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European journal of applied physiology and occupational physiology1996; 74(1-2); 60-66; doi: 10.1007/BF00376495

Effects of exercise intensity and environmental stress on indices of oxidative stress and iron homeostasis during exercise in the horse.

Abstract: The effects of prolonged variable-intensity and short-term high-intensity exercise on indices of oxidative stress and iron homeostasis were compared in six fit horses under cool [20 degrees C, 40% relative humidity (RH)] or hot/humid (30 degrees C, 80% RH) environmental conditions. The exercise protocols were designed to simulate equine competition, including racing (intense exercise) or the speed and endurance phase of a 3-day event (prolonged exercise). Increased plasma concentrations of lipid hydroperoxides and haemolysate concentrations of oxidised glutathione (GSSG) were measured within 30 min of the completion of exercise, indicating production of reactive oxygen species (ROS) and lipid membrane peroxidation. The horses were unable to complete the prolonged exercise protocol at high temperature and humidity. This coincided with higher maximal values of lipid hydroperoxides [138.2 (17.7) microM and GSSG [110.6 (18.2) microM], compared to high-intensity [105.2 (14.9) microM and 63.6 (8.6) microM, respectively] or prolonged [100.7 (18.7) microM and 86.2 (9.1) microM, respectively] exercise performed under cooler environmental conditions. Significant correlations were found between the duration of the final stage of exercise during hot/humid environmental conditions and increased levels of lipid hydroperoxides (r = 0.85), GSSG (r = 0.94), xanthine (r = 0.92) and uric acid (r = 0.96). Exercise also decreased the iron (Fe)-binding antioxidant activity of the plasma and increased the total plasma Fe levels, although this was only significant for prolonged exercise in ambient conditions. There was no detectable free Fe in the plasma at any stage of exercise. Other changes in biochemical parameters had returned to pre-exercise levels within 24 h after exercise. The results show that exercise can induce changes in biochemical parameters that are indicative of oxidative stress in the fit horse and that this was, exacerbated during exercise at high temperature and humidity.
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Publication Date: 1996-01-01 PubMed ID: 8891501DOI: 10.1007/BF00376495Google Scholar: Lookup
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Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research article investigates the effects of different exercise intensities and environmental conditions on oxidative stress and iron levels in fit horses. The study compares the impact of prolonged variable-intensity exercise and short-term high-intensity exercise under cool and hot/humid conditions, with significant findings related to exercise-induced oxidative stress and iron homeostasis alterations in horses.

Study Information

  • The study was conducted on six fit horses and aimed to simulate the conditions that these horses could face during competition, such as intense exercise during a race or prolonged exercise over a three-day event.
  • The researchers used two types of environmental conditions, cool (20 degrees Celsius and 40% relative humidity) and hot/humid (30 degrees Celsius and 80% relative humidity), to assess the impacts of different exercise intensities.

Exercise Impact on Oxidative Stress in Horses

  • Following each exercise, increased plasma concentrations of lipid hydroperoxides and hemolysate concentrations of oxidized glutathione (GSSG) were observed within 30 minutes. These markers indicate the production of reactive oxygen species (ROS) and the occurrence of lipid membrane peroxidation, signs of oxidative stress.
  • The horses struggled to complete prolonged exercise in a hot and humid environment. In these conditions, higher maximum values of lipid hydroperoxides and GSSG were observed compared to measurements from high-intensity or prolonged exercise under cooler conditions.

Correlation Between Environmental Conditions and Oxidative Stress

  • Significant correlations were found between the duration of the final stage of exercise under hot/humid conditions and increased levels of lipid hydroperoxides and GSSG. This suggests that the intensity and duration of exercise in these extreme conditions could have caused an increase in oxidative stress.

Exercise Impact on Iron Levels in Horses

  • Exercise was shown to decrease the iron (Fe)-binding antioxidant activity of plasma and increase total plasma Fe levels. However, this was only significant for prolonged exercise in ambient conditions.
  • Crucially, there was no detectable free iron in the plasma at any stage of exercise, which means that the body’s iron homeostasis mechanisms continued to function effectively.

Return to Pre-Exercise Levels

  • Chemical parameters associated with oxidative stress generally returned to pre-exercise levels within 24 hours after exercise. So, while exercise caused short-term changes, these were not persistent.

Conclusions

  • The study concludes that exercise can cause temporary changes in biochemical parameters indicating levels of oxidative stress in fit horses. This effect is exacerbated when exercise occurs under high temperature and humidity conditions.

Cite This Article

APA
Mills PC, Smith NC, Casas I, Harris P, Harris RC, Marlin DJ. (1996). Effects of exercise intensity and environmental stress on indices of oxidative stress and iron homeostasis during exercise in the horse. Eur J Appl Physiol Occup Physiol, 74(1-2), 60-66. https://doi.org/10.1007/BF00376495

Publication

European journal of applied physiology and occupational physiology
ISSN: 0301-5548
NlmUniqueID: 0410266
Country: Germany
Language: English
Volume: 74
Issue: 1-2
Pages: 60-66

Researcher Affiliations

Mills, P C
  • Equine Centre, Animal Health Trust, Newmarket, UK.
Smith, N C
    Casas, I
      Harris, P
        Harris, R C
          Marlin, D J

            MeSH Terms

            • Animals
            • Female
            • Glutathione / metabolism
            • Homeostasis / physiology
            • Horses
            • Iron / blood
            • Lipid Peroxides / metabolism
            • Male
            • Oxidative Phosphorylation
            • Oxidative Stress / physiology
            • Oxygen Consumption / physiology
            • Physical Exertion / physiology
            • Purine Nucleotides / metabolism
            • Reactive Oxygen Species / metabolism

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