Effects of potassium intake on potassium, sodium and fluid balance in exercising horses.

This research article examines the effects of increased potassium intake on potassium, sodium, and fluid balances in horses, both in a rested state and after exercise. The key findings reveal that animals quickly adapt to a higher potassium diet primarily via increased urinary excretion and that the response post-exercise remains largely unaffected except for an increased sodium concentration in sweat.

Research Design

• The study was conducted using four Standardbred horses, which had two levels of potassium intake for 17 days in a crossover design. This setup allows researchers to examine effectively the effects of varying potassium intake on the same subject.
• These potassium levels were 4.1 and 5.4 mmol/kg of body weight per day. Measuring intake relative to body weight creates a uniform standard across individual animals.
• The researchers studied the effects of potassium, sodium, and fluid balance in two scenarios: at rest and in response to 29 km exercise. This helped determine the effects both in a steady state and post-exercise, respectively.

Findings: Adaptation to Increased Potassium Intake

• After new diets were introduced, potassium, sodium, and fluid intakes and outputs balanced within 24 hours.
• Bodies adapted primarily by increasing urinary potassium excretion, followed later by increased faecal excretion.
• The boosted urinary potassium excretion was coupled with a larger volume of urine (1.2-1.4 kg/day) and compensated by an increase in water intake.

Findings: Effects on Exercise

• The highest potassium intake resulted in an increased sodium concentration in sweat – from 123 +/- 5 mmol/l to 138 +/- 3 mmol/l.
• Post-exercise urinary sodium excretion was lower on the higher potassium diet.
• No differences were found in the extent of post-exercise hypokalaemia (low blood potassium) between the two diet levels. Even with higher potassium diet, horses still had reduced plasma potassium concentration 24 hours post-exercise.

Summary

• This study shows that horses swiftly adapt to an increased potassium intake chiefly by increasing urinary excretion.
• Exercise responses were mostly unaffected by the increased potassium intake, with the only notable difference being the increase in sodium concentration in sweat.