Effect of high ambient temperature on physiological responses during incremental exercise in Thoroughbred horses
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Several reports have suggested that the risk of exertional heat illness (EHI) in Thoroughbred racehorses increases in high ambient temperatures. Heat dissipation in horses during exercise becomes less efficient when the body temperature and ambient temperature are close. Therefore, we hypothesised that exercise at 40 °C may increase body temperature, oxygen consumption, and cardiac output during incremental exercise tests compared to 20 and 30 °C. Six trained Thoroughbred horses were studied in a randomised, crossover design at three ambient temperatures with a 6-day washout period. Using a 3% inclined treadmill, horses performed incremental exercise tests at 1.7, 3.5, 6, 8, and 10 m/s for 90 s at ambient temperatures of 20, 30, and 40 °C. The effects of ambient temperature at 10 m/s on physiological variables were analysed using mixed models (P<0.05). Pulmonary arterial temperature and rectal temperature at 40 °C were higher than those at 20 °C (P<0.001) and 30 °C (P<0.001). Similarly, oxygen consumption (vs 20 °C, P=0.009; vs 30 °C, P=0.006) and cardiac output (vs 20 °C, P=0.001; vs 30 °C, P=0.001) at 40 °C were higher than those at 20 and 30 °C. Arterial O2 partial pressure, O2 saturation, and pH at 40 °C were lower than those at 20 and 30 °C. Arterial CO2 partial pressure at 40 °C was higher than that at 20 and 30 °C. No differences were observed in arterial-mixed venous O2 concentration difference (P=0.391) and plasma lactate concentration (P=0.134) at different ambient temperatures. These results indicate that exercise at 40 °C causes excessive high body temperature, decreased running economy, and increased cardiac output compared to exercise at 20 and 30 °C. We strongly suggest that trainers and veterinarians should anticipate the occurrence of increased thermal stresses when ambient temperature is extremely high even in dry conditions and prepare to mitigate the risk of EHI from the perspective of equine welfare.
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-
Art, T., Anderson, L., Woakes, A.J., Roberts, C., Butler, P.J., Snow, D.H. and Lekeux, P., 1990. Mechanics of breathing during strenuous exercise in Thoroughbred horses. Respiration Physiology 82: 279-294. https://doi.org/10.1016/0034-5687(90)90098-j
-
Art, T. and Lekeux, P., 1995. Respiratory adjustments in unacclimatised horses exercised under hot, humid conditions. Equine Veterinary Journal 27 Suppl. 18: 289-293. https://doi.org/10.1111/j.2042-3306.1995.tb04939.x
-
Barnes, K.R. and Kilding, A.E., 2015. Running economy: measurement, norms, and determining factors. Sports Medicine Open 1: 8. https://doi.org/10.1186/s40798-015-0007-y
-
Bayly, W.M., Hodgson, D.R., Schulz, D.A., Dempsey, J.A. and Gollnick, P.D., 1989. Exercise-induced hypercapnia in the horse. Journal of Applied Physiology 67: 1958-1966. https://doi.org/10.1152/jappl.1989.67.5.1958
-
Birks, E.K., Ohmura, H. and Jones, J.H., 2019. Measuring VO2 in hypoxic and hyperoxic conditions using dynamic gas mixing with a flow-through indirect calorimeter. Journal of Equine Science 30: 87-92. https://doi.org/10.1294/jes.30.87
-
Brooks, G.A., Hittelman, K.J., Faulkner, J.A. and Beyer, R.E., 1971. Temperature, skeletal muscle mitochondrial functions, and oxygen debt. American Journal of Physiology 220: 1053-1059. https://doi.org/10.1152/ajplegacy.1971.220.4.1053
-
Brownlow, M.A., Dart, A.J. and Jeffcott, L.B., 2016. Exertional heat illness: a review of the syndrome affecting racing Thoroughbreds in hot and humid climates. Australian Veteterinary Journal 94: 240-247. https://doi.org/10.1111/avj.12454
-
Butler, P.J., Woakes, A.J., Smale, K., Roberts, C.A., Hillidge, C.J., Snow, D.H. and Marlin, D.J., 1993. Respiratory and cardiovascular adjustments during exercise of increasing intensity and during recovery in thoroughbred racehorses. Journal of Experimental Biology 179: 159-180. https://doi.org/10.1242/jeb.179.1.159
-
Casa, D.J., DeMartini, J.K., Bergeron, M.F., Csillan, D., Eichner, E.R., Lopez, R.M., Ferrara, M.S., Miller, K.C., O’Connor, F., Sawka, M.N. and Yeargin, S.W., 2015. National athletic trainers’ association position statement: exertional heat illnesses. Journal of Athletic Training 50: 986-1000.
'National athletic trainers’ association position statement: exertional heat illnesses ' () 50 Journal of Athletic Training : 986 -1000.
-
Cheuvront, S.N., Kenefick, R.W., Montain, S.J. and Sawka, M.N., 2010. Mechanisms of aerobic performance impairment with heat stress and dehydration. Journal of Applied Physiology 109: 1989-1995.
'Mechanisms of aerobic performance impairment with heat stress and dehydration ' () 109 Journal of Applied Physiology : 1989 -1995.
-
Cooper, E.R., Ferrara, M.S., Casa, D.J., Powell, J.W., Broglio, S.P., Resch, J.E. and Courson, R.W., 2016. Exertional heat illness in American football players: when is the risk greatest? Journal of Athletic Training 51: 593-600. https://doi.org/10.4085/1062-6050-51.8.08
-
Davis, M.S., Fulton, M.R. and Popken, A., 2021. Effect of hyperthermia and acidosis on equine skeletal muscle mitochondrial oxygen consumption. Comparative Exercise Physiology 17: 171-179. https://doi.org/10.3920/CEP200041
-
Evans, D.L. and Rose, R.J., 1988. Cardiovascular and respiratory responses in Thoroughbred horses during treadmill exercise. Journal of Experimental Biology 134: 397-408. https://doi.org/10.1242/jeb.134.1.397
-
Fedak, M.A., Rome, L. and Seeherman, H.J., 1981. One-step N2-dilution technique for calibrating open-circuit VO2 measuring systems. Journal of Applied Physiology 51: 772-776. https://doi.org/10.1152/jappl.1981.51.3.772
-
Geor, R.J., McCutcheon, L.J., Ecker, G.L. and Lindinger, M.I., 1995. Thermal and cardiorespiratory responses of horses to submaximal exercise under hot and humid conditions. Equine Veterinary Journal 27 Suppl. 20: 125-132.
'Thermal and cardiorespiratory responses of horses to submaximal exercise under hot and humid conditions ' () 27 Equine Veterinary Journal : 125 -132.
-
Gonzalez-Alonso, J., Crandall, C.G. and Johnson, J.M., 2008. The cardiovascular challenge of exercising in the heat. Journal of Physiology 586: 45-53. https://doi.org/10.1113/jphysiol.2007.142158
-
Hayashi, K., Honda, Y., Ogawa, T., Kondo, N. and Nishiyasu, T., 2006. Relationship between ventilatory response and body temperature during prolonged submaximal exercise. Journal of Applied Physiology 100: 414-420. https://doi.org/10.1152/japplphysiol.00541.2005
-
Hodgson, D.R., 2014. Thermoregulation. In: Hodgson, D.R., McKeever, K.H. and McGowan, C.M. (eds.), The athletic horse; principles and practice of equine sports medicine. Saunders-Elsevier, St Louis, MO, USA, pp. 108-124.
'Thermoregulation ', () 108 -124.
-
Hodgson, D.R., McCutcheon, L.J., Byrd, S.K., Brown, W.S., Bayly, W.M., Brengelmann, G.L. and Gollnick, P.D., 1993. Dissipation of metabolic heat in the horse during exercise. Journal of Applied Physiology 74: 1161-1170. https://doi.org/10.1152/jappl.1993.74.3.1161
-
Johnson, J.M. and Park, M.K., 1982. Effect of heat stress on cutaneous vascular responses to the initiation of exercise. Journal of Applied Pphysiology 53: 744-749. https://doi.org/10.1152/jappl.1982.53.3.744
-
Jones, J.H., Longworth, K.E., Lindholm, A., Conley, K.E., Karas, R.H., Kayar, S.R. and Taylor, C.R., 1989. Oxygen transport during exercise in large mammals. I. Adaptive variation in oxygen demand. Journal of Applied Physiology 67: 862-870. https://doi.org/10.1152/jappl.1989.67.2.862
-
Kellogg Jr., D.L., Johnson, J.M. and Kosiba, W.A., 1991. Control of internal temperature threshold for active cutaneous vasodilation by dynamic exercise. Journal of Applied Physiology 71: 2476-2482. https://doi.org/10.1152/jappl.1991.71.6.2476
-
Kohn, C.W. and Hinchcliff, K.W., 1995. Physiological responses to the endurance test of a 3-day-event during hot and cool weather. Equine Veterinary Journal 27 Suppl. 20: 31-36. https://doi.org/10.1111/j.2042-3306.1995.tb05005.x
-
Lind, A.R., 1963. A physiological criterion for setting thermal environmental limits for everyday work. Journal of Applied Physiology 18: 51-56. https://doi.org/10.1152/jappl.1963.18.1.51
-
MacDougall, J.D., Reddan, W.G., Layton, C.R. and Dempsey, J.A., 1974. Effects of metabolic hyperthermia on performance during heavy prolonged exercise. Journal of Applied Physiology 36: 538-544. https://doi.org/10.1152/jappl.1974.36.5.538
-
Marlin, D.J., Scott, C.M., Schroter, R.C., Mills, P.C., Harris, R.C., Harris, P.A., Orme, C.E., Roberts, C.A., Marr, C.M., Dyson, S.J. and Barrelet, F., 1996. Physiological responses in nonheat acclimated horses performing treadmill exercise in cool (20 degrees C/40% RH), hot dry (30 degrees C/40% RH) and hot humid (30 degrees C/80% RH) conditions. Equine Veterinary Journal 28 Suppl. 22: 70-84. https://doi.org/10.1111/j.2042-3306.1996.tb05034.x
-
McConaghy, F.F., Hales, J.R., Rose, R.J. and Hodgson, D.R., 1995. Selective brain cooling in the horse during exercise and environmental heat stress. Journal of Applied Physiology 79: 1849-1854. https://doi.org/10.1152/jappl.1995.79.6.1849
-
McDonough, P., Kindig, C.A., Erickson, H.H. and Poole, D.C., 2002. Mechanistic basis for the gas exchange threshold in Thoroughbred horses. Journal of Applied Physiology 92: 1499-1505. https://doi.org/10.1152/japplphysiol.00909.2001
-
Mukai, K., Ohmura, H., Matsui, A., Aida, H., Takahashi, T. and Jones, J.H., 2020. High-intensity training in normobaric hypoxia enhances exercise performance and aerobic capacity in Thoroughbred horses: A randomized crossover study. Physiological Reports 8: e14442. https://doi.org/10.14814/phy2.14442
-
National Oceanic and Atmospheric Administration, 2021. Global Climate Report-Annual 2020. Available at: https://www.ncdc.noaa.gov/sotc/global/202013.
-
No, M. and Kwak, H.B., 2016. Effects of environmental temperature on physiological responses during submaximal and maximal exercises in soccer players. Integrative Medicine Research 5: 216-222. https://doi.org/10.1016/j.imr.2016.06.002
-
Nomura, M., Shiose, T., Ishikawa, Y., Mizobe, F., Sakai, S. and Kusano, K., 2019. Prevalence of post-race exertional heat illness in Thoroughbred racehorses and climate conditions at racecourses in Japan. Journal of Equine Science 30: 17-23. https://doi.org/10.1294/jes.30.17
-
Parkin, J.M., Carey, M.F., Zhao, S. and Febbraio, M.A., 1999. Effect of ambient temperature on human skeletal muscle metabolism during fatiguing submaximal exercise. Journal of Applied Physiology 86: 902-908. https://doi.org/10.1152/jappl.1999.86.3.902
-
Periard, J.D., Eijsvogels, T.M.H. and Daanen, H.A.M., 2021. Exercise under heat stress: thermoregulation, hydration, performance implications, and mitigation strategies. Physiological Reviews 101: 1873-1979. https://doi.org/10.1152/physrev.00038.2020
-
Rowell, L.B., 1974. Human cardiovascular adjustments to exercise and thermal stress. Physiological Reviews 54: 75-159. https://doi.org/10.1152/physrev.1974.54.1.75
-
Rowell, L.B., Murray, J.A., Brengelmann, G.L. and Kraning 2nd, K.K., 1969. Human cardiovascular adjustments to rapid changes in skin temperature during exercise. Circulation Research 24: 711-724. https://doi.org/10.1161/01.res.24.5.711
-
Sawka, M.N., 1992. Physiological consequences of hypohydration. Medicine and Science in Sports and Exercise 24: 657-670. https://doi.org/10.1249/00005768-199206000-00008
-
Takahashi, Y. and Takahashi, T., 2020. Risk factors for exertional heat illness in Thoroughbred racehorses in flat races in Japan (2005-2016). Equine Veterinary Journal 52: 364-368. https://doi.org/10.1111/evj.13179
-
Wagner, P.D., Gillespie, J.R., Landgren, G.L., Fedde, M.R., Jones, B.W., DeBowes, R.M., Pieschl, R.L. and Erickson, H.H., 1989. Mechanism of exercise-induced hypoxemia in horses. Journal of Applied Physiology 66: 1227-1233. https://doi.org/10.1152/jappl.1989.66.3.1227
-
Willis, W.T. and Jackman, M.R., 1994. Mitochondrial function during heavy exercise. Medicine and Science in Sports and Exercise 26: 1347-1353. https://doi.org/10.1249/00005768-199411000-00009
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Effect of high ambient temperature on physiological responses during incremental exercise in Thoroughbred horses
In: Comparative Exercise PhysiologySearch for other papers by Y. Ebisuda in
Current site
Google Scholar
PubMed
Search for other papers by K. Mukai in
Current site
Google Scholar
PubMed
Search for other papers by Y. Takahashi in
Current site
Google Scholar
PubMed
Search for other papers by H. Ohmura in
Current site
Google Scholar
PubMed
Several reports have suggested that the risk of exertional heat illness (EHI) in Thoroughbred racehorses increases in high ambient temperatures. Heat dissipation in horses during exercise becomes less efficient when the body temperature and ambient temperature are close. Therefore, we hypothesised that exercise at 40 °C may increase body temperature, oxygen consumption, and cardiac output during incremental exercise tests compared to 20 and 30 °C. Six trained Thoroughbred horses were studied in a randomised, crossover design at three ambient temperatures with a 6-day washout period. Using a 3% inclined treadmill, horses performed incremental exercise tests at 1.7, 3.5, 6, 8, and 10 m/s for 90 s at ambient temperatures of 20, 30, and 40 °C. The effects of ambient temperature at 10 m/s on physiological variables were analysed using mixed models (P<0.05). Pulmonary arterial temperature and rectal temperature at 40 °C were higher than those at 20 °C (P<0.001) and 30 °C (P<0.001). Similarly, oxygen consumption (vs 20 °C, P=0.009; vs 30 °C, P=0.006) and cardiac output (vs 20 °C, P=0.001; vs 30 °C, P=0.001) at 40 °C were higher than those at 20 and 30 °C. Arterial O2 partial pressure, O2 saturation, and pH at 40 °C were lower than those at 20 and 30 °C. Arterial CO2 partial pressure at 40 °C was higher than that at 20 and 30 °C. No differences were observed in arterial-mixed venous O2 concentration difference (P=0.391) and plasma lactate concentration (P=0.134) at different ambient temperatures. These results indicate that exercise at 40 °C causes excessive high body temperature, decreased running economy, and increased cardiac output compared to exercise at 20 and 30 °C. We strongly suggest that trainers and veterinarians should anticipate the occurrence of increased thermal stresses when ambient temperature is extremely high even in dry conditions and prepare to mitigate the risk of EHI from the perspective of equine welfare.
| All Time | Past 365 days | Past 30 Days | |
|---|---|---|---|
| Abstract Views | 736 | 234 | 20 |
| Full Text Views | 66 | 26 | 0 |
| PDF Views & Downloads | 121 | 56 | 0 |
