Does usefulness of potassium supplementation depend on speed?

Area of Science:

• Equine Exercise Physiology
• Sports Medicine
• Animal Nutrition

Background:

• Electrolyte supplements commonly contain potassium to offset sweat losses.
• Elevated plasma potassium during exercise, exacerbated by supplementation, may increase risks of neuromuscular hyperexcitability.
• The impact of potassium-rich electrolytes on equine physiology during strenuous exercise warrants investigation.

Purpose of the Study:

• To compare the effects of potassium-rich (EM+K) versus potassium-free (EM-K) electrolyte supplements on plasma potassium, calcium, and acid-base status in horses during incremental exercise.
• To assess the safety and efficacy of different electrolyte formulations in endurance-trained horses.

Main Methods:

• Thirteen endurance-trained Arabian horses underwent an incremental treadmill exercise test with three 12 km bouts at increasing speeds (6, 7, 8 m/sec).
• Horses received either EM+K or EM-K supplements orally before and during exercise.
• Blood samples were analyzed for electrolytes, acid-base status, packed cell volume, glucose, and lactate at various time points.

Main Results:

• Horses receiving EM+K exhibited higher plasma potassium concentrations at 8 m/sec compared to EM-K.
• Plasma calcium was lower, while packed cell volume, glucose, and lactate were higher in the EM+K group during the highest speed bout.
• Acid-base status showed transient changes, with plasma [H+] increasing at 8 m/sec.

Conclusions:

• Potassium-rich electrolyte supplementation (EM+K) elevates plasma potassium during intense exercise, potentially increasing the risk of neuromuscular hyperexcitability.
• Potassium-free supplements (EM-K) resulted in lower plasma potassium and higher plasma calcium, potentially mitigating risks.
• EM-K supplementation may be a safer strategy for managing electrolyte balance and reducing exercise-associated risks in endurance horses.