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Endocrine response to exercise in young and old horses
1Department of Animal Science, Cook College, Rutgers-State University of New Jersey, New Brunswick 08901, USA.
Equine Veterinary Journal. Supplement
|February 5, 2000
Summary
Older horses exhibit an altered endocrine response to exercise compared to younger horses, with significant differences observed in plasma renin activity and hormone concentrations at maximal oxygen uptake. This suggests age impacts physiological adaptations to physical exertion in equine athletes.
Area of Science:
- Equine physiology
- Endocrinology
- Exercise science
Background:
- Age-related physiological changes can influence an animal's response to exercise.
- Understanding the endocrine system's role in exercise is crucial for equine health and performance.
Purpose of the Study:
- To investigate whether age alters the endocrine response to a standardized incremental exercise test in horses.
- To compare plasma concentrations of key hormones and renin activity between young and old mares during exercise.
Main Methods:
- Six young and six old Standardbred and Thoroughbred mares were subjected to a graded exercise test (GXT).
- Blood samples were collected at rest and during exercise to measure plasma renin activity (PRA), atrial natriuretic peptide (ANP), arginine vasopressin (AVP), aldosterone (ALDO), and endothelin-1 (ET-1).
- Hormone concentrations were analyzed using radioimmunoassay kits.
Main Results:
- Resting hormone levels did not differ significantly between young and old mares.
- Exercise increased PRA, ANP, AVP, and ALDO in both age groups, while ET-1 remained unchanged.
- At maximal oxygen uptake (VO2max), older mares showed significantly different PRA, ANP, AVP, and ALDO levels compared to younger mares.
Conclusions:
- Older horses demonstrate an age-altered endocrine response to exercise, particularly at high intensities.
- These findings suggest that physiological adaptations to exercise may be modulated by aging in horses.