Effects of draught load exercise and training on calcium homeostasis in horses.

This study investigated how performing draught load exercises, which are a specific type of physical exertion, affects calcium regulation in young horses. The research found that while this type of exercise does have an impact on calcium regulation and associated biological responses, these effects do not change over time with increased training.

Research Methodology

• The research team selected five 2-year-old untrained Standardbred horses for the study.
• All the workout exercises were performed on a treadmill, inclined at a 6% angle, with an attached draught load of 40 kg.
• The four-month-long training programme commenced with a Standardized Exercise Test (SET 1), composed of six 5-minute increments, starting at a speed of 1.38 m/s, each increment increasing the speed by 0.56 m/s.
• Subsequent training constituted low-speed exercise sessions (LSE), with a constant speed of 1.67 m/s for 60 minutes; there were a total of 48 such sessions.
• A similar SET was performed again after the 16th and 48th LSE training session (SET 2 and SET 3 respectively) with the identical testing protocol as SET 1.
• Blood samples were collected from these horses at various stages: prior, during, and post-SET performances and before and after the 1st, 16th, 32nd, and 48th LSE training sessions. These samples were tested for levels of lactate, total plasma calcium, ionized blood calcium (Ca(2+)), blood pH, plasma inorganic phosphorus (P(i)), and parathyroid hormone (PTH).

Research Outcomes

• The tests performed during the SETs revealed a decrease in ionized calcium (Ca(2+)) and an increase in lactate, P(i), and PTH levels in the horses’ blood samples.
• The LSE tests showed an increase in both the pH and P(i) levels, whilst levels of lactate, ionized Ca(2+), total calcium, and PTH remained unchanged.
• Throughout the entire training programme duration, the researchers did not observe any significant changes in the calcium metabolism of the horses.

Implications of the Study

• The research implies that the form of physical exercise affects calcium homeostasis and PTH responses in horses. However, the study also found that these effects remained constant despite ongoing training, suggesting that the horses’ physiological systems adapt to resist changes in calcium metabolism even as they undergo exercise-induced stress.

This study contributes valuable knowledge to the understanding of equine physiology under training conditions, which is potentially useful for optimizing training programmes and maintaining the health and performance of horses.