Effects of high-intensity exercise on plasma catecholamines in the thoroughbred horse.
Abstract: In Study 1, a single speed test of 6 to 12 m/sec was performed for 2 mins at an incline of 5 degrees on a high-speed treadmill (single-step test). Only one speed was performed per session and blood samples were taken before and after the test. In Study 2 horses cantered for 1 min at increasing speeds of 6 to 13 m/sec on an incline of 3 degrees (multiple-step test). Blood samples were taken before exercise, throughout the test and during recovery. In the single-step test plasma concentrations of adrenaline and noradrenaline both increased at speeds of 9 m/sec, as did blood lactate. Mean concentrations of adrenaline and noradrenaline at the end of the 12 m/sec test were 153 and 148 nmol/litre, respectively. Plasma concentrations were similar over all speeds although there was a tendency for the increase in noradrenaline to be greater than that of adrenaline at the lower speeds. The multiple-step test resulted in smaller increases in both adrenaline and noradrenaline. Although again closely correlated, increases in adrenaline were 20-30% greater than those for noradrenaline. In both exercise models, changes in plasma adrenaline and noradrenaline values with exercise showed an exponential relationship to plasma lactate. A plasma half-life of less than 30 secs was indicated during recovery from the multiple-step test. Changes in adrenaline and noradrenaline were much greater than previously recorded in man and emphasise the importance of catecholamines in mediating the physiological response of the horse to exercise.
Publication Date: 1992-11-01 PubMed ID: 1459060DOI: 10.1111/j.2042-3306.1992.tb02877.xGoogle Scholar: Lookup
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- Journal Article
Summary
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This research investigates how high-intensity exercise impacts the levels of certain hormones in horses. The study found that more vigorous exercise led to increases in adrenaline and noradrenaline, hormones that help the body respond to stress, along with a related increase in blood lactate, a marker of strenuous exercise.
Research Methodology
- The researchers carried out two types of tests. In the first (single-step test), the horses ran at a single speed of between 6 and 12 meters per second for 2 minutes, on a treadmill with a 5-degree incline. Blood samples were taken before and after the test.
- In the second test (multiple-step test), horses ran for 1 minute at increasing speeds of 6 to 13 meters per second, with a 3-degree incline. Here, blood samples were taken before the exercise, during the test, and during recovery.
Results of the Single-Step Test
- In the single-step test, plasma concentrations of adrenaline and noradrenaline increased at speeds of 9 meters per second. Blood lactate levels also rose.
- In the test that reached speeds of 12 meters per second, adrenaline and noradrenaline concentrations were both around 150 nmol/litre.
- Plasma concentrations were roughly the same at all speeds, although noradrenaline tended to increase more than adrenaline at lower speeds.
Results of the Multiple-Step Test
- The multiple-step test caused smaller increases in both adrenaline and noradrenaline.
- Despite being closely correlated, the increases in adrenaline were 20-30% greater than those for noradrenaline.
- During recovery from the multiple-step test, a plasma half-life of less than 30 seconds was indicated.
Insights and implications
- Both exercise models showed that changes in plasma adrenaline and noradrenaline levels during exercise were exponentially related to plasma lactate levels, indicating that more strenuous exercise led to higher levels of these stress hormones.
- The changes in adrenaline and noradrenaline levels were greater than previously observed in humans, highlighting the important role of these hormones in horses’ physiological response to exercise.
Cite This Article
APA
Snow DH, Harris RC, MacDonald IA, Forster CD, Marlin DJ.
(1992).
Effects of high-intensity exercise on plasma catecholamines in the thoroughbred horse.
Equine Vet J, 24(6), 462-467.
https://doi.org/10.1111/j.2042-3306.1992.tb02877.x Publication
Researcher Affiliations
- Department of Physiology, Animal Health Trust, Newmarket, Suffolk, UK.
MeSH Terms
- Animals
- Breeding
- Epinephrine / blood
- Exercise Test / veterinary
- Half-Life
- Heart Rate
- Horses / physiology
- Lactates / blood
- Norepinephrine / blood
- Physical Exertion / physiology
Citations
This article has been cited 7 times.- Henshall C, Randle H, Francis N, Freire R. Habit Formation and the Effect of Repeated Stress Exposures on Cognitive Flexibility Learning in Horses. Animals (Basel) 2022 Oct 18;12(20).
- Henshall C, Randle H, Francis N, Freire R. The effect of stress and exercise on the learning performance of horses. Sci Rep 2022 Feb 4;12(1):1918.
- Frick L, Schwarzwald CC, Mitchell KJ. The use of heart rate variability analysis to detect arrhythmias in horses undergoing a standard treadmill exercise test. J Vet Intern Med 2019 Jan;33(1):212-224.
- Terada M, Momozawa Y, Komano M, Kusunose R, Sato F, Saito TR. Changes in the heart rate and plasma epinephrine and norepinephrine concentrations of the stallion during copulation. Reprod Med Biol 2005 Jun;4(2):143-147.
- Jimenez M, Hinchcliff KW, Farris JW. Catecholamine and cortisol responses of horses to incremental exertion. Vet Res Commun 1998 Feb;22(2):107-18.
- Tadich T, Calderón-Amor J, González I, Palma B, Lagos J. Working like a mule? The physiological toll of heavy loads on mules. Front Vet Sci 2025;12:1725279.
- Potier JF, Louzier V. Evaluation of stress markers in horses during hippotherapy sessions in comparison to being ridden by beginners. Anim Welf 2023;32:e10.
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