Consider Preloading Electrolytes to Exercising Horses

Exercising horses lose valuable electrolytes in sweat and can easily become dehydrated. Owners often offer electrolytes following work or competition to replace these losses; however, pre-exercise electrolytes may be an alternate approach. Providing electrolytes prior to prolonged moderate-intensity work appears to fully replenish those lost in sweat and minimize other exercise-related changes in the body’s acid-base balance.^*

Moderate- to high-intensity exercise can induce substantial acid-base disturbances, which affect energy generation in the muscle cells and fatigue. Such disturbances lead to dehydration and an altered pH of the blood, typically to a more basic pH, a condition called alkalosis. In rare and severe cases, kidney failure may occur.

To determine if preloading electrolytes is an effective means of maintaining the body’s hydration and electrolyte balance during prolonged moderate intensity exercise, veterinary researchers conducted a series of studies. They administered 3 or 8 liters (L) of an electrolyte solution to measure specific acid-base variables before, during, and after exercise. These acid-base variables were compared to those measured in horses offered only water.

Researchers measured these acid-base variables: hydrogen ions, total carbon dioxide levels (as a measure of how well the body is balancing electrolytes), and total body alkalosis (basic pH) versus acidosis (acidic pH).

“Increases in hydrogen ions inhibit ATP (energy) production and affect muscle contraction. In addition, the body’s pH needs to be maintained in a very narrow range. When the body goes too far in either direction from neutral pH, it can negatively affect the horse’s performance,” explained Kathleen Crandell, Ph.D., a nutritionist with Kentucky Equine Research.

Horses supplemented with 3 L electrolyte/water had minimal changes in acid-base variables.

Those receiving 8 L of an electrolyte solution one hour prior to exercise, a level intended to replenish sweat losses incurred at that activity level, showed beneficial effects. Hydrogen ion levels were maintained, carbon dioxide levels were decreased, and alkalosis typical of endurance exercise was minimized.

According to the researchers, preloading horses with 8 L of an electrolyte solution replaces requisite electrolytes and mitigates dehydration-induced alkalosis. Thus, preloading can help counter “the substantial fluid and ion losses” that occur during exercise.

Kentucky Equine Research offers research-proven electrolyte supplements, including Restore SR (or Restore in some parts of the world). This concentrated electrolyte powder contains the latest technology in electrolyte supplements for horses, including a proprietary slow-release mechanism that allows sodium to be released gradually into the gastrointestinal tract for sustained absorption.

^*Waller, A.P., and M.I. Lindinger. 2022. Tracing acid-base variables in exercising horses: Effects of pre-loading oral electrolytes. Animals (Basel) 13(1):73.