Journal of animal science2016; 94(10); 4067-4075; doi: 10.2527/jas.2015-9988

The effect of oxidative stress during exercise in the horse.

Abstract: Oxidative stress is an imbalance of the oxidant-to-antioxidant ratio in the body. Increases in oxidative stress and changes in antioxidant status have been shown during endurance and intense exercise and eventing competition in horses. Antioxidants include vitamins, minerals, enzymes, and proteins that must be synthesized in the body or obtained from the diet. Therefore, exercise level and diet are both factors that play a role in influencing the oxidative stress and antioxidant status of the equine athlete. Along with exercise intensity and duration, diet, age, and training program can also affect oxidative stress in the horse. Several studies using exogenous supplementation of vitamin E, vitamin C, and alpha-lipoic acid have shown positive results in decreasing the effects of exercise (endurance and intense exercise)-induced oxidative stress and increasing the antioxidant status based on the markers and antioxidants measured, whereas other studies using superoxide dismutase showed little effects on the exercise horse. The "free radical theory of aging" states that long-term effects of the degenerative changes associated with aging may induce oxidative stress. However, in old horses (22 ± 2 yr), lipid peroxidation levels and blood antioxidant concentrations were similar to those found in younger but mature (12 ± 2 yr) horses both at rest and during exercise. Other studies found that yearlings (18 ± 2.4 mo) that are novel to forced exercise had less lipid peroxidation and greater antioxidant status than mature mares (13 ± 2.1 yr) prior to exercise training. Exercise training reduced oxidative stress markers and improved antioxidant status in mares, whereas few effects were seen in yearlings. This indicates that youth provided more defense against oxidative stress due to exercise than the exercise training program. Other studies during competition (endurance, jumping, eventing, and racing) have investigated the influence on oxidative stress with varying results. Despite the multitude of studies examining the levels of lipid peroxidation, antioxidant status, and other related metabolites in the horse during exercise, we still have a long way to go before we fully understand the large variation in results both with and without antioxidant supplementation.
Publication Date: 2016-11-30 PubMed ID: 27898872DOI: 10.2527/jas.2015-9988Google Scholar: Lookup
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The research investigates the impact of oxidative stress on horses during exercise. It also explores the role of diet and exercise level in altering oxidative stress and antioxidant status in these equines during different types of exertion.

Understanding Oxidative Stress

  • Oxidative stress is a biochemical imbalance in the body caused by disproportion between oxidants and antioxidants. It’s often seen in endurance exercises or intense physical activities in horses.
  • Antioxidants include vital vitamins, minerals, enzymes, and proteins that can either be synthesized within the body or obtained from dietary sources. This establishes a link between oxidative stress, dietary habits, and exercise levels in equine athletes.

Factors Influencing Oxidative Stress

  • The study highlights that factors like the intensity and duration of exercise, diet, age, and the horse’s training program can substantially alter the levels of oxidative stress.
  • Supplementation of vitamins (like Vitamin E, Vitamin C) and alpha-lipoic acid have shown promising results in reducing exercise-induced oxidative stress, and boosting the overall antioxidant status of the horse.
  • However, other studies supplementing horses with the superoxide dismutase enzyme have seen minimal effects.

Free Radical Theory of Aging and Oxidative Stress

  • The ‘free radical theory of aging’ suggests accumulated degenerative changes can induce oxidative stress over time.
  • In older horses (22 ± 2 years), the study found lipid peroxidation levels and blood antioxidant concentrations to be similar to those in younger but mature horses (12 ± 2 years), even during exercises.
  • A different observation was made with yearlings (18 ± 2.4 months) new to forced exercise, showing lower lipid peroxidation and greater antioxidant status compared to mature mares (13 ± 2.1 years) prior to the exercise training.
  • The exercise training indeed reduced oxidative stress markers and improved antioxidant status in mares, but less impact was seen in yearlings.

Oxidative Stress during Competition

  • The research also indicates that different forms of competition like endurance, jumping, eventing, racing might cause varying impacts on oxidative stress levels in horses.
  • Despite numerous studies, the biological response and variation of oxidative stress in horses under different exercise conditions or with/without antioxidant supplementation remain vague and require more in-depth research for a comprehensive understanding.

Cite This Article

Williams CA. (2016). The effect of oxidative stress during exercise in the horse. J Anim Sci, 94(10), 4067-4075.


ISSN: 1525-3163
NlmUniqueID: 8003002
Country: United States
Language: English
Volume: 94
Issue: 10
Pages: 4067-4075

Researcher Affiliations

Williams, C A

    MeSH Terms

    • Aging
    • Animals
    • Antioxidants / administration & dosage
    • Ascorbic Acid / administration & dosage
    • Competitive Behavior
    • Diet
    • Dietary Supplements
    • Female
    • Horses / physiology
    • Lipid Peroxidation
    • Male
    • Oxidation-Reduction
    • Oxidative Stress / drug effects
    • Physical Conditioning, Animal
    • Reactive Oxygen Species / analysis
    • Reactive Oxygen Species / metabolism
    • Superoxide Dismutase / metabolism
    • Thioctic Acid / administration & dosage
    • Vitamin E / administration & dosage


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