Does usefulness of potassium supplementation depend on speed?

The research investigates the effects of potassium-rich and potassium-free electrolyte supplements on an endurance exercise test involving 13 trained Arabian horses. The results indicate that potassium supplementation may elevate plasma potassium levels during exercise, leading to a heightened risk of neuromuscular hyperexcitability.

Background and Objective

• The primary context of the study is the common practice of supplementing with potassium-rich electrolyte solutions during endurance events to counter sweat losses. There is uncertainty about whether this might increase the blood potassium concentration ([K+]), which can give rise to neuromuscular hyperexcitability and other adverse clinical outcomes.
• To gain more insights and to determine an answer to this problem, the researchers designed a study aiming to compare the impacts of a potassium-rich electrolyte supplement (EM+K) and a potassium-free supplement (EM-K) on plasma potassium levels, calcium levels ([Ca++]), and acid-base balance during an endurance incremental exercise test.

Methods

• The exercise test was undertaken on 13 endurance trained Arabian horses and involved three stages with increasing speed (6, 7, then 8 m/sec) each of 12km distance.
• The horses were split into two groups, one receiving the potassium-rich supplement and the other getting the potassium-free supplement. The supplements were given orally 60 minutes before the exercise and at each rest stop.
• A variety of blood parameters were analyzed at various points including pre-exercise, during exercise, each rest stop, and after 120 minutes of recovery.

Results

• The findings showed that with the increased speed of the last test, the horses supplemented with the potassium-rich electrolyte showed increased plasma potassium levels and decreased calcium levels compared to the potassium-free supplement group.
• The potassium-rich supplemented group also exhibited increased packed cell volume (PCV), glucose, and lactate levels during the high-speed stage.

Conclusions

• The study shows that the use of a potassium-rich supplement during endurance exercise can lead to higher potassium levels and thus a potential risk of neuromuscular hyperexcitability.
• It was speculated that the potassium-rich electrolyte supplement may have stimulated the release of epinephrine, leading to higher PCV and increased lactate production.
• The study ends with a practical implication suggesting that using a potassium-free supplement (which resulted in lower plasma potassium levels and higher calcium levels) might be safer, reducing the risk of disorders linked to neuromuscular hyperexcitability particularly during high-speed endurance races.