Highlights
- •In humans, heat stress arises from metabolic and/or environmental heat sources.
- •Thermoregulatory responses facilitate heat loss to prevent excessive heat storage.
- •The physical properties of the skin and environment dictate the rate of heat loss.
- •Core temperature changes reflect heat storage and body morphology.
Abstract
Humans maintain a relatively constant core temperature through the dynamic balance
between endogenous heat production and heat dissipation to the surrounding environment.
In response to metabolic or environmental disturbances to heat balance, the autonomic
nervous system initiates cutaneous vasodilation and eccrine sweating to facilitate
higher rates of dry (primarily convection and radiation) and evaporative transfer
from the body surface; however, absolute heat losses are ultimately governed by the
properties of the skin and the environment. Over the duration of a heat exposure,
the cumulative imbalance between heat production and heat dissipation leads to body
heat storage, but the consequent change in core temperature, which has implications
for health and safety in occupational and athletic settings particularly among certain
clinical populations, involves a complex interaction between changes in body heat
content and the body's morphological characteristics (mass, surface area, and tissue
composition) that collectively determine the body's thermal inertia. The aim of this
review is to highlight the biophysical aspects of human core temperature regulation
by outlining the principles of human energy exchange and examining the influence of
body morphology during exercise and environmental heat stress. An understanding of
the biophysical factors influencing core temperature will enable researchers and practitioners
to better identify and treat individuals/populations most vulnerable to heat illness
and injury during exercise and extreme heat events. Further, appropriate guidelines
may be developed to optimize health, safety, and work performance during heat stress.
Keywords
To read this article in full you will need to make a payment
Purchase one-time access:
Academic & Personal: 24 hour online accessCorporate R&D Professionals: 24 hour online accessOne-time access price info
- For academic or personal research use, select 'Academic and Personal'
- For corporate R&D use, select 'Corporate R&D Professionals'
Subscribe:
Subscribe to Autonomic Neuroscience: Basic and ClinicalAlready a print subscriber? Claim online access
Already an online subscriber? Sign in
Register: Create an account
Institutional Access: Sign in to ScienceDirect
References
- Effects of obesity on body temperature in otherwise-healthy females when controlling hydration and heat production during exercise in the heat.Eur. J. Appl. Physiol. 2015; 115: 167-176https://doi.org/10.1007/s00421-014-3002-y
- Effects of varied air velocity on sweating and evaporative rates during exercise.J. Appl. Physiol. 1992; 73: 2668-2674
- Efficiency of sweat evaporation in unacclimatized man working in a hot humid environment.Eur. J. Appl. Physiol. Occup. Physiol. 1985; 54: 480-487
- Thermal insulation for preventing inadvertent perioperative hypothermia.Cochrane Database Syst. Rev. 2014; 6CD009908https://doi.org/10.1002/14651858.CD009908.pub2
- Human morphology and temperature regulation.Int. J. Biometeorol. 1999; 43: 99-109
- The regulation of the body-temperature during work performed with the arms and with the legs.Acta Physiol. Scand. 1947; 14: 373-382https://doi.org/10.1111/j.1748-1716.1947.tb00473.x
- Work capacity in mean and women with specific reference to age.Acta Physiol. Scand. 1960; 49: 1-92
- Textbook of Work Physiology.third ed. McGraw-Hill, New York1986
- Hyperthermia and fever control in brain injury.Crit. Care Med. Ther. Temp. Manag. State Art Crit. Ill. 2009; 37https://doi.org/10.1097/CCM.0b013e3181aa5e8d
- The metabolic cost of fever.Can. J. Physiol. Pharmacol. 1987; 65: 1248-1254
- Running economy: measurement, norms, and determining factors.Sports Med.Open. 2015; 1https://doi.org/10.1186/s40798-015-0007-y
- Heat tolerance of exercising obese and lean women.J. Appl. Physiol. 1969; 26: 403-409
- Increasing passive energy expenditure during clerical work.Eur. J. Appl. Physiol. 2008; 103: 353-360https://doi.org/10.1007/s00421-008-0713-y
- Heart rate and body temperature as indices of metabolic rate during work.Arbeitsphysiologie. 1950; 14 (Int. Z. Für Angew. Physiol): 255-260
- Evaporation of sweat from sedentary man in humid environments.J. Appl. Physiol. 1977; 42: 767-772
- Energy expenditure in level and grade walking.J. Appl. Physiol. 1960; 15: 1015-1021
- Experimental study of convective heat transfer coefficient for the human body in water.J. Appl. Physiol. 1977; 42: 93-100
- Respiratory heat loss during work at various ambient temperatures.Respir. Physiol. 1990; 79: 145-150
- Human skin wettedness and evaporative efficiency of sweating.J. Appl. Physiol. 1979; 46: 522-528
- Influence of air velocity and heat acclimation on human skin wettedness and sweating efficiency.J. Appl. Physiol. 1979; 47: 1194-1200
- Exertional heat stroke in competitive athletes.Curr. Sports Med. Rep. 2005; 4: 309-317
- National Athletic Trainers' Association position statement: exertional heat illnesses.J. Athl. Train. 2015; 50: 986-1000https://doi.org/10.4085/1062-6050-50.9.07
- Cold water immersion: the gold standard for exertional heatstroke treatment.Exerc. Sport Sci. Rev. 2007; 35: 141-149https://doi.org/10.1097/jes.0b013e3180a02bec
- The effect of wind speed on maximum evaporative capacity in man.J. Physiol. 1959; 147: 253-259
- Environmental temperature and energy expenditures.J. Appl. Physiol. 1963; 18: 65-68
- Local sweating on the forehead, but not forearm, is influenced by aerobic fitness independently of heat balance requirements during exercise.Exp. Physiol. 2012; 97: 572-582https://doi.org/10.1113/expphysiol.2011.061374
- Explained variance in the thermoregulatory responses to exercise: The independent roles of biophysical and fitness/fatness-related factors.J. Appl. Physiol. 2015; (jap.00281.2015)https://doi.org/10.1152/japplphysiol.00281.2015
- Selecting the correct exercise intensity for unbiased comparisons of thermoregulatory responses between groups of different mass and surface area.J. Appl. Physiol. 2014; 116 (Bethesda Md 1985): 1123-1132https://doi.org/10.1152/japplphysiol.01312.2013
- Compensatory hyperhidrosis following thoracic sympathectomy: a biophysical rationale.Am. J. Physiol Regul. Integr. Comp. Physiol. 2012; 302: R352-R356https://doi.org/10.1152/ajpregu.00419.2011
- Human cardiovascular responses to passive heat stress.Compr. Physiol. 2015; 5: 17-43https://doi.org/10.1002/cphy.c140015
- A physiologist's view of running economy.Med. Sci. Sports Exerc. 1985; 17: 332-338
- Thermoregulation during exercise in relation to sex and age.Eur. J. Appl. Physiol. Occup. Physiol. 1979; 42: 71-79
- A comparison of thermoregulatory responses to exercise between mass-matched groups with large differences in body fat.J. Appl. Physiol. 2015; (jap.00906.2015)https://doi.org/10.1152/japplphysiol.00906.2015
- Sweat electrolytes in desert walks.J. Appl. Physiol. 1967; 23: 746-751
- Responses of lean and obese boys to repeated summer exercise in the heat bouts.Med. Sci. Sports Exerc. 2009; 41: 279-289https://doi.org/10.1249/MSS.0b013e318185d341
- A formula to estimate surface area if height and weight are known.Arch. Intern. Med. 1916; 17: 863-871
- Cutaneous blood flow during exercise is higher in endurance-trained humans.J. Appl. Physiol. 2000; 88 (Bethesda Md 1985): 738-744
- Mechanical efficiency in rowing.Eur. J. Appl. Physiol. 1986; 55: 471-475
- Muscular efficiency during steady-rate exercise: effects of speed and work rate.J. Appl. Physiol. 1975; 38: 1132-1139
- Mechanisms of heat exchange: biophysics and physiology.in: Fregly M.J. Blatteis C.M. Handbook of Physiology. Environmental Physiology. American Physiological Society, Bethesda, MD1996: 45-84
- An improved method for the continuous measurement of the rate of oxygen consumption for human subjects.Science. 1941; 93: 551-552https://doi.org/10.1126/science.93.2423.551
- A new physiological variable associated with sensible and insensible perspiration.Am. J. Phys. 1937; 120: 277-287
- Heat exchange between the human skin surface and thermal environment.in: Handbook of Physiology: Reactions to Environmental Agents. American Physiological Society, Bethesda, MD1977: 69-92
- The evaporative requirement for heat balance determines whole-body sweat rate during exercise under conditions permitting full evaporation.J. Physiol. 2013; 591: 2925-2935https://doi.org/10.1113/jphysiol.2012.248823
- Nongrafted skin area best predicts exercise core temperature responses in burned humans.Med. Sci. Sports Exerc. 2015; 47: 2224-2232https://doi.org/10.1249/MSS.0000000000000655
- Effects of prolonged exercise at a similar percentage of maximal oxygen consumption in trained and untrained subjects.Eur. J. Appl. Physiol. 1991; 63: 430-435
- Rewarming postoperative patients: lights, blankets, or forced warm air.J. Post Anesth. Nurs. 1991; 6: 387-393
- Development of a New Thermal Index. Estimation of the Effect of Climate on Man.UNESCO, Haifa1963
- Longitudinal assessment of energy expenditure in pregnancy by the doubly labeled water method.Am. J. Clin. Nutr. 1993; 57: 494-505
- Predictors of sweat loss in man during prolonged exercise.Eur. J. Appl. Physiol. Occup. Physiol. 1989; 58: 348-352
- Radiation area of the human body.J. Appl. Physiol. 1952; 5: 24-37
- Human surface to mass ratio and body core temperature in exercise heat stress-a concept revisited.J. Therm. Biol. 2001; 26: 387-393https://doi.org/10.1016/S0306-4565(01)00049-3
- Relevance of individual characteristics for human heat stress response is dependent on exercise intensity and climate type.Eur. J. Appl. Physiol. 1998; 77: 231-241https://doi.org/10.1007/s004210050327
- Male and female upper body sweat distribution during running measured with technical absorbents.Eur. J. Appl. Physiol. 2008; 104: 245-255
- Heat tolerance of exercising lean and heavy prepubertal girls.J. Appl. Physiol. 1974; 36: 566-571
- Heat tolerance of exercising lean and obese prepubertal boys.J. Appl. Physiol. 1975; 39: 457-461
- Age, fitness, and regional blood flow during exercise in the heat.J. Appl. Physiol. 1997; 82: 1126-1135
- Sex differences in the effects of physical training on sweat gland responses during a graded exercise.Exp. Physiol. 2010; 95: 1026-1032https://doi.org/10.1113/expphysiol.2010.053710
- Ergonomics of the Thermal Environment. Instruments for Measuring Physical Quantities (No. ISO 7726:1998).International Organization for Standardization, Geneva1998
- Large differences in peak oxygen uptake do not independently alter changes in core temperature and sweating during exercise.Am. J. Physiol. Regul. Integr. Comp. Physiol. 2011; 301: R832-R841https://doi.org/10.1152/ajpregu.00257.2011
- Should electric fans be used during a heat wave?.Appl. Ergon. 2015; 46: 137-143https://doi.org/10.1016/j.apergo.2014.07.013
- Cutaneous vasodilator and vasoconstrictor mechanisms in temperature regulation.Compr. Physiol. 2014; 4: 33-89https://doi.org/10.1002/cphy.c130015
- The physiology of the world record holder for the women's marathon.Int. J. Sports Sci. Coach. 2006; 1: 101-116
- Physiological correlates of heat intolerance.Sports Med. 1985; 2: 279-286
- Thermometry, calorimetry, and mean body temperature during heat stress.Compr. Physiol. 2013; 3: 1689-1719https://doi.org/10.1002/cphy.c130011
- The Stress of Hot Environments.Cambridge University Press, London1972
- Errors arising from the use of mean heat exchange coefficients in the calculation of the heat exchanges of a cylindrical body in a traverse wind.in: Temperature: Its Measurement and Control in Industry. Reinhold, New York1963: 183-189
- Responses of obese and lean girls exercising under heat and thermoneutral conditions.J. Pediatr. 2013; 162: 1054-1060https://doi.org/10.1016/j.jpeds.2012.10.047
- Thermophysical Properties of Water and Steam.in: Handbook of Chemistry and Physics. CRC Press, New York2015: 1-3
- The energy expenditure of using a “walk-and-work” desk for office workers with obesity.Br. J. Sports Med. 2007; 41: 558-561https://doi.org/10.1136/bjsm.2006.032755
- Energy expenditure of nonexercise activity.Am. J. Clin. Nutr. 2000; 72: 1451-1454
- Effect of individual variation on upper limit of prescriptive zone of climates.J. Appl. Physiol. 1970; 28: 57-62
- The key to top-level endurance running performance: a unique example.Br. J. Sports Med. 2008; 42 (discussion 174): 172-174https://doi.org/10.1136/bjsm.2007.040725
- Basal metabolic rate, fat-free mass, and body cell mass during energy restriction.Metabolism. 1992; 41: 450-456
- Sweat secretion from the torso during passively-induced and exercise-related hyperthermia.Eur. J. Appl. Physiol. 2008; 104: 265-270https://doi.org/10.1007/s00421-007-0646-x
- Local differences in sweat secretion from the head during rest and exercise in the heat.Eur. J. Appl. Physiol. 2008; 104: 257-264https://doi.org/10.1007/s00421-007-0645-y
- Advantages of smaller body mass during distance running in warm, humid environments.Pflugers Arch. 2000; 441: 359-367
- Heat flow and distribution during induction of general anesthesia.Anesthesiology. 1995; 82: 662-673
- A comprehensive data base for estimating clothing insulation.ASHRAE Trans. 1985; 91: 29-47
- Convective heat transfer from man and other animals.in: Monteith J.L. Mounts L.E. Heat Loss From Animals and Man. Butterworths, London1974
- Respiratory weight losses during exercise.J. Appl. Physiol. 1972; 32: 474-476
- Assessing neonatal heat balance and physiological strain in newborn infants nursed under radiant warmers in intensive care with fentanyl sedation.Eur. J. Appl. Physiol. 2014; 114: 2539-2549https://doi.org/10.1007/s00421-014-2964-0
- Principles of Environmental Physics: Plants, Animals, and the Atmosphere.fourth ed. Academic Press, Oxford2013
- Influence of aerobic fitness on thermoregulation during exercise in the heat.Exerc. Sport Sci. Rev. 2012; 40: 79-87https://doi.org/10.1097/JES.0b013e318246ee56
- Aerobically trained individuals have greater increases in rectal temperature than untrained ones during exercise in the heat at similar relative intensities.Eur. J. Appl. Physiol. 2010; 109: 973-981https://doi.org/10.1007/s00421-010-1436-4
- A comparison between the technical absorbent and ventilated capsule methods for measuring local sweat rate.J. Appl. Physiol. 2013; 114: 816-823https://doi.org/10.1152/japplphysiol.01088.2012
- No differences in cycling efficiency between world-class and recreational cyclists.Int. J. Sports Med. 2004; 25: 374-379https://doi.org/10.1055/s-2004-815848
- Techniques for the measurement of human energy expenditure: a practical guide.Int. J. Obes. Relat. Metab. Disord. 1993; 17: 549-568
- Energy exchanges of swimming man.J. Appl. Physiol. 1974; 36: 465-471
- Peripheral modifications to the central drive for sweating.J. Appl. Physiol. 1971; 31: 828-833
- On the regulation of sweat secretion in exercise.Acta Physiol. Scand. 1965; 64: 314-322
- Die regulation der korpertemperatur bei muskelarbeit.Skand. Arch. Physiol. 1938; 79: 193-230
- Effective temperature scale useful for hypo- and hyperbaric environments.Aviat. Space Environ. Med. 1977; 48: 97-107
- Direct evaluation of convective heat transfer coefficient by naphthalene sublimation.J. Appl. Physiol. 1970; 29: 830-838
- Prediction modeling of physiological responses and human performance in the heat.Comput. Biol. Med. 1986; 16: 319-329
- Human energy expenditure.Physiol. Rev. 1955; 35: 801-840
- Humid heat acclimation does not elicit a preferential sweat redistribution toward the limbs.Am. J. Physiol. Regul. Integr. Comp. Physiol. 2004; 286: R512-R518https://doi.org/10.1152/ajpregu.00359.2003
- Comparing changes in core temperature between groups differing greatly in body morphology during exercise in an uncompensable environment.Med. Sci. Sports Exerc. 2015; 47: 496https://doi.org/10.1249/01.mss.0000466087.31623.98
- Heart rate and body temperature responses to extreme heat and humidity with and without electric fans.JAMA. 2015; 313: 724-725https://doi.org/10.1001/jama.2015.153
- Skin blood flow and sweating changes following exercise training and heat acclimation.J. Appl. Physiol. 1977; 43: 133-137
- Precooling methods and their effects on athletic performance : a systematic review and practical applications.Sports Med. Auckl. NZ. 2013; 43: 207-225https://doi.org/10.1007/s40279-012-0014-9
- Die Gesetze des Energieverbrauchs bei der Ernährung.Deuticker, Lepzig and Vienna1902
- Esophageal, rectal, and muscle temperature during exercise.J. Appl. Physiol. 1966; 21: 1757-1762
- Factors affecting running economy in trained distance runners.Sports Med. 2004; 34: 465-485
- Temperature regulation during upper body exercise: able-bodied and spinal cord injured.Med. Sci. Sports Exerc. 1989; 21: S132-S140
- Absolute power, not sex, promotes perspiration.Exp. Physiol. 2011; 96: 556-558https://doi.org/10.1113/expphysiol.2010.055996
- Responses of obese and non-obese boys cycling in the heat.Int. J. Sports Med. 2012; 33: 497-501https://doi.org/10.1055/s-0031-1301314
- Thermoregulatory sweating in palmar hyperhidrosis before and after upper thoracic sympathectomy.J. Neurosurg. 1979; 50: 88-94https://doi.org/10.3171/jns.1979.50.1.0088
- Physique and heat tolerance in hot-dry and hot-humid environments.J. Appl. Physiol. 1973; 34: 799-803
- Body mapping of sweating patterns in athletes: a sex comparison.Med. Sci. Sports Exerc. 2012; 44: 2350-2361https://doi.org/10.1249/MSS.0b013e318267b0c4
- Body mapping of sweating patterns in male athletes in mild exercise-induced hyperthermia.Eur. J. Appl. Physiol. 2011; 111: 1391-1404https://doi.org/10.1007/s00421-010-1744-8
- Running economy, not aerobic fitness, independently alters thermoregulatory responses during treadmill running.J. Appl. Physiol. 2014; 117 (Bethesda Md 1985): 1451-1459https://doi.org/10.1152/japplphysiol.00665.2014
- External work in level and grade walking on a motor-driven treadmill.J. Appl. Physiol. 1960; 15: 759-763
- Short-term exercise training does not improve whole-body heat loss when rate of metabolic heat production is considered.Eur. J. Appl. Physiol. 2010; 109: 437-446https://doi.org/10.1007/s00421-010-1380-3
- A Mathematical Model of Physiological Temperature Regulation in Man, NASA Contractor Report 1855.J.B. Pierce Laboratory, New Haven, CT1971
- To cool, but not too cool: that is the question–immersion cooling for hyperthermia.Med. Sci. Sports Exerc. 2008; 40: 1962-1969https://doi.org/10.1249/MSS.0b013e31817eee9d
- Human body surface area: measurement and prediction using three dimensional body scans.Eur. J. Appl. Physiol. 2001; 85: 264-271
- Interventions for treating inadvertent postoperative hypothermia.Cochrane Database Syst. Rev. 2014; 11CD009892https://doi.org/10.1002/14651858.CD009892.pub2
- Heat of evaporation of sweat: thermodynamic considerations.J. Appl. Physiol. 1972; 32: 456-459
Article info
Publication history
Published online: March 04, 2016
Accepted:
March 3,
2016
Received in revised form:
March 2,
2016
Received:
October 1,
2015
Identification
Copyright
© 2016 Elsevier B.V. All rights reserved.
