Hardcastle ◽  
...  
Keyword(s):  
Core Temperature ◽  
Heat Exposure ◽  
Body Core Temperature ◽  
Limit Values ◽  
Threshold Limit Values ◽  
Working Adults ◽  
Threshold Limit ◽  
Body Core ◽  
Safe Limits
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