Why do marathon runners need to replenish their potassium after a race?
Thursday, December 24th, 2009 at
2:35 AM
I’m having a hard time understanding why, its a practice question for a physiology test how would the kidney tie into the relationship of marathon runner and potassium stores?
Filed under: Potassium Questions
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During a marathon, excessive sweating often occurs, resulting in the loss of water, a loss of blood volume, and, thus, a lower blood pressure. To retain water, kidneys often release renin (via juxtaglomerular cells), which acts to increase the secretion of aldosterone. Aldosterone functions by increasing the production of channels and transporters that help in the retention of sodium, including Na+/K+ ATPase (the retention of Na+ is coupled with the retention of water via osmosis). These ATPases, which promoting the retention of Na+ aid in the loss of K+ (as Na+ moves inward into the blood, K+ moves out in the tubule lumens of the nephrons and is lost). Thus, aldosterone promotes Na+/water retention as well as K+ loss. As a result, it may be necessary to restore potassium stores.