What Does Lactic Acid Do into Animal Health and Performance ?
- Lactic acid is a crucial molecule involved in cellular respiration, glucose production, inflammation regulation, and molecular signaling.
- Under anaerobic conditions, glucose (via pyruvate) is converted into lactic acid to produce cellular energy.
- Energy production also occurs in the kidneys, where lactate is oxidized to generate ATP and CO2, a process that consumes oxygen.
- Lactic acid participates in gluconeogenesis in the liver and kidneys, converting lactate to glucose by consuming oxygen and ATP.
- Lactate exhibits anti-inflammatory properties, promotes immune tolerance, and plays roles in memory formation, neuroprotection, wound healing, ischemic tissue injury, and cancer progression.
Lactate is typically cleared by the liver, where it is reconverted into glucose via gluconeogenesis. Some lactate is also metabolized in the kidneys. The enzyme lactate dehydrogenase oxidizes lactate into pyruvate within mitochondria, generating NADH.
What Is Lactic Acidosis – Implications for Animal Health and Well-being ?
Lactic acidosis is characterized by elevated lactate levels and blood serum pH ≤ 7.35, often linked to metabolic acidosis in hospitalized individuals. It is classified into:
- Type-A: Caused by hypoperfusion and tissue hypoxia, common in shock (e.g., septic, cardiogenic) and anaerobic muscle activity.
- Type-B: Results from non-hypoxic causes such as liver disease, medications (e.g., metformin), excessive exercise, and malignancies.
Elevated lactic acid levels worsen underlying conditions, increasing mortality risks. Severe levels can reduce heart and vascular contractility, leading to profound hemodynamic consequences.
Causes of Lactic Acid Build-Up
Elevated lactate results from increased production, decreased clearance, or both. Causes include:
- Septic shock: Cardiovascular dysfunction and reduced peripheral tissue perfusion.
- Anaerobic muscle activity: Common in high-intensity exercise.
- Diabetic ketoacidosis: Metabolic stress and hypoperfusion.
- Thiamine deficiency: Shifts metabolism towards anaerobic pathways.
- Liver failure: Reduces lactate clearance.
Tying Up in Horses
What Makes Horses “Tie Up”?
- Performance horses often “tie up” due to lactic acid accumulation from anaerobic metabolism during high-intensity exercise.
- Excess lactate lowers muscle pH, reducing metabolic efficiency and causing fatigue. Prolonged muscle contraction results in muscle soreness or “tying up,” where large muscle groups seize up, sometimes immobilizing the horse.
Variability Among Horses
- Fit and well-trained horses tolerate higher lactate levels better than less-conditioned ones. Lactate tolerance depends on individual fitness and training levels.
Role of Calcium and Mitochondrial Exhaustion
- High intracellular calcium concentrations are linked to muscle contraction issues.
- Mitochondria recycle calcium during muscle activity. When mitochondria are exhausted, calcium builds up, preventing muscle relaxation.
- Excess lactate and acidity further impair mitochondrial function and energy production.
Hidden Dangers of Muscle Fatigue
Skeletal Impact
- Fatigued muscles lose control over tendons, increasing risks of skeletal injuries like bowed tendons and fractures.
Circulatory and Respiratory Impact
- Fatigue in arterioles (muscular blood vessels) may contribute to circulatory problems.
- Diaphragm fatigue reduces respiratory efficiency, limiting oxygen intake and carbon dioxide expulsion.
Solutions for Managing Lactic Acid and Muscle Fatigue
Training and Management
- Proper training increases aerobic capacity, reducing lactate buildup and enhancing lactate tolerance.
- Warm-ups, warm-downs, and adjusting feed on rest days help mitigate tying up.
Nutritional Support
- Vitamin E and Selenium: Protect muscle cell integrity and act as antioxidants. Supplementation can prevent deficiencies but offers limited additional protection.
- Pyruvate Conversion: Supplements aiding pyruvate conversion can reduce lactate buildup and improve energy production during anaerobic metabolism.
Conclusion
Improvements in biochemistry, nutrition, and training methods provide valuable tools for managing lactic acid and muscle fatigue in horses. By adopting a holistic approach to horse care, trainers can enhance performance, prevent tying up, and ensure overall muscle health.