Potassium vs. Sodium

Not entirely sure how to answer this.  You need to replete both during and after strenuous exercise.  Severe alterations in both are potentially deadly.  As for how quickly you lose each relative to one another, I really don't know.  If you're taking in both, you'll probably be ok, but I wouldn't skimp on either.  You really don't have "stores" of either one in your body.  You have sodium and potassium both in your cells and in the bloodstream already, and they're in an equilibrium as established by cellular pumps.  Once you lose it in the blood, it'll come out of the cells to replace that.  Lower intracellular potassium and sodium are the real problem.

Not sure if that really helps or not.

Blood pressure as a function of sodium levels is only related to total body fluid volume.  It's not really of much concern in the acute setting where you're having large fluid shifts like during intense exercise.  You do have to replete sodium but not for blood pressure.

And normally functioning kidneys regulate potassium levels very well.  You can take in huge doses and get away with it because of that.  Potassium pills do exist, and we use them for our patients with potassium issues all the time.  The only people you have to worry about getting hyperkalemic are those with underlying kidney problems who can't eliminate the excess.  People with normal kidneys don't have that problem.

Kidney excretion is a rapid and efficient process.  I'm not sure where you're getting your info from, but I deal with this and actual patients on a daily basis.  You simply cannot overload somebody with normal renal function with oral potassium.  No offense, but you didn't even know that oral potassium supplements exist, so I doubt you have any experience with them.

And I never said that blood pressure wasn't important.  I'm saying that the sodium is not the primary osmotic force determining your blood pressure, and hyponatremia doesn't cause hypotension during exercise.  Hypovolemia is what does that, and that isn't a function of your sodium.

I'm honestly not sure which is more important to replace first, as sodium levels probably change more, but potassium levels that are out of whack are potentially more dangerous in the short term.  Just take in something with both.

I always hate threads like this because I come off sounding like a bad guy.

I wouldn't want to have to mess with individual eletrolytes or even marconutrients for that matter during a race or training. I'm a Hammer Nutrition fan, so I use their stuff (HEED, Perpeteum, Endurolytes, gels) in quantities they recommend based on activity (intensity and duration) and climate. It seems to be working well for me.  I experimented a little to figure out precisely what works, and I build it into my plan so I don't have to think about it when I'm training.

And that's basically the solution to the debate.  Just take in something that's all inclusive and don't worry about picking and choosing.

Does beer count?

Thanks for all the interesting reading guys.  I hope no one is upset about the disagreements contained in this thread because it actually led to more discussion which means you have increased the educational value for all of us non-experts.  Consider it a healthy debate with nothing but positive results.  At least from me. 

To give you some context, in the other thread I referenced someone commented on what seemed to them like a relatively high potassium level in relation to sodium in the new Jelly Belly Sport Beans.  After reading your discussion, that concern seems completely unnecessary.  I tried some of them this weekend on my long run.  I love the taste, but I ate them all in the first three miles because if I had to listen to that damn rattling coming from my pocket for another minute I was going to kill someone, and I was alone.  I'm sticking to my gels.  (get it?  sticky?  gels?  I think it was funnier in my head.)

Booooo.