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Notley SR, Mitchell D, Taylor NAS. A century of exercise physiology: concepts that ignited the study of human thermoregulation. Part 3: Heat and cold tolerance during exercise. Eur J Appl Physiol 2024; 124:1-145. [PMID: 37796292 DOI: 10.1007/s00421-023-05276-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 07/04/2023] [Indexed: 10/06/2023]
Abstract
In this third installment of our four-part historical series, we evaluate contributions that shaped our understanding of heat and cold stress during occupational and athletic pursuits. Our first topic concerns how we tolerate, and sometimes fail to tolerate, exercise-heat stress. By 1900, physical activity with clothing- and climate-induced evaporative impediments led to an extraordinarily high incidence of heat stroke within the military. Fortunately, deep-body temperatures > 40 °C were not always fatal. Thirty years later, water immersion and patient treatments mimicking sweat evaporation were found to be effective, with the adage of cool first, transport later being adopted. We gradually acquired an understanding of thermoeffector function during heat storage, and learned about challenges to other regulatory mechanisms. In our second topic, we explore cold tolerance and intolerance. By the 1930s, hypothermia was known to reduce cutaneous circulation, particularly at the extremities, conserving body heat. Cold-induced vasodilatation hindered heat conservation, but it was protective. Increased metabolic heat production followed, driven by shivering and non-shivering thermogenesis, even during exercise and work. Physical endurance and shivering could both be compromised by hypoglycaemia. Later, treatments for hypothermia and cold injuries were refined, and the thermal after-drop was explained. In our final topic, we critique the numerous indices developed in attempts to numerically rate hot and cold stresses. The criteria for an effective thermal stress index were established by the 1930s. However, few indices satisfied those requirements, either then or now, and the surviving indices, including the unvalidated Wet-Bulb Globe-Thermometer index, do not fully predict thermal strain.
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Affiliation(s)
- Sean R Notley
- Defence Science and Technology Group, Department of Defence, Melbourne, Australia
- School of Human Kinetics, University of Ottawa, Ottawa, Canada
| | - Duncan Mitchell
- Brain Function Research Group, School of Physiology, University of the Witwatersrand, Johannesburg, South Africa
- School of Human Sciences, University of Western Australia, Crawley, Australia
| | - Nigel A S Taylor
- Research Institute of Human Ecology, College of Human Ecology, Seoul National University, Seoul, Republic of Korea.
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Maley MJ, Minett GM, Bach AJE, Zietek SA, Stewart KL, Stewart IB. Internal and external cooling methods and their effect on body temperature, thermal perception and dexterity. PLoS One 2018; 13:e0191416. [PMID: 29357373 PMCID: PMC5777660 DOI: 10.1371/journal.pone.0191416] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/04/2018] [Indexed: 12/19/2022] Open
Abstract
Objective The present study aimed to compare a range of cooling methods possibly utilised by occupational workers, focusing on their effect on body temperature, perception and manual dexterity. Methods Ten male participants completed eight trials involving 30 min of seated rest followed by 30 min of cooling or control of no cooling (CON) (34°C, 58% relative humidity). The cooling methods utilised were: ice cooling vest (CV0), phase change cooling vest melting at 14°C (CV14), evaporative cooling vest (CVEV), arm immersion in 10°C water (AI), portable water-perfused suit (WPS), heliox inhalation (HE) and ice slushy ingestion (SL). Immediately before and after cooling, participants were assessed for fine (Purdue pegboard task) and gross (grip and pinch strength) manual dexterity. Rectal and skin temperature, as well as thermal sensation and comfort, were monitored throughout. Results Compared with CON, SL was the only method to reduce rectal temperature (P = 0.012). All externally applied cooling methods reduced skin temperature (P<0.05), though CV0 resulted in the lowest skin temperature versus other cooling methods. Participants felt cooler with CV0, CV14, WPS, AI and SL (P<0.05). AI significantly impaired Purdue pegboard performance (P = 0.001), but did not affect grip or pinch strength (P>0.05). Conclusion The present study observed that ice ingestion or ice applied to the skin produced the greatest effect on rectal and skin temperature, respectively. AI should not be utilised if workers require subsequent fine manual dexterity. These results will help inform future studies investigating appropriate pre-cooling methods for the occupational worker.
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Affiliation(s)
- Matthew J. Maley
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
- * E-mail:
| | - Geoffrey M. Minett
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
| | - Aaron J. E. Bach
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
| | - Stephanie A. Zietek
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
| | - Kelly L. Stewart
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
| | - Ian B. Stewart
- Institute of Health and Biomedical Innovation, School of Exercise and Nutrition Sciences, Queensland University of Technology, Brisbane, Australia
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Inert gas narcosis has no influence on thermo-tactile sensation. Eur J Appl Physiol 2011; 112:1929-35. [PMID: 21932070 DOI: 10.1007/s00421-011-2169-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2011] [Accepted: 09/04/2011] [Indexed: 10/17/2022]
Abstract
Contribution of skin thermal sensors under inert gas narcosis to the raising hypothermia is not known. Such information is vital for understanding the impact of narcosis on behavioural thermoregulation, diver safety and judgment of thermal (dis)comfort in the hyperbaric environment. So this study aimed at establishing the effects of normoxic concentration of 30% nitrous oxide (N(2)O) on thermo-tactile threshold sensation by studying 16 subjects [eight females and eight males; eight sensitive (S) and eight non-sensitive (NS) to N(2)O]. Their mean (SD) age was 22.1 (1.8) years, weight 72.8 (15.3) kg, height 1.75 (0.10) m and body mass index 23.8 (3.8) kg m(-2). Quantitative thermo-tactile sensory testing was performed on forearm, upper arm and thigh under two experimental conditions: breathing air (air trial) and breathing normoxic mixture of 30% N(2)O (N(2)O trial) in the mixed sequence. Difference in thermo-tactile sensitivity thresholds between two groups of subjects in two experimental conditions was analysed by 3-way mixed-model analysis of covariance. There were no statistically significant differences in thermo-tactile thresholds either between the Air and N(2)O trials, or between S and NS groups, or between females and males, or with respect to body mass index. Some clinically insignificant lowering of thermo-tactile thresholds occurred only for warm thermo-tactile thresholds on upper arm and thigh. The results indicated that normoxic mixture of 30% N(2)O had no influence on thermo-tactile sensation in normothermia.
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Kayar SR, Parker EC, Harabin AL. Metabolism and thermoregulation in guinea pigs in hyperbaric hydrogen: Effects of pressure. J Therm Biol 1997. [DOI: 10.1016/s0306-4565(96)00032-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Brocas J, Fromageot C. Thermoregulation in homeotherms: central temperature results from optimization of energy transfers. BIOLOGICAL CYBERNETICS 1996; 74:225-234. [PMID: 8867468 DOI: 10.1007/bf00652223] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In contrast to the classical homeostatic concept of the constancy of the central temperature, this study proposes an original model of thermoregulation based on the optimization of energy transfers. Exchange of the energy consumed or produced by the cell between the cell and the external medium has an associated energy cost. The different variables of the internal medium-flows, pressures, concentrations and also temperatures, since heat is but a particular form of energy--are continuously set at optimal values such that this cost is always minimal for the prevailing constraints with which the organism is faced. The proposed thermoregulatory model accounts for the physiological spatial and temporal variability of the body's temperatures. The predictive curves suggest a new approach to experimental studies concerned with thermal regulation and throw new light on their results.
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Affiliation(s)
- J Brocas
- Department of Physiology, René Descartes University, Paris, France
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Muller FL. A field study of the ventilatory response to ambient temperature and pressure in sport diving. Br J Sports Med 1995; 29:185-90. [PMID: 8800853 PMCID: PMC1332311 DOI: 10.1136/bjsm.29.3.185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
This study reports on the relationship between minute ventilation (VE) and environmental variables of temperature (T) and pressure (P) during open water diving. The author conducted a total of 38 dives involving either a light (20 dives) or a moderate (18 dives) level of physical activity. Within each of these groups, P and T taken together accounted for about two thirds of the variance in the VE data. A very significant increase in VE was observed as T decreased (1 < T(degrees C) < 22), and the magnitude of this increase at a given pressure level was similar in the 'light' and the 'moderate' data sets. A second order observation, particularly notable at lower temperature, was the decrease in VE with increasing pressure under conditions of light work. Empirical functions of the from VE = A+B/P n[1 + exp(T - 8)/10], where A, B, and n are adjustable variables, could accommodate both data sets over the whole range of T and P. These results are the first obtained under actual diving conditions to provide evidence for interactions between P, T, and VE. Understanding the physiological mechanisms by which these interactions occur would assist in appreciation of the limitations imposed on scuba divers by the environmental conditions as they affect their ventilatory responses.
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Affiliation(s)
- F L Muller
- Department of Oceanography, The University, Southampton, UK
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Rønnestad I, Thorsen E, Segadal K, Hope A. Bronchial response to breathing dry gas at 3.7 MPa ambient pressure. EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY AND OCCUPATIONAL PHYSIOLOGY 1994; 69:32-5. [PMID: 7957153 DOI: 10.1007/bf00867924] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
In diving, pulmonary mechanical function is limited by the increased density of the gas breathed. Breathing cold and dry gas may cause an additional increase in airways resistance. We have measured forced vital capacity, forced expired volume in 1 s (FEV1) and forced midexpiratory flow rate (FEF25%-75%) before and after breathing dry or humid gas at 29-32 degrees C during a standardized exercise intensity on a cycle ergometer at an ambient pressure of 3.7 MPa. The atmosphere was a helium and oxygen mixture with a density of 6.8 kg.m-3. Six professional saturation divers aged 26-37 years participated in the study. There were no significant differences in convective respiratory heat loss between the exposures. The mean evaporative heat loss was 67 W (range 59-89) breathing dry gas and 37 W (range 32-43) breathing humid gas, corresponding to water losses of 1.7 g.min-1 (range 1.5-2.2) and 0.9 g.min-1 (range 0.8-1.1), respectively. There was a significant reduction in FEV1 of 4.6 (SD 3.6)% (P < 0.05), and in FEF25%-75% of 5.8 (SD 4.7)% (P < 0.05) after breathing dry gas. There were no changes after breathing humid gas. By warming and humidifying the gas breathed in deep saturation diving bronchoconstriction may be prevented.
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Affiliation(s)
- I Rønnestad
- Norwegian Underwater Technology Centre A/S, Ytre Laksevåg
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Burnet H, Reynaud-Gaubert M, Lucciano M, Jammes Y. Relationship between inspired and expired gas temperatures in a hyperbaric environment. RESPIRATION PHYSIOLOGY 1992; 90:377-86. [PMID: 1480846 DOI: 10.1016/0034-5687(92)90116-e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
When breathing room air at sea level the expired gas temperature (TE) increases in proportion to the inspired one (TI). Previous studies conducted under hyperbaric conditions have assumed that the TE vs TI relationship was the same when humans breathed room air at atmospheric pressure or helium-oxygen mixture under hyperbaric conditions. We hypothesized that the use of dilutant gases, as helium (He) or hydrogen (H2), having low density but high specific heat compared to nitrogen, could change the TE vs TI regression. The present study was conducted on 3 professional divers participating in the COMEX Hydra IX experiment. Three conditions were studied: A, (23.5 ATA, He-H2-O2 mixture); B, (21 ATA, H2-O2 mixture); and C, (21 ATA, He-O2 mixture). In each condition six different inspired temperatures were tested, while minute ventilation, TI and TE values were measured simultaneously. In all cases a linear relationship was found between TE and TI, but the slopes of the regression lines obtained in conditions A and B (gas mixture containing H2) were significantly lower than in condition C (He-O2 mixture). Computation of the convective respiratory heat loss (Cr) revealed that, when the subjects breathed the coldest gas mixtures (+10 degrees C), Cr value was 1.6 times higher in condition B than in C. These data are consistent with theoretical considerations and they demonstrate that a single equation cannot be used to predict the TE vs TI relationship in all environmental circumstances.
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Affiliation(s)
- H Burnet
- Laboratoire de Biologie des Hautes pressions, URA 1330-CNRS, Faculté de Médecine-Nord, Marseille, France
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Martini S, Brubakk AO, Bech C. Effect of high pressure on metabolic response to cold in rats. ACTA PHYSIOLOGICA SCANDINAVICA 1989; 135:359-66. [PMID: 2929374 DOI: 10.1111/j.1748-1716.1989.tb08588.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The ability of rats to regulate body temperature in a cool helium-oxygen (heliox) atmosphere at high pressure was studied. Thermoregulatory ability in seven awake rats was assessed in a pressure chamber at 1.5, 21 and 41 ATA by monitoring body temperature and oxygen consumption during a gradual reduction of ambient temperature. Body temperature was measured by a radiotelemetry transmitter implanted into the intraperitoneal cavity. The thermal conductance of the rats increased from 0.37 to 0.75 W kg-1 degrees C-1 as air was substituted by heliox and increased further to 1.47 and 1.81 W kg-1 degrees C-1 as the pressure was increased to 21 and 41 ATA, respectively. At high pressure the rats were able to maintain body temperature until the metabolic rate reached a value of 21.9 +/- 2.0 W kg-1, which corresponds to peak metabolic rate. This occurred at an ambient temperature of approximately 21 degrees C. Below this ambient temperature the rats did not manage to maintain body temperature. The results show that the thermal effector mechanisms of rats respond adequately to a slowly decreasing ambient temperature in hyperbaric heliox environments.
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Affiliation(s)
- S Martini
- Department of Biomedical Engineering, University of Trondheim, Norway
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Flook V. Physics and physiology in the hyperbaric environment. CLINICAL PHYSICS AND PHYSIOLOGICAL MEASUREMENT : AN OFFICIAL JOURNAL OF THE HOSPITAL PHYSICISTS' ASSOCIATION, DEUTSCHE GESELLSCHAFT FUR MEDIZINISCHE PHYSIK AND THE EUROPEAN FEDERATION OF ORGANISATIONS FOR MEDICAL PHYSICS 1987; 8:197-230. [PMID: 3304804 DOI: 10.1088/0143-0815/8/3/001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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11
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Mekjavic IB, Morrison JB. A model of shivering thermogenesis based on the neurophysiology of thermoreception. IEEE Trans Biomed Eng 1985; 32:407-17. [PMID: 4007904 DOI: 10.1109/tbme.1985.325467] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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King FG, Manson HJ, Snellen JW, Chang KS. Demonstration of a problem in estimating sensible heat loss from the respiratory tract by thermometry. CANADIAN ANAESTHETISTS' SOCIETY JOURNAL 1984; 31:460-5. [PMID: 6744095 DOI: 10.1007/bf03015426] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
We have investigated sensible respiratory loss, which is usually taken as the product of expired volume and the temperature difference between inspired and expired air (VE X delta T). Air temperature was measured with a 0.122 mm copper-constantan thermocouple mounted in the mouthpiece of a T-piece breathing system, and expired volume with a pneumotachograph. Changing air temperature (delta T) at the mouth and expired air volume (VE) were recorded simultaneously while the subject voluntarily breathed at different tidal volumes and rates. Inspired temperatures were controlled at 12.05 degrees C, 21.80 degrees C and 25.74 degrees C at a low dewpoint temperature of 4-5 degrees C. Temperature volume "loops" were constructed using an x-y plotter. The areas of each "loop" and enclosing rectangle (VE X delta T) were measured. The difference was divided by the weight of the rectangle to give the percentage of overestimation of sensible heat loss, which ranged from 5.5 to 17.2 per cent. The error increased significantly with decreasing tidal volume and increasing respiratory rate.
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