Top PDF Alleviating Heat Strain During Exercise: Hand Cooling and Thermoregulation

Alleviating Heat Strain During Exercise: Hand Cooling and Thermoregulation

Alleviating Heat Strain During Exercise: Hand Cooling and Thermoregulation

populations began to formalise a way of working that would eventually form the basis of farming. The abundance of food and water is intrinsically related to seasonal environmental conditions, and for societies that understood this link, commerce and economy developed, and civilisations prospered. Successful civilisations understood how temperature and seasonal variations influenced commodities such as livestock and grains. For those civilisations with developed economies, day-to-day life was no longer a struggle to survive because of poor energy intake, but instead, a struggle to avoid illness and disease. From these demands, basic forms of medicinal practice emerged. Early schools of medicine, with divine origins, linked temperature to illness and disease. One of the oldest forms of medical practice, Ayurveda, treats patients based on body temperature [17]. Ayurvedic medicine (Ayur - life, Veda - science) (c100BCE), which is still practised today, teaches that an imbalance in Pitta Dosha, a ‘life force’ that controls body heat is balanced by eating cool foods and massaging with cool oils. Empedocles (c490-430BCE) is credited as being the originator of the theory of the four classical elements of life; earth, water, air and fire [18], all of which had different characteristics and accordingly, temperature. Hippocrates (c460-360 BCE) and then Galen (c129-216 AD) sought to balance the “four humours”, in their medical practice, and 'the cure for one which has been heated is chilling´ has been transcribed from Ancient Greek and Roman texts.
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Alleviating Heat Strain During Exercise: Hand Cooling and Thermoregulation

Alleviating Heat Strain During Exercise: Hand Cooling and Thermoregulation

2.5.2 Perceptual responses Flouris and Schlader [149] suggested that thermal perception is an important mediator of behavioural thermoregulation that integrates with RPE in its role as the predominant controller of exercise intensity. We found that RPE and thermal perception were improved by cooling during fixed-intensity exercise and is a key finding from our analysis. Prior to increases in core temperature, self-selected intensity of exercise is likely mediated by thermal perception and its influence on RPE, whereas when core and skin temperature are elevated cardiovascular strain is a key RPE input [149]. Studies included in the present meta-analysis used neck cooling, ice slurry and fluid ingestion. Cooling the neck during heat exposure elicits feelings of thermal comfort at rest [81], a finding extended to 2 [167, 236] of 3 neck cooling during exercise studies. We found an unclear effect for one study [168]; the reason for this is unknown as the neck cooling collar was the same and participants and environmental conditions were similar in all three investigations. The study, however, was designed to investigate time to exhaustion and final core temperature was >39 °C, therefore cardiovascular strain might have been the key RPE mediator rather than thermal perception, however, it is worth noting that RPE was similar between conditions. There was also a clear beneficial effect of ice slurry ingestion on thermal perception in one study [233] but not in another [164]. These differences might be attributed to the study design, specifically, a beneficial effect of set-planned [233] rather than ad libitum [164] ingestion of slurry. Lee et al. [235] reported similar between-trial responses for thermal perception (400 ml of 10°C fluid versus 37 °C fluid ingested at 15 min intervals), although the mean ambient temperature of 25.3 °C combined with an intensity of 50% V̇O 2max was among the least
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Lasting Effects of Exercise in Heat on Subsequent Exercise and Thermoregulation

Lasting Effects of Exercise in Heat on Subsequent Exercise and Thermoregulation

What are the benefits of the study? The proposed study will increase knowledge of the effects of heat acclimation on body cooling and thermoregulation. This may improve athletic performance in athletes and help medical professionals prevent heat related injuries. The results of this study may influence and encourage further education of health care providers regarding the importance of heat acclimation before intense exercise in hot environments. Your participation in this study may benefit the general population, by allowing researchers, athletic trainers and coaches better implement heat acclimation protocols to improve performance and mitigate the risk of exertional heat illnesses. Understanding how the body responds to long bouts of exercise-heat stress the following day is vital in preventing exertional heat illness. Exploring whether heat acclimation improves hand cooling effectiveness will enhance our utilization of this
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Heat Compressor for Adsorption Cooling

Heat Compressor for Adsorption Cooling

A cylindrically shaped solid adsorbent was selected for the simulation of heat compressor op­ eration. Heat compressors contain a heat exchanger, which in our case consisted of one or several copper tubes of equal dimensions, coated with a compact layer of an adsorbent, compact denoting a homoge­ neous, compressed layer of adsorbent particles. The diffusion between particles in such a layer can be assumed to be macroporous. However, the resistance to mass transfer in microporous diffusion is negli­ gible, i.e. for the adsorbate vapour there is no resis­ tance to mass transfer into the adsorbent particles. The temperatures in the condenser Tk and evapora­ tor T v were selected for numerical simulation of the entire adsorption cooling process. As presented in Figure 1, the heat compressor was virtually connected with two vessels required for the operation of the adsorption cooling device. The temperature and con­ centration fields along the heat exchanger were analysed and were therefore divided into several seg­ ments designated by index j. The division of heat exchanger segments to individual control volumes, for which local adsorption equilibriums were calcu­ lated (p, T, x), is presented in Figure 2. Simulation was performed only for the working couple zeolite WE894 - water.
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Effect of Agitation Work on Heat Transfer during Cooling in Oil ISORAPID 277HM

Effect of Agitation Work on Heat Transfer during Cooling in Oil ISORAPID 277HM

The article focuses on the issue of heat treatment. The cooling curves were obtained for Isorapid 277HM with an experimental way of temperature measuring and their statistical processing. Experimental method was consistent with the test normative ISO standard 9950 (Wolfson’s test). The cooling oil Isorapid 277HM was agitated with different agitation work and had a constant temperature of 50 °C. In the next part of this article the surface temperature depended combined heat transfers were calculated. The methodology was based on inverse heat transfer. The interpretation code was software ANSYS and ORIGIN.
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Ice Slurry and Cold Drink Reduces Exercise Induced Physiological Strain in the Heat

Ice Slurry and Cold Drink Reduces Exercise Induced Physiological Strain in the Heat

heat sink” compared to the cold drink. Moreover, changes in sweat rate are congruent to the findings in body mass loss throughout the exercise trials. These findings showed that body mass loss was significantly the lowest in the ICE (-0.28 ± 0.08 kg) compared to the COLD (-0.35 ± 0.09 kg) and RT (-0.48 ± 0.10 kg) trials. Coupled with the other findings, these data suggest that ice slurry ingestion best combats dehydration compared to other drink modalities by better balancing the fluid requirements associated with thermoregulation in the heat. Since heat stress in the human leads to increased sweating (to best counter the rise in core temperature), ice slurry acts as a surrogate approach to mitigate the rise in core temp, thus reducing the requirements of other physiological mechanisms (i.e. sweating).
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High thermoregulatory strain during competitive paratriathlon racing in the heat

High thermoregulatory strain during competitive paratriathlon racing in the heat

athletes reported experiencing symptoms of heat illness during the race, of which ten wore a 196. wetsuit[r]

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Hand and torso pre-cooling does not enhance subsequent high-intensity cycling or cognitive performance in heat

Hand and torso pre-cooling does not enhance subsequent high-intensity cycling or cognitive performance in heat

Table 2. Total Work (kJ) and Mean Power Output (MPO; Watts) recorded during the simulated cycling race protocol following a 30 min pre- cooling period using a cooling glove (CG), cooling jacket (CJ), cooling glove and jacket (CG+J) or no cooling (NC) (n=10). CG CJ CG+J NC Work MPO Work MPO Work MPO Work MPO

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Effects of Cooling During Exercise on Thermoregulatory Responses of Men With Paraplegia.

Effects of Cooling During Exercise on Thermoregulatory Responses of Men With Paraplegia.

Day 1: maximal exercise test. Physi- cal fitness (V ˙ O 2 max) and peak PO were determined using a maximal exercise test on an arm ergometer (Angio Cycle Ergometer, Lode, Groningen, the Nether- lands) at an ambient temperature of 19°C. During the maximal exercise test, participants started cycling at 10 W with an arm crank cycle frequency of 60 to 80 repetitions per minute. The workload was increased 10 W every minute until voluntary exhaustion. Continuous mea- surement of oxygen uptake and carbon dioxide output was performed using an automatic gas analyzer (Quark CPET, ver- sion 9.1b, COSMED, Rome, Italy). Peak oxygen uptake was calculated as the average oxygen uptake during the last 30 seconds of the test. Peak PO was defined as the workload at the highest intensity that the participant could maintain for at least 30 seconds. Heart rate was mea- sured continuously using a 12-lead electrocardiograph.
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Skeletal strain patterns in relation to exercise training during growth

Skeletal strain patterns in relation to exercise training during growth

Implicit in our use of in vivo strain gauge recordings to ‘map’ the functional distribution of strain within a bone and to characterize its loading history for a given exercise regimen is the assumption that a uniaxial (planar) state of strain exists at each of the recording sites on the bone’s surface. However, given that the actual state of strain within a local region of the bone (both at the bone’s surface and deeper within its cortex) is the result of multiaxial loading, the objective of strain-mediated bone modeling is more likely to involve a three-dimensional assessment of strain at a local cellular level. In addition, by focusing on peak strain magnitude, we ignore the time-varying nature of functional loading patterns. Using two-dimensional finite element models, Carter and his colleagues (Carter, 1987; Carter et al. 1987; Carter and Wong, 1988) have shown that the decomposition of strain energy density into hydrostratic versus shear strain densities predicts well the spatial and temporal ossification patterns within a fetal bone, in which regions of high shear strain stimulate the differentiation of cartilage into bone. In that strain energy density can be generalized throughout the whole of a bone (in constrast to the site-specific nature of strain magnitude), it is an attractive candidate for the load- related variable to which bone cells respond. A recent study that attempted to correlate patterns of strain energy density with a bone’s modeling response, however, found the correlation to be weak (Brown et al. 1990).
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During exercise in the heat, body temperature elevations

During exercise in the heat, body temperature elevations

Reductions in sweat rate and subsequently the potential for evaporative heat loss from the skin with cold fluid inges- tion are probably modulated by independent thermoreceptors residing in the abdominal area, since changes in sudomotor output are observed without any forerunning differences in core or skin temperatures (25). However, the dynamic response of local sweat rate (LSR) and any concomitant changes in skin blood flow (SkBF) have not yet been com- pared between thermoneutral fluid and ice slurry ingestion, and it is possible that thermosensory input from abdominal thermoreceptors is limited. From a practical perspective, it is also important that these comparisons are conducted in warm environmental conditions, since most physical activities that require a form of cooling are typically performed in such environments (33) and are similar to the ambient conditions used in previous ice slurry studies (2,35). Moreover, higher skin temperatures arising in hot climates may mitigate the re- ductions in local and whole-body sweat rates previously ob- served in a temperate environment (25).
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DEVELOPMENT OF A PERCEPTUAL HYPERTHERMIA INDEX TO EVALUATE HEAT STRAIN DURING TREADMILL EXERCISE. Michael Gallagher, Jr.

DEVELOPMENT OF A PERCEPTUAL HYPERTHERMIA INDEX TO EVALUATE HEAT STRAIN DURING TREADMILL EXERCISE. Michael Gallagher, Jr.

Maughan et al. 42 summarizes in their review that performance on physical and mental tasks are significantly reduced by heat stress and dehydration. This response is due to the additional stress imposed on the cardiovascular system that may be a detriment to the central nervous system. Cheung 14 described a fundamental problem with previous research that assessed brain activity during hyperthermia. They noted that few studies tracked the effect of thermal stress on cognitive and task performance impairments in the presence of concomitant changes in physiological and/or perceptual thermal strain. As part of their training, the Australian Defense Forces have been exposed to “debilitating” tropical environments that negatively impacts physiological performance. Hocking et al. 28 observed that in addition to these physiological detriments, thermal strain did not impact cognition of those military personnel. It was found that even through subjects experienced increased cardiovascular strain, the psychometric test batteries showed no significant performance detriments yet there was a marked difference in the electrical responses of the brain when thermally strained. Cheung 14 suggests that while cognitive impairment may be sensitive to thermal stress, it may also be negated or minimized by other compensatory mechanisms that limit performance degradation. This may help explain conflicting results among studies examining hyperthermia (and the resulting hypohydration) on cognitive function.
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Heating and Cooling With a Heat Pump

Heating and Cooling With a Heat Pump

There are two types of air-source heat pumps. The most common is the air-to-air heat pump. It extracts heat from the air and then transfers heat to either the inside or outside of your home depending on the season. The other type is the air-to-water heat pump, which is used in homes with hydronic heat distribution systems. During the heating season, the heat pump takes heat from the outside air and then transfers it to the water in the hydronic distribution system. If cooling is provided during the summer, the process is reversed: the heat pump extracts heat from the water in the home’s distribution system and "pumps" it outside to cool the house. These systems are rare, and many don’t provide cooling; therefore, most of the following discussion focuses on air-to-air systems. More recently, ductless mini-split heat pumps have been introduced to the Canadian market. They are ideal for retrofit in homes with hydronic or electric resistance base- board heating. They are wall-mounted, free-air delivery units that can be installed in individual rooms of a house. Up to eight separate indoor wall-mounted units can be served by one outdoor section.
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Exercise for rheumatoid arthritis of the hand

Exercise for rheumatoid arthritis of the hand

In 2004, Wessel conducted a narrative review of nine English-lan- guage only randomised and non-randomised studies published up to 2003, including four of the seven studies in this review (Wessel 2004). Wessel concluded that there was little evidence to support or refute hand exercise. Since this time only one other systematic review has been published (Bergstra 2014), which drew more posi- tive conclusions about the effectiveness of exercise on the RA hand. Bergstra 2014 included eight randomised and non-randomised studies and inferred that grip strength and function were consis- tently improved, but changes for range of motion were incon- sistent. The conclusions from our review differ slightly, showing moderate evidence for small beneficial effects on hand function, but little or no effect on grip strength in the medium and long term. Our review is the only review to include only randomised trials assessing the effectiveness of hand exercises in RA. No re- views prior to this have attempted a meta-analysis.
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Practical cooling strategies during continuous exercise in hot environments: a systematic review and meta-analysis

Practical cooling strategies during continuous exercise in hot environments: a systematic review and meta-analysis

scientists towards research that has high ecological validity and sound mechanistic underpinning. 5 Conclusion We found that practical cooling strategies administered during exercise before a self-paced endurance trial improve performance in hot environments, but not by decreasing core temperature as previously thought [ 18 ]. Instead we suggest that current methods improve performance by benefiting thermal perception and RPE, resulting in greater self-se- lected external intensities compared with a thermoneutral or no cooling trial, thus improving endurance performance. We encourage practitioners to explore the use of cold fluid, ice slurry ingestion and neck cooling for endurance performance enhancement after examining the thermal constraints of the environment. Future research should investigate a combi- nation of approaches to cooling during continuous exercise as well as additional sites, such as the hands, that have the potential to attenuate increases in body temperature.
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Practical cooling strategies during continuous exercise in hot environments: a systematic review and meta analysis

Practical cooling strategies during continuous exercise in hot environments: a systematic review and meta analysis

Initial electronic database searches were performed up to 10 March 2015 using MEDLINE, SPORTDiscus, Scopus and Physiotherapy Evidence Database (PEDro). The elec- tronic database search was updated on 17 May 2016. Medical subject headings (MeSH), database indexing terms, keywords and Boolean operators (AND/OR) were used in the search strategy. Terms were grouped into themes related to cooling, exercise and body temperature regulation. For SPORTDiscus, search terms included ‘cool*’, ‘cold*’, ‘cold temperature’, ‘cryotherapy’, ‘exer- cise’, ‘physical fitness’, ‘exercise therapy’, ‘physical exertion’, ‘sports’, ‘exercise movement techniques’, ‘core temperature’, ‘rectal or oesophageal or esophageal or int- est* or tympanic AND temperature’, ‘body temperature’, ‘body temperature regulation’, ‘thermosen*’, ‘thermor*’, ‘hypothermia’, ‘hyperthermia’. All searches were con- ducted by the same author (AR). Search results were col- lated using Endnote software (Thomson Reuters, New York), and duplicates were removed. The title and abstract of the remaining studies were screened for relevance (AR). Full texts of potentially appropriate studies were obtained and independently assessed for eligibility by two authors (AR/BR) according to the inclusion criteria. Reference lists and citations (via Google Scholar search) of manuscripts and relevant review articles were examined for potentially eligible studies (AR).
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Skeletal muscle metabolic gene response to carbohydrate feeding during exercise in the heat

Skeletal muscle metabolic gene response to carbohydrate feeding during exercise in the heat

since the P trial received no carbohydrate into the recov- ery period, it is quite possible that the greater fat oxida- tion during the later stages of exercise continued into recovery in the P trial and subsequently attenuated the UCP3 mRNA expression. This is supported by evidence that elevated circulating fatty acids are associated with the upregulation of skeletal muscle expression of UCP3 [14,41-43]. We do not have evidence of circulating free fatty acids (FFA) in the current study, but it is well established that fasted exercise in the absence of carbo- hydrate delivery elevates FFA compared to carbohydrate trials [44]. Although fat oxidation appears to coincide with UCP3 expression, the metabolic role of this protein in skeletal muscle remains unclear as it suggests a loss of exercise efficiency by uncoupling the proton gradient created in the electron transport chain from ATP syn- thesis. However, besides fat oxidation, UCP3 has been implicated as being important in the control of thermo- genesis and the regulation of oxidative stress [45]. The long term implications of the attenuation of UCP3 ex- pression following exercise with carbohydrate supple- mentation in this study and others has yet to be determined [14,43]. It is intriguing to think that lower UCP3 mRNA may play a role in previous evidence of the carbohydrate attenuating effect on fat oxidation with exercise training [44,46]. These studies demonstrated that low carbohydrate availability (fat adapted) resulted in greater rates of fat oxidation even when glycogen levels were restored with a day on a high carbohydrate diet. Our study and others have shown that UCP3 is the gene most consistently attenuated with the consumption of exogenous carbohydrate. How UCP3 expression is af- fected during longer periods of low carbohydrate
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Dynamics of cryogen deposition relative to heat extraction rate during cryogen spray cooling.

Dynamics of cryogen deposition relative to heat extraction rate during cryogen spray cooling.

same throughout the entire sprayed spot, (point 7 in section 4.1). We can speculate on possible reasons for the lateral inhomogeneity. In the center of the spray, the cooling by the narrow nozzle is similar to that by the wide nozzle during the first 40 ms. Possibly, these 40 ms represent the time it takes to build up a cryogen or ice/snow layer that starts acting as a thermal barrier after the 40 ms have elapsed. The features in the signal for the narrow nozzle at the periphery are more complex. We are currently setting up a phase Doppler particle analyzer (PDPA) system which will measure droplet size, density and velocity distributions at any point in the spray. This will probably help to explain lateral differences in the sprayed area as well.
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Thermoregulatory burden of elite sailing athletes during exercise in the heat: A pilot study.

Thermoregulatory burden of elite sailing athletes during exercise in the heat: A pilot study.

Moores University, Liverpool, UK ABSTRACT Exercising in a hot and humid environment increases core body temperature, which may limit exercise performance. The risk of exercise-induced hyperthermia and associated performance decrement in Olympic sailing athletes is largely unknown. Therefore, this study aimed to compare thermoregulatory responses and performance indicators of elite sailors in a cool versus hot and humid environment. Seven elite athletes from four different Olympic sailing classes (Laser, RS:X, Finn, 470) performed cycling and/or rowing exercise in a cool (18°C) and hot (33°C) environment, while core body temperature (T C ), skin temperature (T SK ), exercise performance (covered distance), and rating of perceived exertion were measured continuously. T C increased significantly more in the hot environment (37.6 ± 0.2°C to 39.1 ± 0.1°C) compared to the cool environment (37.5 ± 0.1° C to 38.5 ± 0.2°C; p = 0.002), but the increase in T C between conditions differed substantially within individuals (range: 0.3°C – 0.9°C). Exercise performance decreased by 6.2 ± 2.9% in the hot environment (p = 0.013, range: 2.3% –9.5%), but more importantly, exercise performance was strongly inversely related to peak T C (R = −0.78, p = 0.039). Rating of perceived exertion (cool: 14.2 ± 0.6; hot: 13.9 ± 1.2) and increase in T SK (cool: 0.5 ± 1.0°C; hot: 0.9 ± 0.3°C) did not differ between conditions (p = 0.59 and p = 0.36, respectively). To conclude, a larger increase in T C and substantial exercise performance decrement were observed in the hot versus cool environment. As a further matter, large inter-individual differences were observed across athletes with an inverse relationship between T C and exercise performance, which stresses the importance of appropriate and personalized interventions to reduce thermoregulatory burden of elite sailors during exercise in the heat.
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Cooling via one hand improves physical performance in heat-sensitive individuals with Multiple Sclerosis: A preliminary study

Cooling via one hand improves physical performance in heat-sensitive individuals with Multiple Sclerosis: A preliminary study

Each subject was equipped with a heart rate monitor prior to all trials. The stop criterion for all exercise trials was symptom exacerbation which included subjective fatigue and gait or posture deterioration. Baseline assessments of individual physical performance capacities were con- ducted on day 1. For this assessment the subject began walking on a level treadmill at 0.8 Km/hr (0.5 mi/hr). At three minute intervals the speed or slope of the treadmill was alternately increased. The speed was increased by 0.8 Km/hr increments up to a maximum speed of 5.6 Km/hr (3.5 mi/hr). The slope of the treadmill was increased by 1% increments. Once the treadmill speed reached 5.6 Km/ hr, only the slope was incrementally increased. For the subsequent experimental trials the speeds and slopes of the treadmill were adjusted to approximate 65% of the maximum work load achieved by the individual subject during his or her baseline trial. The workload for each sub- ject was kept constant for the pair of experimental trials. An experimental trial consisted of the subject walking on the treadmill at a predetermined speed and slope until a stop criterion was reached. Experimental trials were initi- ated not less than two days after the baseline assessment trial and separated by a minimum of two days and a max- imum of seven days. The subjects returned to the labora- tory at the same time of day for all of their trials. All subjects performed a minimum of two experimental tri- als, one without using the heat extraction device and one using the device. The daily experimental routine consisted of a fifteen min rest in a sitting position, a 3 min warm-up walk at 1.6 Km/min and 0% slope, the experimental trial, and 30 min of seated recovery. On days when cooling treatments were administered, the heat extraction device was donned prior to the onset of treadmill activity. The order of the treatments was randomized. A flip of a coin before the first of two paired trials determined treatment
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