What Limits Performance Under Stress?

By Dr Corinne Hills, DvmTargeted Supplementation For Heat, Travel, And Training

Modern racehorses are already fed balanced daily rations; so, energy, protein, and fat-soluble vitamins are not usually the limiting factors in performance. Under Gulf racing conditions, the real question becomes: What short-term physiological gaps are created by heat, travel, and intense training; and how can they be filled precisely and safely?

In hot environments, horses experience more than sodium loss alone. Stress can increase demand for:
• Magnesium, calcium, and potassium (neuromuscular balance)
• B-group vitamins (energy metabolism, appetite, and along with iron and copper, support of normal red cell synthesis)
• Phosphate and amino acids (energy demand, buffering, and muscle recovery)
• Vitamin C (oxidative stress support)
• Electrolytes include sodium, potassium, chloride, calcium, phosphorus, and magnesium (hydration, energy metabolism, nerve, and muscle function)

Changes in metabolism resulting from imbalances in these nutrients are often subtle. They may appear as slower recovery, reduced appetite, dullness, or inconsistent performance rather than overt clinical disease.

Two Supplementation Approaches

Sodium-Dominant Strategies focus primarily on replacing sodium chloride (table salt) to support hydration. While sodium replacement can be necessary, large sodium boluses require careful timing with water intake, as increased concentrations in the gut may act as an osmotic draw, temporarily altering systemic fluid distribution.

Sodium-dominant supplements do not address broader metabolic recovery, either. Endurance horses lose significant amounts of sodium during prolonged exercise; but even in those horses, replacement must be balanced with water intake and other electrolytes including potassium, calcium, magnesium, and phosphorus.

Racehorse training sessions are shorter in duration than endurance competition; so total sodium losses are typically less extreme. However, moderate sweat loss may have a proportionally greater impact on intracellular electrolytes such as potassium. In addition, urinary potassium excretion can further influence balance. For these reasons, careful attention to relative electrolyte balance, not sodium alone, is warranted in racehorses.

Balanced Systemic Support aims to support the entire metabolic system during stress. Pro-Dosa BOOST is an oral, multi-nutrient paste, manufactured under PIC/S GMP pharmaceutical standards. It provides:
• Balanced electrolytes (Na, K, Mg, Ca, P)
• High-dose B-complex vitamins
• Vitamin C
• Trace minerals
• Free amino acids

Sodium is included within a complete, balanced multi-nutrient matrix. If and when additional sodium is required, measured salt can be added in controlled amounts, allowing precise adjustment to the individual horse, environment, and workload once water intake is confirmed. Practical experience from hot-climate racing jurisdictions (Hong Kong, China, and Singapore) supports this controlled approach. Racehorses commonly receive a syringe of Pro-Dosa, alone, after gallops and pre-race. Even under high heat and humidity, additional sodium chloride is not always required, and when indicated, is introduced conservatively.

No supplement replaces correct management and veterinary oversight. However, in environments where margins are measured in lengths or fractions of a second, a complete, balanced, physiological strategy can support resilience and recovery across a demanding campaign.

Racehorses
• Primary needs: neural and muscular function, energy metabolism, support of normal red cell function, appetite, recovery, travel resilience
• Best strategy: Pro-Dosa alone, with small salt additions (5-10g, only if required on very hot days, and with confirmed water intake)

Sport horses (SJ / Eventing / Dressage)
• Primary needs: muscle cell relaxation, neural function, appetite, recovery, travel resilience
• Best strategy: Pro-Dosa alone, with small salt additions (5-10g, only if required, and with confirmed water intake)

Endurance horses
• Sodium losses can be high, but failure is rarely sodium alone. Performance limitation is often multifactorial, involving neuromuscular factors (Mg, Ca, P), intracellular electrolyte imbalance (K), metabolic fatigue (B group vits, P), muscle fibre relaxation (Ca, Mg), and appetite regulation under oxidative and hormonal stress (B group vitamins and vitamin C).
• Best strategy: Pro-Dosa as the base, with 0, 5, 10, or 15g salt added, in response to the individual, loop by loop. Delay until drinking is confirmed.