Dissipation of metabolic heat in the horse during exercise.
Abstract: Horses were exercised at 40, 65, and 90% of their maximum O2 uptake (VO2max) until moderately fatigued (approximately 38, 15, and 9 min, respectively) to assess heat loss through different routes. Approximately 4,232, 3,195, and 2,333 kcal of heat were generated in response to exercise at these intensities. Of this, approximately 7, 16, and 20% remained as stored heat 30 min postexercise. Respiratory heat loss, estimated from the temperature difference between blood in the pulmonary and carotid arteries and the cardiac output, was estimated to be 30, 19, and 23% of the heat produced during exercise at the three intensities. The kinetics of the increases in muscle and blood temperature were similar, with the greatest change in temperature occurring in muscle (+3.8, 5.2, and 6.1 degrees C after exercise at 40, 65, and 90% of VO2max, respectively). The temperature of blood in the superficial thoracic vein was approximately 2 degrees C below that of arterial blood at rest. This difference had increased to approximately 3 degrees C during the last minute of exercise. The rate of sweating at sites on the back and neck increased with exercise intensity to a common peak of approximately 40 ml.m-2.min-1. If complete evaporation had occurred, water loss in response to exercise (estimated to be 12, 10, and 7.7 liters for the different intensities of exercise) greatly surpassed that required for dissipation of the metabolic heat load.
Publication Date: 1993-03-01 PubMed ID: 8482654DOI: 10.1152/jappl.1993.74.3.1161Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research article explores how horses manage to dissipate heat generated during different levels of exercise. It particularly focuses on the percentage of heat that is stored and that which is lost through various avenues including respiration and sweating.
Experimental Methodology
- Horses were made to exercise at three different intensities: 40%, 65%, and 90% of their maximum oxygen uptake (VO2max) until they showed moderate signs of fatigue. The durations of these exercise sessions were approximately 38, 15, and 9 minutes respectively.
- For each exercise intensity, the heat generated by the exercising horse was measured. The quantified measures were 4,232 kcal, 3,195 kcal, and 2,333 kcal for the respective exercise intensities.
- Around 30 minutes post-exercise, measurements were taken again to estimate how much of the generated heat had been stored by the horse.
- Respiratory heat loss was calculated by assessing the difference in temperature between the blood in the carotid and pulmonary arteries, with the cardiac output taken into account.
- Changes in both blood and muscle temperatures were recorded, with muscle temperatures presenting the most significant changes.
- The temperature difference between the arterial blood and blood in the superficial thoracic vein was also recorded both at rest and during the last minute of exercise.
- Furthermore, the researchers measured the rate of sweating at the back and neck, particularly their correlation with the intensity of exercise. They also estimated the water lost as a result of exercise, and if fully evaporated, how much it contributes to the dissipation of the metabolic heat load.
Findings and Conclusion
- The research found that 7%, 16%, and 20% of the heat produced from exercising at 40%, 65%, and 90% VO2max, respectively, remained stored in the body 30 minutes after the exercise session.
- Respiratory heat loss was found to be 30%, 19%, and 23% of the total heat produced for each of the respective intensities.
- Regarding changes in temperature, muscle temperatures experienced the greatest change, increasing by 3.8, 5.2, and 6.1 degrees Celsius after exercise at the three intensities.
- The temperature of the blood in the superficial thoracic vein was found to be approximately 2 degrees Celsius lower than that of arterial blood at rest — a difference that increased to approximately 3 degrees Celsius during the last minute of exercise.
- The rate of sweating increased with exercise intensity, peaking at about 40 ml.m-2.min-1. The researchers estimated the total water loss to be 12, 10, and 7.7 liters for each respective exercise intensity.
- The research concluded that if complete evaporation occurred, then the water loss as a result of exercise surpassed what would be required for the dissipation of metabolic heat load.
Cite This Article
APA
Hodgson DR, McCutcheon LJ, Byrd SK, Brown WS, Bayly WM, Brengelmann GL, Gollnick PD.
(1993).
Dissipation of metabolic heat in the horse during exercise.
J Appl Physiol (1985), 74(3), 1161-1170.
https://doi.org/10.1152/jappl.1993.74.3.1161 Publication
Researcher Affiliations
- Department of Veterinary and Comparative Anatomy, College of Veterinary Medicine, Washington State University, Pullman 99164.
MeSH Terms
- Animals
- Blood Physiological Phenomena
- Body Temperature Regulation / physiology
- Body Weight / physiology
- Cardiac Output / physiology
- Horses
- Muscles / physiology
- Oxygen Consumption / physiology
- Physical Exertion / physiology
- Pulmonary Circulation / physiology
- Rectum / physiology
- Skin Temperature / physiology
- Sweating / physiology
Citations
This article has been cited 20 times.- Kang H, Zsoldos RR, Sole-Guitart A, Narayan E, Cawdell-Smith AJ, Gaughan JB. Heat stress in horses: a literature review.. Int J Biometeorol 2023 Jun;67(6):957-973.
- Trigg LE, Lyons S, Mullan S. Risk factors for, and prediction of, exertional heat illness in Thoroughbred racehorses at British racecourses.. Sci Rep 2023 Mar 14;13(1):3063.
- Brownlow M, Mizzi JX. An Overview of Exertional Heat Illness in Thoroughbred Racehorses: Pathophysiology, Diagnosis, and Treatment Rationale.. Animals (Basel) 2023 Feb 9;13(4).
- Cox EG, Bell R, Greer RM, Jeffcott LB. A survey on the use of rugs in Australian horses.. Aust Vet J 2023 Jan;101(1-2):9-26.
- Sponseller BT, Wong DM, Ruby R, Ware WA, Wilson S, Haynes JS. Systemic calcinosis in a Quarter Horse gelding homozygous for a myosin heavy chain 1 mutation.. J Vet Intern Med 2022 Jul;36(4):1543-1549.
- Verdegaal EJMM, Howarth GS, McWhorter TJ, Delesalle CJG. Is Continuous Monitoring of Skin Surface Temperature a Reliable Proxy to Assess the Thermoregulatory Response in Endurance Horses During Field Exercise?. Front Vet Sci 2022;9:894146.
- Kang H, Zsoldos RR, Skinner JE, Gaughan JB, Mellor VA, Sole-Guitart A. The Use of Percutaneous Thermal Sensing Microchips to Measure Body Temperature in Horses during and after Exercise Using Three Different Cool-Down Methods.. Animals (Basel) 2022 May 14;12(10).
- Verdegaal EJMM, Howarth GS, McWhorter TJ, Boshuizen B, Franklin SH, Vidal Moreno de Vega C, Jonas SE, Folwell LE, Delesalle CJG. Continuous Monitoring of the Thermoregulatory Response in Endurance Horses and Trotter Horses During Field Exercise: Baselining for Future Hot Weather Studies.. Front Physiol 2021;12:708737.
- Maśko M, Witkowska-Piłaszewicz O, Jasiński T, Domino M. Thermal features, ambient temperature and hair coat lengths: Limitations of infrared imaging in pregnant primitive breed mares within a year.. Reprod Domest Anim 2021 Oct;56(10):1315-1328.
- Maśko M, Zdrojkowski Ł, Wierzbicka M, Domino M. Association between the Area of the Highest Flank Temperature and Concentrations of Reproductive Hormones during Pregnancy in Polish Konik Horses-A Preliminary Study.. Animals (Basel) 2021 May 23;11(6).
- Klous L, Siegers E, van den Broek J, Folkerts M, Gerrett N, van Oldruitenborgh-Oosterbaan MS, Munsters C. Effects of Pre-Cooling on Thermophysiological Responses in Elite Eventing Horses.. Animals (Basel) 2020 Sep 16;10(9).
- Soroko M, Śpitalniak-Bajerska K, Zaborski D, Poźniak B, Dudek K, Janczarek I. Exercise-induced changes in skin temperature and blood parameters in horses.. Arch Anim Breed 2019;62(1):205-213.
- Stephens-Brown L, Davis M. Water requirements of canine athletes during multi-day exercise.. J Vet Intern Med 2018 May;32(3):1149-1154.
- McNicholl J, Howarth GS, Hazel SJ. Influence of the Environment on Body Temperature of Racing Greyhounds.. Front Vet Sci 2016;3:53.
- Stefánsdóttir GJ, Ragnarsson S, Gunnarsson V, Jansson A. Physiological response to a breed evaluation field test in Icelandic horses.. Animal 2014 Mar;8(3):431-9.
- Castejón-Riber C, Muñoz A, Trigo P, Riber C, Santisteban R, Castejón F. Comparative ergoespirometric adaptations to a treadmill exercise test in untrained show Andalusian and Arabian horses.. Vet Res Commun 2012 Mar;36(1):41-6.
- Mealey RH, Littke MH, Leib SR, Davis WC, McGuire TC. Failure of low-dose recombinant human IL-2 to support the survival of virus-specific CTL clones infused into severe combined immunodeficient foals: lack of correlation between in vitro activity and in vivo efficacy.. Vet Immunol Immunopathol 2008 Jan 15;121(1-2):8-22.
- Gillooly JF, Allen AP. Changes in body temperature influence the scaling of VO2max and aerobic scope in mammals.. Biol Lett 2007 Feb 22;3(1):99-102.
- Mills PC, Marlin DJ, Demoncheaux E, Scott C, Casas I, Smith NC, Higenbottam T. Nitric oxide and exercise in the horse.. J Physiol 1996 Sep 15;495 ( Pt 3)(Pt 3):863-74.
- Gauvreau GM, Young SS, Staempfli H, McCutcheon LJ, Wilson BA, McDonell WN. The relationship between respiratory exchange ratio, plasma lactate and muscle lactate concentrations in exercising horses using a valved gas collection system.. Can J Vet Res 1996 Jul;60(3):161-71.
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