Exercise-heat Stress Research Articles

Local cooling in wheelchair athletes during exercise-heat stress

Wheelchair athletes with spinal cord injuries (WA) face challenges to thermal homeostasis, including reduced cutaneous vasoaction and sweat production. The purpose of this study was to evaluate the efficacy of local cooling to reduce heat strain in WA. Six elite, endurance-trained male WA (33 +/- 3 yr, 64 +/- 4 kg) performed three strenuous exercise tests in a hot-humid environment (32.9 +/- 0.1 degrees C, 75 +/- 3% RH) by pushing a racing chair on a stationary roller (30 min, 16.5 km.h-1, 704-766 W metabolic heat) while wearing shorts and socks. The three treatments involved an ice-packet vest (V) (0.14 m2 of skin surface), a refrigerated headpiece (H) (0.16 m2), or no cooling (C) (control). The vest and headpiece offered potential cooling of 388 W and 266 W. Mean body heat storage for trials V (117 +/- 26 W), H (117 +/- 22 W), and C (164 +/- 40 W) were statistically similar, partly because V (117 +/- 47 W) and H (75 +/- 59 W) cooled inefficiently (30 and 28%, respectively). Repeated measure ANOVA indicated no significant between-treatment differences (P > 0.05) for any variable in trials V, H, and C. We concluded that local cooling during V and H was ineffective because heat storage decreased, but was not prevented.

Exercise heat stress in rats: performance and biochemical effects

Disturbed mental status (DMS) is the most obvious sign of exertional heatstroke in humans, and is one of the main complications of severe exercise heat-stress (SHS). The cause of exertional heat-stroke has been attributed to many factors such as thermoregulatory failure or impairment of muscular function. This investigation was designed to assess muscle energy metabolism in two groups of rats running at 34 °C. One group ( n = 17) stopped because of DMS (SHS rats), while the other group (n = 21) stopped because of mild or moderate exercise heat-stress (MHS rats). SHS rats ran longer and had a higher final rectal temperature ( Tre): 66.5 ± 4.2 °C vs 47.3 ± 3.8 °C, p <0.05 and 42.7 ± 0.12 °C vs42.2 ± 0.15 °C, p < 0.05, respectively. SHS rats also had a slower rate of change of Tre (0.054 ± 0.007 °C min−1 vs 0.072 ± 0.008 °C min−1) and a lower mean rate of dehydration: 0.065 ± 0.006 vs 0.084 ± 0.005% bodyweight min−1, p < 0.05. There were no significant differences between the two groups for skeletal muscle concentration of high energy phosphates and glycogen, but lactate was higher in SHS than in MHS rats: 25.0 ± 6.7 vs 11.8 ± 1.6 μmoles per mg protein respectively, p <0.05. These data suggest that DMS may be linked to Tre and that there is muscular functional impairment caused by SHS.

Influence of the timing of fluid ingestion on temperature regulation during exercise

The purpose of this investigation was to determine whether the timing of fluid ingestion affects thermoregulation during exercise-heat stress. On four occasions, seven endurance-trained cyclists [age 25 +/- 2 (SE) yr, body weight 70.5 +/- 3.3 kg, maximal O2 uptake (VO2max) 4.69 +/- 0.11 l/min] performed 140 min of cycle ergometer exercise at 62-66% of VO2max in a hot environment (33 degrees C dry bulb, 51% relative humidity, wind speed 2.5 m/s). The subjects drank 1,173 +/- 44 ml of a carbohydrate-electrolyte beverage after 0 min (D0), 40 min (D40), or 80 min (D80) of exercise or consumed the same total volume in small aliquots throughout exercise (DT). The exercise-heat stress resulted in calculated sweating rates of approximately 1,200 ml/h and a body weight loss of 2.9 +/- 0.1% after 140 min of exercise. After fluid intake in the D0, D40, and D80 trials, there was a time period (approximately 40 min) in which the increases in serum osmolality and sodium concentration and the reduction in blood volume were attenuated. During that same time period, there was an attenuated rise in esophageal temperature (Tes; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Physiological consequences of hypohydration

During exercise in the heat, sweat output often exceeds water intake, which results in a body water deficit or hypohydration. This water deficit occurs from both the intracellular and extracellular fluid compartments, and causes a hypertonic-hypovolemia of the blood. Aerobic exercise tasks are likely to be adversely affected by hypohydration; and the warmer the environment the greater the potential for performance decrements. Hypohydration causes greater heat storage and reduces one's ability to tolerate heat strain. The greater heat storage is mediated by reduced sweating rate (evaporative heat loss) and reduced skin blood flow (dry heat loss) for a given core temperature. Reductions of sweating rate and skin blood flow are most tightly coupled to blood hypertonicity and hypovolemia, respectively. In addition, hypovolemia and the displacement of blood to the skin make it difficult to maintain central venous pressure and thus an adequate cardiac output to simultaneously support metabolism and thermoregulation during exercise-heat stress.

Polycythemia and hydration: effects on thermoregulation and blood volume during exercise-heat stress.

We studied the effects of autologous erythrocyte infusion on thermoregulation and blood volume during exercise in the heat. Specifically, we wanted to determine whether heat-acclimated subjects, as well as hypohydrated subjects, would have a thermoregulatory advantage from acute polycythemia during exercise in the heat. Five heat-acclimated males attempted four heat stress tests (HSTs): two pre- and two postinfusion. Autologous erythrocyte infusion was accomplished with 500 ml of a NaCl-glucose-phosphate solution containing approximately 60% hematocrit. One HST, both pre- and postinfusion, was done while subjects were euhydrated, and one HST was done while subjects were hypohydrated (-5% of body wt). After 30 min of rest in a 20 degrees C antechamber, the HST consisted of a 120-min exposure (2 repeats of 15 min rest and 45 min walking) in a hot (35 degrees C, 45% relative humidity) environment. The findings concerning acute polycythemia in heat-acclimated subjects are summarized: 1) polycythemia increased (P less than 0.05) sweating rate and reduced (P less than 0.01) core temperature during exercise-heat stress for both euhydrated and hypohydrated subjects; 2) the erythrocyte infusion caused an increased (P less than 0.05) plasma volume and increased (P less than 0.01) blood volume; 3) the increased plasma volume was associated with an increased (P less than 0.05) total circulating protein mass; 4) the increased total circulating protein mass tended to better maintain plasma volume when hypohydrated; and 5) heat acclimation may increase extravascular protein mass. Therefore, it is concluded that erythrocyte infusion provides a thermoregulatory advantage during exercise in the heat for heat acclimated subjects when both euhydrated and hypohydrated.

Plasma hormonal responses at graded hypohydration levels during exercise-heat stress.

The effects of graded levels of hypohydration (3, 5, and 7% of body weight) on hormonal responses to exercise in the heat were examined in six heat-acclimated male volunteers. On the day following dehydration, subjects performed light (approximately 25% maximal O2 consumption, 1.03 1 X min-1) exercise in a hot (49 degrees C, 20% relative humidity) environment for four consecutive 25-min intervals interspaced by 10-min rests; blood was obtained before exercise and at approximately 10 min before completion of each exercise period. During euhydration, plasma cortisol (PC) levels manifested significant decrements over time (e.g., time 0, 14.2 micrograms X 100 ml-1 vs. time 2, 8.9 micrograms X 100 ml-1), probably related to its diurnal periodicity. However, during hypohydration, levels of PC were increased and correlated with hypohydration intensity (e.g., time 0, 0, 3, 5, and 7% hypohydration, 14.2, 16.5, 19.8, and 36.2 micrograms X 100 ml-1, respectively). Plasma renin activity (PRA) was increased significantly by hypohydration (e.g., time 0, euhydrated vs. 3%, 3.7 vs. 6.2 units) but was unaffected by exercise in the heat. Plasma aldosterone (ALD) levels were generally increased by exercise in the heat (e.g., time 0 vs. time 4, 3% hypohydration, 12.1 vs. 18.7 ng X 100 ml-1). Regression analysis illustrated that graded intensities of hypohydration were correlated with incremented PRA and ALD through 5% hypohydration. Conversely, PC was incrementally elevated through 7% hypohydration.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of Hydration Level and Body Fluids on Exercise Performance in the Heat

During exercise in the heat, sweat output often exceeds water intake, resulting in hypohydration, which is defined as a body fluid deficit. This fluid deficit is comprised of water loss from both the intracellular and extracellular fluid compartments. Hypohydration during exercise causes a greater heat storage and reduces endurance in comparison with euhydration levels. The greater heat storage is attributed to a decreased sweating rate (evaporative heat loss) as well as a decreased cutaneous blood flow (dry heat loss). These response decrements have been attributed to both plasma hyperosmolality and a plasma hypovolemia. Subject gender, acclimation state, and aerobic fitness do not alter the increased heat storage when hypohydrated. Hyperhydration, or body fluid excess, does not seem to provide a clear advantage during exercise-heat stress, but will delay the development of hypohydration.

A differential catecholamine response during prolonged exercise and passive heating.

Plasma catecholamines (Ca) increase over time during prolonged exercise at a constant work rate. Possible reasons for this include hypoglycemia, dehydration, increased perceived exertion, and rising body temperature. In an effort to ascertain the contribution of elevated core temperature on the plasma Ca response to prolonged exercise four trained men were studied under two thermal conditions during 45 min of bicycle exercise (approximately 60% Vo2max) and during passive heating. On one testing day each subject was heat-stressed during exercise wearing a nylon pullover shell and cotton pants, (heat stress treatment); on the second day fans were directed on the subjects exercising in a thermoneutral environment (fan treatment). The passive heating experiment was conducted in a hot water bath (41 degrees C). The exercise heat stress treatment produced a higher plasma norepinephrine (NE) concentration (P less than 0.05) in all subjects than the fan treatment. The plasma epinephrine (E) concentration was not significantly (P greater than 0.05) different during exercise in the heat stress treatment from that found during fan treatment. A rise in rectal temperature (Tre) during passive heating resulted in quantitatively small changes in plasma E and NE. The heat load combined with the exercise task produced an increase in plasma NE concentration greater than the sum of the values measured during exercise in the thermoneutral environment and passive heating. This suggested that the combination of stressors caused an augmentation of the sympathetic nervous system's response. Finally, the added heat load caused changes in plasma NE and little change in plasma E, suggesting a differential Ca response with heat stress.

Physiological responses of physically fit men and women to acclimation to humid heat.

ARTICLESPhysiological responses of physically fit men and women to acclimation to humid heatB. A. Avellini, E. Kamon, and J. T. KrajewskiB. A. Avellini, E. Kamon, and J. T. KrajewskiPublished Online:01 Aug 1980https://doi.org/10.1152/jappl.1980.49.2.254MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByExercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategiesJulien D. Périard, Thijs M. H. Eijsvogels, and Hein A. M. Daanen27 August 2021 | Physiological Reviews, Vol. 101, No. 4Thermoregulatory adaptations with progressive heat acclimation are predominantly evident in uncompensable, but not compensable, conditionsNicholas Ravanelli, Geoff Coombs, Pascal Imbeault, and Ollie Jay14 October 2019 | Journal of Applied Physiology, Vol. 127, No. 4Menstrual cycle phase does not modulate whole body heat loss during exercise in hot, dry conditionsSean R. Notley, Sheila Dervis, Martin P. Poirier, and Glen P. Kenny1 February 2019 | Journal of Applied Physiology, Vol. 126, No. 2Sex-dependent responses to exertional heat stroke in miceChristian K. Garcia, Alex J. Mattingly, Gerard P. Robinson, Orlando Laitano, Michelle A. King, Shauna M. Dineen, Lisa R. Leon, and Thomas L. Clanton19 September 2018 | Journal of Applied Physiology, Vol. 125, No. 3The effect of hot days on occupational heat stress in the manufacturing industry: implications for workers’ well-being and productivity30 March 2018 | International Journal of Biometeorology, Vol. 62, No. 7Luteal phase of the menstrual cycle increases sweating rate during exercise21 August 2006 | Brazilian Journal of Medical and Biological Research, Vol. 39, No. 9Effects of menstrual cycle and physical training on heat loss responses during dynamic exercise at moderate intensity in a temperate environmentTomoko Kuwahara, Yoshimitsu Inoue, Miyako Abe, Yuki Sato, and Narihiko Kondo1 May 2005 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 288, No. 5Sweat lactate response during cycling at 30°C and 18°C WBGTJournal of Sports Sciences, Vol. 22, No. 4Récupération post-exercice chez le sportif fumeurAnnales de Cardiologie et d'Angéiologie, Vol. 51, No. 6PRINCIPLES AND PRACTICES OF HEAT ADAPTATIONJournal of the Human-Environment System, Vol. 4, No. 1Can gender differences during exercise-heat stress be assessed by the physiological strain index?Daniel S. Moran, Yair Shapiro, Arie Laor, Sharona Izraeli, and Kent B. Pandolf1 June 1999 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 276, No. 6Thermoregulation in women during uncompensable heat stressJournal of Thermal Biology, Vol. 19, No. 5The relative influence of physical fitness, acclimatization state, anthropometric measures and gender on individual reactions to heat stressEuropean Journal of Applied Physiology and Occupational Physiology, Vol. 61, No. 5-6 More from this issue > Volume 49Issue 2August 1980Pages 254-261 Copyright & PermissionsCopyright © 1980 the American Physiological Societyhttps://doi.org/10.1152/jappl.1980.49.2.254PubMed7400008History Published online 1 August 1980 Published in print 1 August 1980 Metrics

Physiological responses of men and women to humid and dry heat.

ARTICLESPhysiological responses of men and women to humid and dry heatY. Shapiro, K. B. Pandolf, B. A. Avellini, N. A. Pimental, and R. F. GoldmanY. Shapiro, K. B. Pandolf, B. A. Avellini, N. A. Pimental, and R. F. GoldmanPublished Online:01 Jul 1980https://doi.org/10.1152/jappl.1980.49.1.1MoreSectionsPDF (2 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByExercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategiesJulien D. Périard, Thijs M. H. Eijsvogels, and Hein A. M. Daanen27 August 2021 | Physiological Reviews, Vol. 101, No. 4Sex Differences in Human Thermoregulation: Relevance for 2020 and BeyondR. Yanovich,* I. Ketko,* and N. Charkoudian15 April 2020 | Physiology, Vol. 35, No. 3Sex-dependent responses to exertional heat stroke in miceChristian K. Garcia, Alex J. Mattingly, Gerard P. Robinson, Orlando Laitano, Michelle A. King, Shauna M. Dineen, Lisa R. Leon, and Thomas L. Clanton19 September 2018 | Journal of Applied Physiology, Vol. 125, No. 3Personal cooling strategies to improve thermal comfort in warm indoor environments: Comparison of a conventional desk fan and air ventilation clothingEnergy and Buildings, Vol. 174Physiological Responses to Overdressing and Exercise-Heat Stress in Trained RunnersMedicine & Science in Sports & Exercise, Vol. 50, No. 6Current knowledge on the effects of humidity on physiological and psychological responsesJournal of the Human-Environment System, Vol. 20, No. 1Extremes of human heat tolerance: life at the precipice of thermoregulatory failureJournal of Thermal Biology, Vol. 29, No. 7-8Human ACE I/D polymorphism is associated with individual differences in exercise heat toleranceYuval Heled, Daniel S. Moran, Liran Mendel, Arie Laor, Elon Pras, and Yair Shapiro1 July 2004 | Journal of Applied Physiology, Vol. 97, No. 1Can gender differences during exercise-heat stress be assessed by the physiological strain index?Daniel S. Moran, Yair Shapiro, Arie Laor, Sharona Izraeli, and Kent B. Pandolf1 June 1999 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 276, No. 6The effects of heat and exercise on sweat iron lossMedicine &amp Science in Sports &amp Exercise, Vol. 28, No. 2Prediction modeling of physiological responses and human performance in the heatComputers in Biology and Medicine, Vol. 16, No. 5Heat balance and transfer in men and women exercising in hot-dry and hot-wet conditions*24 October 2007 | Ergonomics, Vol. 24, No. 5Sex differences in acclimation to a hot-dry environment†;27 March 2007 | Ergonomics, Vol. 23, No. 7 More from this issue > Volume 49Issue 1July 1980Pages 1-8 Copyright & PermissionsCopyright © 1980 the American Physiological Societyhttps://doi.org/10.1152/jappl.1980.49.1.1PubMed7399982History Published online 1 July 1980 Published in print 1 July 1980 Metrics

Heat tolerance following diuretic induced dehydration

In an effort to assess the effects of acute fluid loss on body temperature regulation during exercise, seven subjects (one female and six males) were studied on two occasions during two hours of cycling (35% Vo2max) in a hot environment (39 degrees C = DB, 35% = RH). One trial (D) was conducted following a 3% body weight reduction, achieved with 40-80 mg oral administration of a diuretic "lasix." A control exercise bout was performed with the subject normally hydrated (H). As a result of the diuresis, plasma volume (PV) decreased 15.3% (SE +/- 1.3), while heart rates during exercise increased 20-25 beats/min when compared to the H condition. Although significantly greater increases (P less than 0.05) in rectal and muscle temperatures occurred during exercise in the D trial, mean skin temperature (TS) was lower. Skin blood flow estimated from conductance values averaged 800 ml/min less during the D condition than during exercise in the H trial. Since the preliminary diuresis had no affect on sweat rate during exercise (D = 0.80 vs. H = 0.80 liters/hr), body heat dissipation appeared limited mainly by a reduction in peripheral blood flow. The diuretic induced dehydration was found to increase the sensitivity of some subjects to the exercise-heat stress, producing symptoms of heat exhaustion.

Heat tolerance of exercising lean and heavy prepubertal girls.

ARTICLESHeat tolerance of exercising lean and heavy prepubertal girlsE. M. Haymes, E. R. Buskirk, J. L. Hodgson, H. M. Lundegren, and W. C. NicholasE. M. Haymes, E. R. Buskirk, J. L. Hodgson, H. M. Lundegren, and W. C. NicholasPublished Online:01 May 1974https://doi.org/10.1152/jappl.1974.36.5.566MoreSectionsPDF (1 MB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByBody mass index, but not sex, influences exertional heat stroke risk in young healthy men and womenGabrielle E. W. Giersch, Kathryn M. Taylor, Aaron R. Caldwell, and Nisha Charkoudian13 December 2022 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 324, No. 1Human temperature regulation under heat stress in health, disease, and injuryMatthew N. Cramer, Daniel Gagnon, Orlando Laitano, and Craig G. Crandall19 August 2022 | Physiological Reviews, Vol. 102, No. 4Influence of sex and biological maturation on the sudomotor response to exercise-heat stress: are girls disadvantaged?Thomas H. Topham, James W. Smallcombe, Brad Clark, Harry A. Brown, Richard D. Telford, Ollie Jay, and Julien D. Périard11 July 2022 | American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, Vol. 323, No. 2Explained variance in the thermoregulatory responses to exercise: the independent roles of biophysical and fitness/fatness-related factorsMatthew N. Cramer and Ollie Jay1 November 2015 | Journal of Applied Physiology, Vol. 119, No. 9Dehydration and Thermal Strain in Junior Tennis22 April 2009 | American Journal of Lifestyle Medicine, Vol. 3, No. 4Thermoregulation during exercise in the heat in children: old concepts revisitedThomas Rowland1 August 2008 | Journal of Applied Physiology, Vol. 105, No. 2Energy Expenditure and [Vdot]O 2 Max of Female Athletes during Treadmill Exercise17 March 2013 | Research Quarterly. American Alliance for Health, Physical Education and Recreation, Vol. 47, No. 4 More from this issue > Volume 36Issue 5May 1974Pages 566-571 Copyright & PermissionsCopyright © 1974 the American Physiological Societyhttps://doi.org/10.1152/jappl.1974.36.5.566PubMed4826320History Published online 1 May 1974 Published in print 1 May 1974 Metrics

Heat tolerance and acclimatization to work in the heat in relation to age.

Heat tolerance and acclimatization to work in the heat in relation to age.

Heat of evaporation of sweat: thermodynamic considerations.

Heat of evaporation of sweat: thermodynamic considerations.

Resting energy metabolism and cardiorespiratory activity in the burro Equus asinus.

ArticleResting energy metabolism and cardiorespiratory activity in the burro Equus asinus.M K Yousef, and D B DillM K Yousef, and D B DillPublished Online:01 Aug 1969https://doi.org/10.1152/jappl.1969.27.2.229MoreSectionsPDF (919 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByCharacterization of sinoatrial automaticity in Microcebus murinus to study the effect of aging on cardiac activity and the correlation with longevity21 February 2023 | Scientific Reports, Vol. 13, No. 1Donkey Heart Rate and Heart Rate Variability: A Scoping Review25 January 2023 | Animals, Vol. 13, No. 3Genome-wide analysis identified candidate variants and genes associated with heat stress adaptation in Egyptian sheep breeds3 October 2022 | Frontiers in Genetics, Vol. 13Tolerance capability of desert sheep and goats to exercise heat stress under hot dry conditions, and its correlation with their production performanceSmall Ruminant Research, Vol. 205Physiological and genetic adaptation of desert sheep and goats to heat stress in the arid areas of EgyptSmall Ruminant Research, Vol. 203Cardiorespiratory coupling in cetaceans; a physiological strategy to improve gas exchange?1 January 2020 | Journal of Experimental Biology, Vol. 200Comparative analyses of basal rate of metabolism in mammals: data selection does matter27 July 2017 | Biological Reviews, Vol. 93, No. 1Improving working donkey (Equus asinus) welfare and management in Mali, West AfricaJournal of Veterinary Behavior, Vol. 7, No. 3Energy expenditure during level locomotion in large desert ungulates: the one‐humped camel and the domestic donkey18 February 2009 | Journal of Zoology, Vol. 277, No. 3Scaling the amplitudes of the circadian pattern of resting oxygen consumption, body temperature and heart rate in mammalsComparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Vol. 139, No. 1Day/night pattern of arterial blood gases in the cowRespiratory Physiology & Neurobiology, Vol. 140, No. 1Physiologic responses during an exhaustive driving test in donkeys: effect of conditioningApplied Animal Behaviour Science, Vol. 59, No. 1-3Energy Costs of Walking in Camels, Camelus dromedariusPhysiological Zoology, Vol. 62, No. 5Intake, digestibility and energy utilization of corrugated paper dietsAnimal Feed Science and Technology, Vol. 17, No. 1The Influence of Feeding and Fasting on the Metabolic Rate and Ventilation of the Amazonian Manatee (Trichechus inunguis)Physiological Zoology, Vol. 59, No. 5Basal metabolic rates in mammals: Taxonomic differences in the allometry of BMR and body massComparative Biochemistry and Physiology Part A: Physiology, Vol. 81, No. 4Properties of sweat, burro (Equus asinus) and manComparative Biochemistry and Physiology Part A: Physiology, Vol. 62, No. 2Respiratory activity and metabolic rate of burros, Equus asinus: Effect of ageComparative Biochemistry and Physiology Part A: Physiology, Vol. 60, No. 2Thyroid hormones and metabolic rate in burros, Equus asinus, and llamas, Lama glama: Effects of environmental temperatureComparative Biochemistry and Physiology Part A: Physiology, Vol. 60, No. 2The electrocardiogram of burrosJournal of Electrocardiology, Vol. 8, No. 3Temperature regulation in the somali donkey (Equus asinus)Comparative Biochemistry and Physiology Part A: Physiology, Vol. 39, No. 3Biochemical properties of the blood of three equinesComparative Biochemistry and Physiology Part B: Comparative Biochemistry, Vol. 39, No. 2 More from this issue > Volume 27Issue 2August 1969Pages 229-32 https://doi.org/10.1152/jappl.1969.27.2.229PubMed5796312History Published online 1 August 1969 Published in print 1 August 1969 Metrics

Comparison of thermoregulatory function in men and women.

Comparison of thermoregulatory function in men and women.

Relationship of evaporative rates to serum [Na+], [K+], and osmolarity in acute heat stress.

ArticleRelationship of evaporative rates to serum [Na+], [K+], and osmolarity in acute heat stress.L C Senay JrL C Senay JrPublished Online:01 Aug 1968https://doi.org/10.1152/jappl.1968.25.2.149MoreSectionsPDF (811 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation Cited ByThermal Physiology in the USA: A 100-Year History of the Science and Its Scientists (1880–1980)23 September 2022Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategiesJulien D. Périard, Thijs M. H. Eijsvogels, and Hein A. M. Daanen27 August 2021 | Physiological Reviews, Vol. 101, No. 4Effects of natural polyphenol-rich pomegranate juice supplementation on plasma ion and lipid profiles following resistance exercise: a placebo-controlled trial16 April 2020 | Nutrition & Metabolism, Vol. 17, No. 1Physiological factors characterizing heat-vulnerable older adults: A narrative reviewEnvironment International, Vol. 144The effects of exercise and passive heating on the sweat glands ion reabsorption rates27 February 2018 | Physiological Reports, Vol. 6, No. 5Interactions between body fluid homeostasis and thermoregulation in humansPhysiological adjustments to hypohydration: Impact on thermoregulationAutonomic Neuroscience, Vol. 196Heat Stroke16 March 2015The effect of prescribed fluid consumption on physiology and work behavior of wildfire fightersApplied Ergonomics, Vol. 44, No. 3Human Water and Electrolyte Balance18 June 2012Pre-shift fluid intake: Effect on physiology, work and drinking during emergency wildfire fightingApplied Ergonomics, Vol. 43, No. 3Integrated Physiological Mechanisms of Exercise Performance, Adaptation, and Maladaptation to Heat Stress1 October 2011Sports Drinks, Exercise Training, and CompetitionCurrent Sports Medicine Reports, Vol. 7, No. 4Hydration at the Work SiteJournal of the American College of Nutrition, Vol. 26, No. sup5Endurance Running Performance after 48 h of Restricted Fluid and/or Energy IntakeMedicine & Science in Sports & Exercise, Vol. 39, No. 2Role of Sodium in Fluid Homeostasis with ExerciseJournal of the American College of Nutrition, Vol. 25, No. sup3The effects of different air velocities on heat storage and body temperature in humans cycling in a hot, humid environmentActa Physiologica Scandinavica, Vol. 183, No. 3The Temperature Regulatory SystemSpecial issues and concerns for the high school- and college-aged athletesPediatric Clinics of North America, Vol. 49, No. 3Rehydration after Exercise with Fresh Young Coconut Water, Carbohydrate-Electrolyte Beverage and Plain Water.Journal of PHYSIOLOGICAL ANTHROPOLOGY and Applied Human Science, Vol. 21, No. 2Hydration effects on thermoregulation and performance in the heatComparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, Vol. 128, No. 4Fluid and electrolyte supplementation for exercise heat stress,,,The American Journal of Clinical Nutrition, Vol. 72, No. 2Blood volume: importance and adaptations to exercise training, environmental stresses, and trauma/sicknessMedicine & Science in Sports & Exercise, Vol. 32, No. 2Posicionamento Oficial: exercício e reposição líquidaRevista Brasileira de Medicina do Esporte, Vol. 5, No. 1Major mineral concentrations in human milk do not change after maximal exercise testingThe American Journal of Clinical Nutrition, Vol. 68, No. 2Dehydration markedly impairs cardiovascular function in hyperthermic endurance athletes during exerciseGonzález-Alonso, José, Ricardo Mora-Rodríguez, Paul R. Below, and Edward F. Coyle1 April 1997 | Journal of Applied Physiology, Vol. 82, No. 4Integrative regulations of body temperature and body fluid in humans exercising in a hot environmentInternational Journal of Biometeorology, Vol. 40, No. 1Body Fluid Balance During Heat Stress in Humans1 January 2011ACSM Position Stand: Exercise and Fluid ReplacementMedicine &amp Science in Sports &amp Exercise, Vol. 28, No. 10Changes in plasma volume during hypohydration and rehydration in subjects from the tropicsEuropean Journal of Applied Physiology and Occupational Physiology, Vol. 61, No. 3-4Factors affecting the regulation of body temperature during exerciseJournal of Thermal Biology, Vol. 8, No. 1-2A Brief Summary…HEAT ACCLIMATISATION AND THE SWEATING RESPONSECalorimetric analysis of the effect of drinking saline solution on whole-body sweatingPfl�gers Archiv European Journal of Physiology, Vol. 331, No. 2Calorimetric analysis of the effect of drinking saline solution on whole-body sweatingPfl�gers Archiv European Journal of Physiology, Vol. 331, No. 2 More from this issue > Volume 25Issue 2August 1968Pages 149-52 https://doi.org/10.1152/jappl.1968.25.2.149PubMed5666089History Published online 1 August 1968 Published in print 1 August 1968 Metrics

"Helping Your Doctor"

<h3>Objective</h3> Pregnant women are advised to avoid heat stress (eg, excessive exercise and/or heat exposure) due to the risk of teratogenicity associated with maternal hyperthermia; defined as a core temperature (T_core) ≥39.0°C. However, guidelines are ambiguous in terms of critical combinations of climate and activity to avoid and may therefore unnecessarily discourage physical activity during pregnancy. Thus, the primary aim was to assess T_core elevations with different characteristics defining exercise and passive heat stress (intensity, mode, ambient conditions, duration) during pregnancy relative to the critical maternal T_core of ≥39.0°C. <h3>Design</h3> Systematic review with best evidence synthesis. <h3>Data sources</h3> EMBASE, MEDLINE, SCOPUS, CINAHL and Web of Science were searched from inception to 12 July 2017. <h3>Study eligibility criteria</h3> Studies reporting the T_core response of pregnant women, at any period of gestation, to exercise or passive heat stress, were included. <h3>Results</h3> 12 studies satisfied our inclusion criteria (n=347). No woman exceeded a T_core of 39.0°C. The highest T_core was 38.9°C, reported during land-based exercise. The highest mean end-trial T_core was 38.3°C (95% CI 37.7°C to 38.9°C) for land-based exercise, 37.5°C (95% CI 37.3°C to 37.7°C) for water immersion exercise, 36.9°C (95% CI 36.8°C to 37.0°C) for hot water bathing and 37.6°C (95% CI 37.5°C to 37.7°C) for sauna exposure. <h3>Conclusion</h3> The highest individual core temperature reported was 38.9°C. Immediately after exercise (either land based or water immersion), the highest mean core temperature was 38.3°C; 0.7°C below the proposed teratogenic threshold. Pregnant women can safely engage in: (1) exercise for up to 35 min at 80%–90% of their maximum heart rate in 25°C and 45% relative humidity (RH); (2) water immersion (≤33.4°C) exercise for up to 45 min; and (3) sitting in hot baths (40°C) or hot/dry saunas (70°C; 15% RH) for up to 20 min, irrespective of pregnancy stage, without reaching a core temperature exceeding the teratogenic threshold.

Maximal oxygen intake as an objective measure of cardio-respiratory performance.

Maximal oxygen intake as an objective measure of cardio-respiratory performance.