Equine plasma beta-endorphin concentrations are affected by exercise intensity and time of day.
Abstract: Eight mature mares were exercised for 20 min at 60% VO2max and to fatigue at 95% VO2max. Plasma beta-endorphin (EN) concentrations were determined before exercise, after a 10 min warm-up, and at the end of each exercise test. Mean +/- s.e. beta-endorphin concentrations were significantly (P < 0.05) higher following work at 95% VO2max when compared to that at 60% VO2max (420.0 +/- 102.7 vs. 269.9 +/- 30.69 pg/ml). Pre-exercise samples were collected between 1000 and 1500 h. In order to evaluate whether any cyclic changes in EN secretion effects may have influenced results, a subsequent study was completed using 12 horses to assess diurnal fluctuations in EN concentrations, by measuring EN concentration every 2 h for a 24 h period. There was no statistical difference in mean values at any time between 0800 and 2000 h. Whether individual differences in EN concentrations reflected varying degrees of stress associated with the exercise could not be determined. Any possible link between EN concentration and exercise stress in exercising horses awaits clarification.
Publication Date: 2000-02-05 PubMed ID: 10659319DOI: 10.1111/j.2042-3306.1999.tb05285.xGoogle Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research investigates how plasma beta-endorphin levels in horses are influenced by the intensity of physical exertion and timing throughout the day. It concludes that tougher exercise produces higher endorphin levels, while the time of day seems to have little effect.
Methodology and Participants
- The research was conducted on eight mature female horses or mares, with the exercise intensity and time of day being the two primary variables under investigation.
- Each mare was subjected to 20 minutes of exercise at 60% of their maximum oxygen consumption (VO2max), and intense exercise at 95% VO2max until fatigue.
- To measure the impact of these conditions on beta-endorphin (a type of hormone) concentrations, samples were taken before the workout, after a 10-minute warm-up, and at the end of each test.
Primary Observations
- The researchers observed significant increments in the beta-endorphin concentrations after the horses exercised at 95% of their VO2max as compared to 60%. These findings suggest beta-endorphin levels in horses are influenced by exercise intensity.
- Pre-exercise samples were collected throughout the day, between 10 AM and 3 PM, to investigate the influence of the time of day.
Follow-up Study
- To further assess the potential cyclical fluctuations in endorphin secretion, a subsequent study was completed, involving 12 horses. Beta-endorphin concentrations were measured every two hours over a 24-hour period.
- Despite the variety of testing times throughout the day, the results showed no significant differences in mean concentrations at any point between 8 AM and 8 PM, suggesting the time of day does not significantly influence beta-endorphin concentration.
Conclusions and Further Research
- The researchers could not determine if there were individual differences in endorphin concentrations due to variances in stress levels caused by the exercise.
- Any potential correlation between beta-endorphin concentration and exercise-induced stress in horses remains to be clarified, indicating the need for additional research to make conclusive determinations.
Cite This Article
APA
Mehl ML, Sarkar DK, Schott HC, Brown JA, Sampson SN, Bayly WM.
(2000).
Equine plasma beta-endorphin concentrations are affected by exercise intensity and time of day.
Equine Vet J Suppl(30), 567-569.
https://doi.org/10.1111/j.2042-3306.1999.tb05285.x Publication
Researcher Affiliations
- Department of Veterinary Clinical Sciences, Washington State University, Pullman 99164, USA.
MeSH Terms
- Animals
- Circadian Rhythm
- Female
- Horses / blood
- Muscle Fatigue
- Oxygen Consumption
- Physical Conditioning, Animal
- beta-Endorphin / blood
Citations
This article has been cited 2 times.- Cravana C, Medica P, Ragonese G, Fazio E. Influence of training and competitive sessions on peripheral β-endorphin levels in training show jumping horses. Vet World 2017 Jan;10(1):67-73.
- Fazio E, Medica P, Aronica V, Grasso L, Ferlazzo A. Circulating beta-endorphin, adrenocorticotrophic hormone and cortisol levels of stallions before and after short road transport: stress effect of different distances. Acta Vet Scand 2008 Mar 3;50(1):6.
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