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Journal of Athletic Training 2009To critically assess original research addressing the effect of creatine supplementation on exercise heat tolerance and hydration status. (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To critically assess original research addressing the effect of creatine supplementation on exercise heat tolerance and hydration status.
DATA SOURCES
We searched the electronic databases PubMed, Scopus, Web of Science, SPORTDiscus, and Rehabilitation & Physical Medicine, without date limitations, for the following key words: creatine, exercise, thermoregulation, dehydration, hyperthermia, heat tolerance, exertional heat illnesses, and renal function. Our goal was to identify randomized clinical trials investigating the effect of creatine supplementation on hydration status and thermoregulation. Citations from related articles also were identified and retrieved.
DATA SYNTHESIS
Original research was reviewed using the Physiotherapy Evidence Database (PEDro) Scale. One author initially screened all articles. Fifteen of 95 articles examined the effects of creatine on thermoregulation or hydration status (or both). Two independent reviewers then reviewed these articles. Ten studies were selected on the basis of inclusion and exclusion criteria. The PEDro scores for the 10 studies ranged from 7 to 10 points (maximum possible score = 10 points).
CONCLUSIONS
No evidence supports the concept that creatine supplementation either hinders the body's ability to dissipate heat or negatively affects the athlete's body fluid balance. Controlled experimental trials of athletes exercising in the heat resulted in no adverse effects from creatine supplementation at recommended dosages.
Topics: Body Temperature Regulation; Creatine; Dehydration; Dietary Supplements; Exercise; Exercise Tolerance; Female; Fever; Hot Temperature; Humans; Male; Oxygen Consumption; Reference Values; Risk Factors; Sensitivity and Specificity; Water-Electrolyte Balance
PubMed: 19295968
DOI: 10.4085/1062-6050-44.2.215 -
Proceedings. Biological Sciences Aug 2022Performance benefits of stable, warm muscles are believed to be important for the evolution of endothermy in mammals, birds and flying insects. However, thermal...
Performance benefits of stable, warm muscles are believed to be important for the evolution of endothermy in mammals, birds and flying insects. However, thermal performance curves have never been measured for a free-flying endotherm, as it is challenging to vary body temperatures of these animals, and maximal flight performance is difficult to elicit. We varied air temperatures and gas densities to manipulate thoracic temperatures of flying honeybees from 29°C to 44°C, with low air densities used to increase flight metabolic rates to maximal values. Honeybees showed a clear thermal performance curve with an optimal temperature of 39°C. Maximal flight metabolic rates increased by approximately 2% per 1°C increase in thoracic temperature at suboptimal thoracic temperatures, but decreased approximately 5% per 1°C increase as the bees continued to heat up. This study provides the first quantification of the maximal metabolic performance benefit of thermoregulation in an endotherm. These data directly support aerobic capacity models for benefits of thermoregulation in honeybees, and suggest that improved aerobic capacity probably contributes to the multiple origins of endothermic heterothermy in bees and other insects.
Topics: Animals; Bees; Body Temperature; Body Temperature Regulation; Flight, Animal; Insecta; Mammals; Temperature
PubMed: 35975442
DOI: 10.1098/rspb.2022.0298 -
Journal of Thermal Biology Apr 2022Athletes with spinal cord injury (SCI) have difficulties in maintaining thermal homeostasis during exercise due to their lower sweat capacity and skin vasodilation. Skin... (Review)
Review
BACKGROUND
Athletes with spinal cord injury (SCI) have difficulties in maintaining thermal homeostasis during exercise due to their lower sweat capacity and skin vasodilation. Skin temperature (Tsk) assessment, as opposed to core temperature, has become more widely accepted due to its non-invasive nature. The aims of this systematic review was to collate research studies that measured Tsk of individuals with SCI during or after exercise, study their Tsk response, taking into account the method employed, the environmental and exercise conditions, and to identify the different cooling strategies and their effect during exercise.
METHODS
Pubmed, Web of Science and Scopus databases were searched to identify the articles published since year 2000. Two reviewers working independently extracted data and assessed the quality of the articles included. If they disagreed, a third reviewer was consulted. ROBINS-I scale was used to assess the quality of the articles, and the review has been conducted in agreement with PRISMA guidelines.
RESULTS
Twenty studies were included in this review. 84% of them presented moderate, serious or critical risk of bias. The entire of the studies assessed Tsk during exercise, but only seven studies measured it during rest or after exercise. Eighteen studies used contact thermometry to assess Tsk and the two remaining studies employed non-contact techniques. Seven studies were conducted in warm conditions (>31.5°C) and the remaining studies in moderate conditions (10°C to 26.6°C). According to cooling strategies, ice vests and water spray are effective in reducing Tsk and decreasing the risk of heat stroke.
CONCLUSIONS
The 90% of the studies applied contact thermometry and due to their effect in the data assessed, it is necessary more research into the SCI population using infrared thermography due to its differences in characteristics, methodology, and applications. The methodological differences among studies make difficult to perform a meta-analysis.
Topics: Body Temperature; Body Temperature Regulation; Exercise; Hot Temperature; Humans; Skin Temperature; Spinal Cord Injuries; Thermometry
PubMed: 35393040
DOI: 10.1016/j.jtherbio.2021.103146 -
International Journal of Sports... Nov 2022To continuously measure body core temperature (Tc) throughout a mass-participation ultramarathon in subelite recreational runners to quantify Tc magnitude and the...
PURPOSE
To continuously measure body core temperature (Tc) throughout a mass-participation ultramarathon in subelite recreational runners to quantify Tc magnitude and the influence of aerobic fitness and body fat.
METHODS
Twenty-three participants (19 men and 4 women; age 45 [9] y; body mass 72.0 [9.3] kg; body fat 26% [6%]; peak oxygen uptake 50 [6] mL·kg-1·min-1) had gastrointestinal temperature measured during an 89-km ultramarathon. Prerace-to-postrace changes in body mass, plasma sodium, and fluid and food recall quantified body water balance.
RESULTS
In maximal environmental conditions of 26.3 °C and 53% humidity, 21 of the 23 participants finished in 10:28 (01:10) h:min while replacing 49% (27%) of sweat losses, maintaining plasma sodium (140 [3] mmol·L-1), and dehydrating by 4.1% (1.3%). Mean maximum Tc was 39.0 (0.5) (range 38.2-40.1 °C) with 90% of race duration ≤39.0 °C. Mean maximum ΔTc was 1.9 (0.9) (0.9-2.7 °C) with 95% of race duration ≤2.0 °C. Over 0 to 45 km, associations between ΔTc and peak oxygen uptake (positive) and body fat (negative) were observed. Over 58 to 89 km, associations between Tc and peak oxygen uptake (negative) and body fat (positive) were observed.
CONCLUSIONS
Modest Tc responses were observed in recreational ultramarathon runners. Runners with higher levels of aerobic fitness and lower levels of body fat demonstrated the greatest changes in Tc during the first half of the race. Conversely, runners with lower levels of aerobic fitness and higher levels of body fat demonstrated the greatest absolute Tc in the final third of the race.
Topics: Male; Humans; Female; Middle Aged; Running; Body Temperature Regulation; Humidity; Sodium; Oxygen
PubMed: 36070861
DOI: 10.1123/ijspp.2022-0043 -
Scandinavian Journal of Work,... 1989The need for high-performance protective clothing systems in space, polar, and underwater operations and in industrial environments has stimulated research in clothing... (Review)
Review
The need for high-performance protective clothing systems in space, polar, and underwater operations and in industrial environments has stimulated research in clothing physiology. New, sophisticated measurement methods, some of which are going to be international standards, have facilitated this research. Measurements with subjects have validated manikin data, but have also provided information about the dynamic character and the individual variability of thermal properties of clothing under conditions encountered in the field. Manikin measurements of the basic thermal properties of clothing (insulation and evaporative resistance) have to be corrected to apply to the user situation, due to the effects of wind, posture, body movement, and moisture absorption. Evaporative heat transfer is better defined and should be incorporated in heat exchange models and thermal indices. Important aspects of clothing physiology remain to be investigated.
Topics: Body Temperature Regulation; Forecasting; Humans; Manikins; Protective Clothing; Ventilation
PubMed: 2692141
DOI: No ID Found -
European Journal of Sport Science Mar 2022The purpose of this study was to compare the efficacy of four cooling interventions used for reducing physiological and perceptual strain and improving exercise...
The purpose of this study was to compare the efficacy of four cooling interventions used for reducing physiological and perceptual strain and improving exercise performance during outdoor match-play tennis in the heat. Eight competitive tennis players played four counter-balanced simulated outdoor matches in the heat (WBGT: 28.4-32.5°C) at 24- or 48-h intervals. Each match comprised 3 sets for which the "no-ad" rule was applied to limit duration variability. Players underwent the following cooling interventions: ad libitum fluid ingestion (CON), ad libitum fluid ingestion and ice vest (VEST), total ingestion of approximately 1000 g ice slurry and ice vest (Combined: BINE), or total ingestion of approximately 400 g ice slurry and ice vest (Low-combined: L-BINE). Gastrointestinal temperature was lower in the BINE and the L-BINE trials than in the CON trial at the set-break of set 1, and these differences in gastrointestinal temperature persisted throughout the remainder of the match ( < 0.05). The ratio of moderate-high intensity activity (≥10 km/h) in set 3 was significantly higher in the L-BINE trial than that in the BINE trial ( < 0.05). In the CON and BINE trials, high intensity activity was significantly lower in set 3 compared with set 1 and 2, respectively. Cooling by optimal ice slurry ingestion and ice vest may be a more effective strategy in mitigating the development of heat strain during outdoor match-play tennis in the heat. Cooling by optimal ice slurry ingestion and ice vest may be a more effective strategy in mitigating the development of heat strain during outdoor match-play tennis in the heat.Ingesting of large amounts ice slurry may be caused the bloating and stomach discomfort, in turn declined in the ratio of moderate-high intensity activity in the second half of match-play tennis in hot outdoor environments.Future studies should not only utilize match characteristics, but also measure on-court tennis specific performance.
Topics: Body Temperature Regulation; Cold Temperature; Exercise; Hot Temperature; Humans; Tennis
PubMed: 33393422
DOI: 10.1080/17461391.2020.1870160 -
Jornal de Pediatria 2020To verify the thermoregulatory and perceptual responses of obese and lean girls, either fit or unfit, exercising in the heat at a similar rate of metabolic heat...
OBJECTIVE
To verify the thermoregulatory and perceptual responses of obese and lean girls, either fit or unfit, exercising in the heat at a similar rate of metabolic heat production per unit body mass.
METHODS
A total of 34 pubescent girls were allocated in four groups: 12 obese fit, 9 obese unfit, 5 lean fit, and 8 lean unfit. The obese groups (13.2±1.4 years, 40.5%±5.8% fat by DXA) differed in their aerobic fitness (V˙O 76.0±8.1 vs. 56.6±5.8mL.kgmusclemass.min), as well as the lean groups (13.1±1.6 years, 24.0%±4.8% fat) (V˙O 74.5±2.9 vs. 56.2±5.0mL.kgmuscle massmin). Girls cycled two bouts of 25min with a 10min rest in between, at ∼5.4W.kg in the heat (36°C and 40% relative humidity) and they were kept euhydrated. Rectal and skin temperatures and heart rate were measured every 5min. Perceptual responses were evaluated throughout the exercise.
RESULTS
Initial rectal temperature was higher in the obese subjects compared to the lean subjects (37.5±0.3 and 37.2±0.3°C). No difference was observed among the girls whom were obese (eight fit or unfit) and lean (also fit or unfit) throughout the exercise in rectal temperature (37.6±0.2, 37.5±0.3, 37.5±0.3, 37.4±0.3°C, respectively), skin temperature (34.8±0.8, 35.1±1.0, 34.4±0.9, 35.2±0.9°C), and heart rate (128±18; 118±12, 130±16, 119±16beatsmin). No differences were observed in perceptual responses among groups.
CONCLUSION
Regardless of the adiposity or aerobic fitness, pubescent girls had similar thermoregulatory and perceptual responses while cycling in the heat at similar metabolic heat production.
Topics: Adolescent; Body Temperature Regulation; Child; Exercise; Female; Hot Temperature; Humans; Obesity; Thermogenesis
PubMed: 31005547
DOI: 10.1016/j.jped.2018.12.011 -
Journal of Clinical Sleep Medicine :... Dec 2014Previous studies have associated restless legs syndrome (RLS) with peripheral hypoxia and impaired thermoregulation in the lower extremities. We performed long-term...
STUDY OBJECTIVES
Previous studies have associated restless legs syndrome (RLS) with peripheral hypoxia and impaired thermoregulation in the lower extremities. We performed long-term monitoring of skin temperatures in order to investigate whether these findings could be explained by reduced blood flow to the peripheral tissues.
METHODS
96-hour continuous measurements of skin temperature were performed both in the distal and proximal parts of the body of 15 patients with RLS and 14 healthy controls. During the recording, the patients participated in suggested immobilization tests both with and without pramipexole medication.
RESULTS
We found no baseline differences in distal or proximal skin temperature between patients and controls in daytime or during immobilization. However, pramipexole significantly increased distal skin temperature in the patient group during immobilization (31.1°C vs. 32.9°C, p < 0.05). Daytime temperatures were not affected by therapy or disease status.
CONCLUSIONS
The data suggest that patients with RLS and healthy controls have similar blood flow to the peripheral skin tissue. Pramipexole, however, alters thermoregulation and the previous studies might have been biased by medication. Dopaminergic medication is a major confounding factor when assessing peripheral phenomena in RLS and should be controlled for in the future studies.
Topics: Benzothiazoles; Body Temperature Regulation; Dopamine Agonists; Female; Humans; Male; Middle Aged; Polysomnography; Pramipexole; Restless Legs Syndrome; Severity of Illness Index; Skin Temperature
PubMed: 25325594
DOI: 10.5664/jcsm.4290 -
Insect Science Feb 2023Physiological thermotolerance and behavioral thermoregulation are central to seasonal cold adaptation in ectothermic organisms. For species with enhanced mobility,...
Physiological thermotolerance and behavioral thermoregulation are central to seasonal cold adaptation in ectothermic organisms. For species with enhanced mobility, behavioral responses may be of greater importance in the cold stress response. Employing the carabid beetles as a study organism, the current study compared physiological thermotolerance and behavioral thermoregulation in carabid species inhabiting cereal fields in different landscape contexts, from fine grain heterogeneous "complex" landscapes to homogenous "simple" landscapes. Physiological thermotolerance was determined via measurement of the CT and chill coma temperature. Behavioral responses to cold temperature exposure were determined employing a purpose built arena, and thoracic temperature measured to estimate the efficacy of the behavior as a form of behavioral thermoregulation. Results revealed an influence of landscape composition on the cold tolerance of carabid beetles, although species differed in their sensitivity to landscape intensification. A reduced effect of landscape on the thermotolerance of larger carabid beetles was observed, thought to be the consequence of greater mobility preventing local acclimation to microclimatic variation along the landscape intensification gradient. Investigation into behavioral thermoregulation of the 3 largest species revealed burrowing behavior to be the main behavioral response to cold stress, acting to significantly raise carabid body temperature. This finding highlights the importance of behavioral thermoregulation as a strategy to evade cold stress. The use of behavioral thermoregulation may negate the need to invest in physiological thermotolerance, further offering explanation for the lack of landscape effect on the physiological thermotolerance of larger carabids.
Topics: Animals; Thermotolerance; Coleoptera; Acclimatization; Body Temperature Regulation; Temperature
PubMed: 35438840
DOI: 10.1111/1744-7917.13044 -
Scientific Reports Apr 2021Temperature control is a process that is used by biological systems to maintain a stable internal state for survival. People have an individually variable physiological...
Temperature control is a process that is used by biological systems to maintain a stable internal state for survival. People have an individually variable physiological temperature of about 36.6 °C, which can be modified by many undesirable factors. Based on an analysis of a time series of extracellular ionic fluxes that were obtained using the non-invasive solute-semiconductor interface technique, I show that this extremely specific (critical) temperature is encoded by a local minimum in the dynamic entropy of an isolated drop of human blood. Moreover, a dynamic zeroth-order normal fluid/"superfluid" nonequilibrium phase transition, which was reflected by a spontaneous symmetry breaking that occurred in the phase space, was revealed. The critical scaling of the dynamic measures for the covariates such as the spectral signature and Lyapunov exponent was also determined.
Topics: Blood; Blood Physiological Phenomena; Body Temperature Regulation; Entropy; Hemodynamics; Humans; Phase Transition; Temperature
PubMed: 33828179
DOI: 10.1038/s41598-021-87212-z