Cardiac output and oxygen consumption in exercising Thoroughbred horses.
Abstract: This study characterizes the effects of exercise on the cardiac output (Q) and the metabolic rate (VO2) of trained Thoroughbred racehorses. Heart rate, Q, and arteriovenous (a-v)O2 difference were measured at rest and at three levels of submaximal treadmill exercise (1.6 m/s walk and 3-4 m/s trot at 6% incline, and 6.5 m/s horizontal canter). Heart rate and (a-v)O2 difference were also measured during maximal exercise (12.5 m/s gallop, 5% incline) to obtain an estimate of maximum O2 uptake (VO2max). The walk, trot, and canter represented 25, 45, and 55% VO2max. Mean heart rate went from 48.9 (rest) to 197 beats/min (gallop). Q ranged from 106 (rest) to 571 ml.min-1.kg-1 (canter), and stroke volume went from 1.34 (rest) to a maximum of 1.58 liters (walk). Thoroughbreds were able to bring hematocrit from 38 (rest) to 63% (gallop), and this adjustment allowed them to reach an impressive (a-v)O2 difference of 23 vol%, which represents a fivefold increase over resting values. These outstanding athletes probably support an aerobic scope of 40-fold.
Publication Date: 1987-12-01 PubMed ID: 3425767DOI: 10.1152/ajpregu.1987.253.6.R890Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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The research article explores how exercise impacts the cardiac output and metabolic rate in trained Thoroughbred racehorses. The study investigates the changes in heart rate, blood flow, and oxygen difference across several exercise levels and provides an estimate of maximum oxygen uptake.
Objective of the Research
- The primary objective of this study is to understand how exercise influences cardiac output (Q – the volume of blood the heart pumps per minute) and metabolic rate (VO2 – the volume of oxygen consumed per minute) in Thoroughbred racehorses.
Methodology
- The researchers measured heart rate, cardiac output, and the difference in oxygen concentration between the incoming (arterial) and outgoing (venous) blood in the studied horses. These measurements were conducted both when the horses were at rest and during three levels of submaximal treadmill exercise. This included a 1.6 m/s walk, a 3-4 m/s trot on a 6% incline, and a 6.5 m/s horizontal canter.
- Additionally, the horses’ heart rate and oxygen difference were measured during a maximum level of exercise, a 12.5 m/s gallop on a 5% incline, to estimate maximum oxygen uptake (VO2max).
- The researchers indicated that the walk, trot, and canter represented 25%, 45%, and 55% of the VO2max respectively.
Results
- The study revealed significant changes in heart rate, which increased from an average of 48.9 beats per minute at rest to 197 beats per minute during the highest level of exercise.
- The cardiac output ranged from 106 ml.min-1.kg-1 at rest to 571 ml.min-1.kg-1 during the canter, while the stroke volume increased from 1.34 liters at rest to a maximum of 1.58 liters during the walk.
- It was also observed that trained Thoroughbreds could raise their hematocrit (the volume of red blood cells in the blood) from 38% at rest to 63% during exercise. This ability enabled them to achieve an impressive oxygen difference of 23 volume percent, constituting a fivefold increase over resting values.
Conclusion
- Based on the findings of the research, the study concluded that Thoroughbred racehorses – characterised as excellent athletes – likely support an aerobic scope 40 times that of their resting values. This refers to their outstanding capacity to increase oxygen consumption during strenuous exercise.
Cite This Article
APA
Weber JM, Dobson GP, Parkhouse WS, Wheeldon D, Harman JC, Snow DH, Hochachka PW.
(1987).
Cardiac output and oxygen consumption in exercising Thoroughbred horses.
Am J Physiol, 253(6 Pt 2), R890-R895.
https://doi.org/10.1152/ajpregu.1987.253.6.R890 Publication
Researcher Affiliations
- Physiology Unit, Animal Health Trust, Newmarket, Suffolk, United Kingdom.
MeSH Terms
- Animals
- Basal Metabolism
- Cardiac Output
- Horses / physiology
- Oxygen Consumption
- Physical Exertion
- Reference Values
Citations
This article has been cited 5 times.- Tan Y, Martin TG, Harrison BC, Leinwand LA. Utility of the burmese Python as a model for studying plasticity of extreme physiological systems. J Muscle Res Cell Motil 2023 Jun;44(2):95-106.
- Mellor DJ, Beausoleil NJ. Equine Welfare during Exercise: An Evaluation of Breathing, Breathlessness and Bridles. Animals (Basel) 2017 May 26;7(6).
- Cheetham J, Regner A, Jarvis JC, Priest D, Sanders I, Soderholm LV, Mitchell LM, Ducharme NG. Functional electrical stimulation of intrinsic laryngeal muscles under varying loads in exercising horses. PLoS One 2011;6(8):e24258.
- Hampton M, Nelson BT, Andrews MT. Circulation and metabolic rates in a natural hibernator: an integrative physiological model. Am J Physiol Regul Integr Comp Physiol 2010 Dec;299(6):R1478-88.
- Painter PR. Allometric scaling of the maximum metabolic rate of mammals: oxygen transport from the lungs to the heart is a limiting step. Theor Biol Med Model 2005 Aug 11;2:31.
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