Respiratory and metabolic responses in the horse during moderate and heavy exercise.
Abstract: Thoroughbred horses were exercised to fatigue on a treadmill at 62% and 100% of their VO2max. Hypoxemia occurred at the onset of exercise under both exercise conditions. This hypoxemia persisted to fatigue during the heavy exercise but progressively diminished as the exercise continued and had disappeared by the end of exercise at the lighter load. As a result of the hypoxemia the oxygen content of arterial blood during exercise at VO2max was 17% below its carrying capacity. However, under both experimental conditions the CaO2 still exceeded that of rest owing to an elevation in hemoglobin concentration. The temperature of blood at the point of fatigue was similar, 41.0 +/- 0.2 degrees C and 41.1 +/- 0.2 degrees C, for exercise at 62% and 100% VO2max, respectively. Muscle samples collected at rest and at the termination of exercise did not demonstrate major differences between the exercise conditions except for a higher [lactate] and lower pH following the heavy exercise. From these results it can be suggested that the combined effects of an elevated body temperature, changes in muscle pH, and oxygen delivery may all be factors contributing to limit exercise capacity in the horse.
Publication Date: 1990-09-01 PubMed ID: 2293204DOI: 10.1007/BF00370771Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The study investigates how exercises of different intensities affect the respiratory and metabolic responses in horses, with particular focus on the oxygen carrying capacity of arterial blood, body temperature, muscle pH and lactate levels, all factors that may influence a horse’s performance during exercise.
Research Methodology and Conditions
- The study involved Thoroughbred horses that were made to exercise on a treadmill until they reached their point of fatigue.
- Two different intensity levels were utilized for the exercise conditions, one at 62% and the other at 100% of the horse’s maximal oxygen consumption (VO2max) level.
- Monitoring of the oxygen level in the arterial blood, blood temperature, and changes in muscle pH and lactate levels were carried out both at rest and at the termination of exercise.
Result Overview
- Hypoxemia, which is low oxygen content in the blood, was observed to occur at the onset of both moderate and intense levels of exercise.
- However, the hypoxemia condition gradually diminished as exercise continued at a moderate (62% VO2max) level and completely vanished by the end of the exercise. On the other hand, at a higher intensity (100% VO2max), hypoxemia persisted all through the exercise session.
- As a result of this hypoxemia, the oxygen content in the arterial blood during heavy exercise was found to be 17% below its carrying capacity.
- Despite the decrease in oxygen content, the Oxygen Carrying Capacity (CaO2) of the blood still remained higher than the resting levels owing to an elevation in hemoglobin concentration.
- The blood temperature remained fairly consistent at both levels of exercise with a mean temperature around 41 degrees Celsius.
- There were not significant differences in muscle samples taken at rest and at the end of exercise under the two exercise conditions, except for increased lactate concentration and decreased pH following heavy exercise.
Conclusion of the Research
- The findings suggest that the decrease in oxygen carrying capacity of the blood due to hypoxemia, the consistency in body temperature, and changes in muscle pH and lactate levels could all be factors contributing to the limit a horse’s exercise capacity.
- These factors combined, especially the persistence of hypoxemia during heavy exercise, could potentially impact the performance of the horse in intense physical activities.
Cite This Article
APA
Hodgson DR, Rose RJ, Kelso TB, McCutcheon LJ, Bayly WM, Gollnick PD.
(1990).
Respiratory and metabolic responses in the horse during moderate and heavy exercise.
Pflugers Arch, 417(1), 73-78.
https://doi.org/10.1007/BF00370771 Publication
Researcher Affiliations
- College of Veterinary Medicine, Washington State University, Pullman 99164-6610.
MeSH Terms
- Adenosine Triphosphate / metabolism
- Animals
- Blood Gas Analysis
- Body Temperature / physiology
- Glycogen / metabolism
- Horses / metabolism
- Horses / physiology
- Hydrogen-Ion Concentration
- Hypoxia / metabolism
- Hypoxia / physiopathology
- Lactates / metabolism
- Muscles / metabolism
- Oxygen / metabolism
- Oxygen Consumption / physiology
- Phosphocreatine / metabolism
- Physical Conditioning, Animal
- Pulmonary Gas Exchange / physiology
- Respiration / physiology
References
This article includes 14 references
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Citations
This article has been cited 7 times.- 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).
- Bukhari SSUH, McElligott AG, Parkes RSV. Quantifying the Impact of Mounted Load Carrying on Equids: A Review. Animals (Basel) 2021 May 7;11(5).
- Chaisson EJ. The natural science underlying big history. ScientificWorldJournal 2014;2014:384912.
- Romero-Suarez S, Mo C, Touchberry C, Lara N, Baker K, Craig R, Brotto L, Andresen J, Wacker M, Kaja S, Abreu E, Dillmann W, Mestril R, Brotto M, Nosek T. Hyperthermia: from diagnostic and treatments to new discoveries. Recent Pat Biotechnol 2012 Dec;6(3):172-83.
- Hackett RP, Ducharme NG, Gleed RD, Mitchell L, Soderholm LV, Erickson BK, Erb HN. Do Thoroughbred and Standardbred horses have similar increases in pulmonary vascular pressures during exertion?. Can J Vet Res 2003 Oct;67(4):291-6.
- Veeneklaas RJ, Verkleij CB, van Schie B, Harun MA, Everts ME. Preliminary studies on the concentration of Na+,K(+)-ATPase in skeletal muscle of draught cattle in Mozambique: effect of sex, age and training. Trop Anim Health Prod 2002 Sep;34(5):431-47.
- Bukhari SSUH, Parkes RSV. Assessing the impact of draught load pulling on welfare in equids. Front Vet Sci 2023;10:1214015.
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