Effect of physical activity on human potassium metabolism in a hot and humid environment

Previous investigations have suggested that there are high potassium losses during heavy physical activities in hot climates. In order to determine if high levels of potassium losses could be offset by potassium loading, this study was conducted with five long-distance track runners who had trained in hot and humid environments. The liquid supplements containing 4.3, 98.0, and 0.0 mEq/liter of potassium were given 1 to 2 hr before physical activity. The daily diet contained 2.6 g of potassium. A sodium and potassium balance study was conducted in which stool, urine, and dermal losses were measured. In order to determine if there was a change in the distribution of body potassium during physical exercise, seven subjects total body potassium was estimated before and after exercise. This measurement was performed by counting 40K in a whole body counter. Although the subjects with potassium supplementation and higher urinary sodium and potassium losses, the 98 mEq/liter of potassium supplement resulted in a positive potassium balance. The subjects' potassium requirements exceeded the National Research Council suggested dietary intake. The total body potassium measurements indicated that the counting efficiency of 40K increases significantly immediately after the period of vigorous exercise.