Thermoregulation during Exercise in the Heat

Strategies for Maintaining Health and Performance

Abstract

As a result of the inefficiency of metabolic transfer, >75% of the energy that is generated by skeletal muscle substrate oxidation is liberated as heat. During exercise, several powerful physiological mechanisms of heat loss are activated to prevent an excessive rise in body core temperature. However, a hot and humid environment can significantly add to the challenge that physical exercise imposes on the human thermoregulatory system, as heat exchange between body and environment is substantially impaired under these conditions. This can lead to serious performance decrements and an increased risk of developing heat illness. Fortunately, there are a number of strategies that athletes can use to prevent and/or reduce the dangers that are associated with exercise in the heat. In this regard, heat acclimatisation and nutritional intervention seem to be most effective. During heat acclimatisation, the temperature thresholds for both cutaneous vasodilation and the onset of sweating are lowered, which, in combination with plasma volume expansion, improve cardiovascular stability. Effective nutritional interventions include the optimisation of hydration status by the use of fluid replacement beverages. The latter should contain moderate amounts of glucose and sodium, which improve both water absorption and retention.

This is a preview of subscription content, access via your institution.

Table I
Table II

References

  1. 1.

    Guyton AC, Hall JE. Textbook of medical physiology. Philadelphia (PA): Saunders Company, 1996

    Google Scholar 

  2. 2.

    Nadel ER. Temperature regulation and hyperthermia during exercise. Clin Chest Med 1984; 5: 13–20

    PubMed  CAS  Google Scholar 

  3. 3.

    Cheuvront SN, Haymes EM. Thermoregulation and marathon running. Sports Med 2001; 31: 743–62

    PubMed  Article  CAS  Google Scholar 

  4. 4.

    Brooks GA, Fahey TD, White TP. Exercise physiology: human bioenergetics and its applications. Mountain View (CA): Mayfield Publishing Company, 1996

  5. 5.

    Gleeson M. Temperature regulation during exercise. Int J Sports Med 1998; 19: 96–9

    Article  Google Scholar 

  6. 6.

    Cooper KE. Some historical perspectives on thermoregulation. J Appl Physiol 2002; 92: 1717–24

    PubMed  CAS  Google Scholar 

  7. 7.

    Boulant JA. Hypothalamic neurons regulating body temperature. In: Fregly MJ, Blatteis CM, editors. Handbook of physibody New York: Oxford Press, 1996: 105–26

    Google Scholar 

  8. 8.

    Boulant JA. Role of the preoptic-anterior hypothalamus in thermoregulation and fever. Clin Infect Dis 2000; 31 Suppl. 5: S157–61

    Article  Google Scholar 

  9. 9.

    Benzinger TH. Heat regulation: homeostasis of central temperature in man. Physiol Rev 1969; 49: 671–759

    PubMed  CAS  Google Scholar 

  10. 10.

    Cheung SS, McLellan TM, Tenaglia S. The thermophysiology of uncompensable heat stress. Sports Med 2000; 29: 329–59

    PubMed  Article  CAS  Google Scholar 

  11. 11.

    Kellogg DL, Johnson JM, Kosiba WA. Control of internal temperature threshold for active cutaneous vasodilation by dynamic exercise. J Appl Physiol 1991; 71: 2476–82

    PubMed  Google Scholar 

  12. 12.

    Kenney WL, Johnson JM. Control of skin blood flow during exercise. Med Sci Sports Exerc 1992; 24: 303–12

    PubMed  CAS  Google Scholar 

  13. 13.

    Kellogg DL, Johnson JM, Kenney WL, et al. Mechanisms of control of skin blood flow during prolonged exercise in humans. Am J Physiol 1993; 265: H562–8

    PubMed  Google Scholar 

  14. 14.

    Kellogg DL, Pérgola PE, Kosiba WA, et al. Cutaneous active vasodilation in humans is mediated by cholinergic nerve cotransmission. Circ Res 1995; 77: 1222–8

    PubMed  Article  CAS  Google Scholar 

  15. 15.

    Kellogg DL, Johnson JM, Kosiba WA. Competition between cutaneous active vasoconstriction and active vasodilation during exercise in humans. Am J Physiol 1991; 261: H1184–9

    PubMed  Google Scholar 

  16. 16.

    Kellogg DL, Johnson JM, Kosiba WA. Baroreflex control of the quires the ingestion of 200–300mL of fluid every cutaneous active vasodilator system in humans. Circ Res 1990; 66: 1420–6

    PubMed  Article  Google Scholar 

  17. 17.

    Mack GW, Nishiyasu T, Shi X. Baroreceptor modulation of cutaneous vasodilator and sudomotor responses to thermal stress in humans. J Physiol 1995; 483: 537–47

    PubMed  CAS  Google Scholar 

  18. 18.

    Crandall CG, Johnson JM, Kosiba WA, et al. Baroreceptor control of the cutaneous active vasodilator sytem. J Appl Physiol 1996; 81: 2192–8

    PubMed  CAS  Google Scholar 

  19. 19.

    Mack GW, Cordero D, Peters J. Baroreceptor modulation of active cutaneous vasodilation during dynamic exercise in humans. J Appl Physiol 2001; 90: 1464–73

    PubMed  CAS  Google Scholar 

  20. 20.

    Allan JR, Wilson CG. Influence of acclimatization on sweat sodium concentration. J Appl Physiol 1971; 30: 708–12

    PubMed  CAS  Google Scholar 

  21. 21.

    Sawka MN, Montain SJ. Fluid and electrolyte supplementation for exercise heat stress. Am J Clin Nutr 2000; 72: S564–72

    Google Scholar 

  22. 22.

    Yaqub B, Al Deeb S. Heat strokes: aetiopathogenesis, neurological characteristics, treatment and outcome. J Neurol Sci 1998; 156: 144–51

    PubMed  Article  CAS  Google Scholar 

  23. 23.

    Sawka MN. Physiological consequences of hypohydration: exercise performance and thermoregulation. Med Sci Sports Ex 1992; 24: 657–70

    CAS  Google Scholar 

  24. 24.

    Sawka MN, Young AJ, Francesconi RP, et al. Thermoregulatory and blood responses during exercise at graded hypohydration levels. J Appl Physiol 1985; 59: 1394–1440

    PubMed  CAS  Google Scholar 

  25. 25.

    Fortney SM, Wenger CB, Bove JR, et al. Effect of hyperosmolality on control of blood flow and sweating. J Appl Physiol 1984; 57: 1688–95

    PubMed  CAS  Google Scholar 

  26. 26.

    Takamata A, Nagashima K, Nose H, et al. Osmoregulatory inhibition of thermally induced cutaneous vasodilation in passively heated humans. Am J Physiol 1997; 273: R197–204

    PubMed  CAS  Google Scholar 

  27. 27.

    Silva NL, Boulant JA. Effects of osmotic pressure, glucose and temperature on neurons in preoptic tissue slices. Am J Physiol 1984; 247: R335–45

    PubMed  CAS  Google Scholar 

  28. 28.

    Nakashima T, Hori T, Kiyohara T, et al. Osmosensitivity of preoptic thermosensitive neurons in hypothalamic slices in vitro. Eur J Physiol 1985; 405: 112–7

    Article  CAS  Google Scholar 

  29. 29.

    Talbot HT. Heat cramps. Medicine 1935; 14: 323–76

    Article  Google Scholar 

  30. 30.

    Schwellnus MP, Derman EW, Noakes TD. Aetiology of skeletal muscle ‘cramps’ during exercise: a novel hypothesis. J Sports Sci 1997; 15: 277–85

    PubMed  Article  CAS  Google Scholar 

  31. 31.

    Noakes TD. Fluid and electrolyte disturbances in heat illness. Int J Sports Med 1998; 19: S146–9

    PubMed  Article  Google Scholar 

  32. 32.

    Holtzhausen LM, Noakes TD, Kroning B, et al. Clinical and biochemical characteristics of collapsed ultramarathon runners. Med Sci Sports Exerc 1994; 26: 1095–101

    PubMed  CAS  Google Scholar 

  33. 33.

    Bouchama A, Knochel JP. Heat stroke. N Engl J Med 2002; 346: 1978–88

    PubMed  Article  CAS  Google Scholar 

  34. 34.

    Hales JRS. Hyperthermia and heat illness. Pathophysiological implications for avoidance and treatment. Ann NY Acad Sci 1997; 813: 534–44

    PubMed  Article  CAS  Google Scholar 

  35. 35.

    Hall DM, Baumgardner KR, Oberley TD, et al. Splanchnic tissues undergo hypoxic stress during whole body hyperthermia. Am J Physiol Gastroistest Liver Physiol 1999; 276: G1195–203

    CAS  Google Scholar 

  36. 36.

    Hall DM, Buettner GR, Oberley LW, et al. Mechanisms of circulatory and intestinal barrier dysfunction during whole body hyperthermia. Am J Physiol Heart Circ Physiol 2001; 280: H509–21

    PubMed  CAS  Google Scholar 

  37. 37.

    Gonzalez-Alonso J, Teller C, Andersen SL, et al. Influence of body temperature on the development of fatigue during prolonged exercise in the heat. Am J Physiol 1999; 86: 1032–9

    CAS  Google Scholar 

  38. 38.

    Cheung SS, Sleivert GG. Multiple triggers for hyperthermic fatigue and exhaustion. Exerc Sport Sci Rev 2004; 32: 100–6

    PubMed  Article  Google Scholar 

  39. 39.

    Daanen HA, van Es EM, de Graaf JL. Heat strain and gross efficiency during endurance exercise after lower, upper or wholebody precooling in the heat. Int J Sports Med 2005; 26: 1–10

    Article  Google Scholar 

  40. 40.

    Marino FE. Methods, advantages, and limitations of body cooling for exercise performance. Br J Sports Med 2002; 36: 89–94

    PubMed  Article  CAS  Google Scholar 

  41. 41.

    Sawka MN, Montain SJ, Latzka WA. Hydration effects on thermoregulation and performance in the heat. Comp Biochem Physiol 2001; 128: 679–90

    Article  CAS  Google Scholar 

  42. 42.

    Lyons TP, Riedesel ML, Meuli LE, et al. Effects of glycerol-induced hyperhydration prior to exercise in the heat on sweating and core temperature. Med Sci Sports Exerc 1990; 22: 477–83

    PubMed  CAS  Google Scholar 

  43. 43.

    Montner P, Stark DM, Riedesel ML, et al. Pre-exercise glycerol hydration improves cycling endurance time. Int J Sports Med 1996; 17: 27–33

    PubMed  Article  CAS  Google Scholar 

  44. 44.

    Latzka WA, Sawka MN, Montain SJ. Hyperhydration: tolerance and cardiovascular effects during uncompensable exercise heat stress. J Appl Physiol 1998; 84: 1858–63

    PubMed  CAS  Google Scholar 

  45. 45.

    Maughan RJ, Shirreffs SM. Exercise in the heat: challenges and opportunities. J Sports Sci 2004; 22: 917–27

    PubMed  Article  Google Scholar 

  46. 46.

    Gavin TP. Clothing and thermoregulation during exercise. Sports Med 2003; 33: 941–7

    PubMed  Article  Google Scholar 

  47. 47.

    Armstrong LE, Maresh CM. The induction and decay of heat acclimatisation in trained athletes. Sports Med 1991; 12: 302–12

    PubMed  Article  CAS  Google Scholar 

  48. 48.

    Nielsen B, Hales JRS, Strange S, et al. Human circulatory and thermoregulatory adaptations with heat acclimatisation and exercise in a hot dry environment. J Physiol 1993; 460: 467–85

    PubMed  CAS  Google Scholar 

  49. 49.

    Patterson MJ, Stocks JM, Taylor NAS. Sustained and generalized extracellular fluid expansion following heat acclimatisation. J Physiol 2004; 559: 327–34

    PubMed  Article  CAS  Google Scholar 

  50. 50.

    Armstrong LE, Hubbard RW, Askew EW, et al. Responses to moderate and low sodium diets during exercise-heat acclimation. Int J Sport Nutr 1993; 3: 207–21

    PubMed  CAS  Google Scholar 

  51. 51.

    Luetkemeier MJ. Dietary sodium intake and changes in plasma volume during short-term exercise training. Int J Sports Med Sci 1997; 15: 277–85

    Google Scholar 

  52. 52.

    Luetkemeier MJ, Flowers KM, Lamb DR. Spironolactone administration and training-induced hypervolemia. Int J Sports Med 1994; 15: 295–300

    PubMed  Article  CAS  Google Scholar 

  53. 53.

    Convertino VA, Mack GW, Nadel ER. Elevated central venous pressure: a consequence of exercise-training induced hypervolemia? Am J Physiol 1991; 260: R273–7

    PubMed  CAS  Google Scholar 

  54. 54.

    Yamazaki F, Hamasaki K. Heat acclimatisation increases skin vasodilation and sweating but not cardiac baroreflex responses in heat-stressed humans. J Appl Physiol 2003; 95: 1567–74

    PubMed  Google Scholar 

  55. 55.

    Pandolf KB. Time course of heat acclimation and its decay. Int J Sports Med 1998; 19: S157–60

    PubMed  Article  Google Scholar 

  56. 56.

    Fein LW, Haymes EM, Buskirk ER. Effects of daily and intermittent exposure on heat acclimation of women. Int J Biomet 1975; 19: 41–52

    Article  CAS  Google Scholar 

  57. 57.

    Lind AR, Bass DE. Optimal exposure time for development of heat acclimation. Fed Proc 1963; 22: 704–8

    PubMed  CAS  Google Scholar 

  58. 58.

    Gisolfi CV, Summers RD, Schedl HP, et al. Effect of sodium concentration in a carbohydrate-electrolyte solution on intestinal absorption. Med Sci Sports Exerc 1995; 27: 1414–20

    PubMed  CAS  Google Scholar 

  59. 59.

    Gisolfi CV, Duchman SM. Guidelines for optimal replacement beverages for different athletic events. Med Sci Sports Exerc 1992; 24: 679–87

    PubMed  CAS  Google Scholar 

  60. 60.

    Brouns F. Gastric emptying as a regulatory factor in fluid uptake. Int J Sports Med 1998; 19: S125–8

    PubMed  Article  Google Scholar 

  61. 61.

    Vist GE, Maughan RJ. The effect of osmolality and carbohydrate content on the rate of gastric emptying of liquids in man. J Physiol 1995; 486: 523–31

    PubMed  CAS  Google Scholar 

  62. 62.

    Leiper JB. Intestinal water absorption: implications for the formulation of rehydration solutions. Int J Sports Med 1998; 19: S129–32

    PubMed  Article  CAS  Google Scholar 

  63. 63.

    Murray R. The effects of consuming carbohydrate-electrolyte beverages on gastric emptying and fluid absorption during and following exercise. Sports Med 1987; 4: 322–51

    PubMed  Article  CAS  Google Scholar 

  64. 64.

    Madara JL, Pappenheimer JR. Structural basis for physiological regulation of paracellular pathways in intestinal epithelia. J Membrane Biol 1987; 100: 149–64

    Article  CAS  Google Scholar 

  65. 65.

    Pappenheimer JR. Paracellular intestinal absorption of glucose, creatinine, and mannitol in normal animals: relation to body size. Am J Physiol 1990; 259: G290–9

    PubMed  CAS  Google Scholar 

  66. 66.

    Maughan RJ, Leiper JB. Effects of sodium content of ingested fluids on post-exercise rehydration in man. Eur J Appl Physiol 1995; 71: 311–9

    Article  CAS  Google Scholar 

  67. 67.

    Shirreffs SM, Taylor AJ, Leiper JB, et al. Post-exercise rehydration in man: effect of volume consumed and drink sodium content. Med Sci Sports Exerc 1996; 28: 1260–71

    PubMed  Article  CAS  Google Scholar 

  68. 68.

    Convertino VA, Armstrong LE, Coyle EF, et al. American College of Sports Medicine position stand: exercise and fluid replacement. Med Sci Sports Exerc 1996; 28: i–vi

    PubMed  Article  CAS  Google Scholar 

  69. 69.

    Casa DJ, Armstrong LE, Hillman SK, et al. National athletic trainers’ association position statement: fluid replacement for athletes. J Athl Train 2000; 35: 212–24

    PubMed  CAS  Google Scholar 

  70. 70.

    Maughan RJ, Leiper JB, Vist GE. Gastric emptying and fluid availability after ingestion of glucose and soy protein hydrolysate solutions in man. Exp Physiol 2003; 89: 101–8

    Article  Google Scholar 

  71. 71.

    Coyle EF. Fluid and fuel intake during exercise. J Sports Sci 2004; 22: 39–55

    PubMed  Article  Google Scholar 

  72. 72.

    Murray R. Rehydration strategies: balancing substrate, fluid, and electrolyte provision. Int J Sports Med 1998; 19: S133–5

    PubMed  Article  CAS  Google Scholar 

  73. 73.

    Shi X, Summers RW, Schedl HP, et al. Effects of carbohydrate type and concentration and solution osmolality on water absorption. Med Sci Sports Exerc 1995; 27: 1607–15

    PubMed  CAS  Google Scholar 

  74. 74.

    Leiper JB, Brouns F, Maughan RJ. Effects of variation in the type of carbohydrate on absortion from hypotonic carbohydrate electrolyte solutions (CES) in the human jejunal perfusion model. J Physiol 1996; 495: 128

    Google Scholar 

  75. 75.

    Shirreffs SM, Maughan RJ. Volume repletion after exercise-induced volume depletion in humans: replacement of water and sodium losses. Am J Physiol 1998; 274: F868–75

    PubMed  CAS  Google Scholar 

  76. 76.

    Maughan RJ, Shirreffs SM. Recovery from prolonged exercise: restoration of water and electrolyte balance. J Sports Sci 1997; 15: 297–303

    PubMed  Article  CAS  Google Scholar 

  77. 77.

    Armstrong LE. Hydration assessment techniques. Nutr Rev 2005; 63: S40–54

    PubMed  Article  Google Scholar 

Download references

Acknowledgements

No funding was received in the preparation of this article. The author has no potential conflicts of interest directly releveant to the contents of this article

Author information

Affiliations

Authors

Corresponding author

Correspondence to Dr Wouter D. Marken Lichtenbelt.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Wendt, D., van Loon, L.J. & Marken Lichtenbelt, W.D. Thermoregulation during Exercise in the Heat. Sports Med 37, 669–682 (2007). https://doi.org/10.2165/00007256-200737080-00002

Download citation

Keywords

  • Body Core Temperature
  • Sweat Rate
  • Heat Stroke
  • Lower Body Negative Pressure
  • Heat Acclimatisation