The secret word for today is "osmolarity". Now, we all know what to do when someone says the secret word? That's right... SCREAM REAL LOUD!!!
First, a few factoids:
- During a race, if I don't take extra salt before I start, I will have to piss before I jump on the bike. I don't notice this when I'm in the water, and I'm not one of these superhuman mutants who can piss his pants on the bike or run and just keep going, so what ends up happening is I will have a full bladder the whole time I'm on the bike and be ridiculously uncomfortable the whole time, and I will have to wait until I pass a port-a-potty, or I will just duck into the woods on the run course and relieve myself.
- Think about the contents of IV fluid. NS is 0.9% NaCL. LR (isotonic to blood) contains 600mg/100ml of sodium. Why is this?
- When you are doing some kind of athletic activity, whether it be football, futbol, baseball, or some hard-core endurance activity, you are going to have massive vaso-dilation. You are opening up capillary beds throughout your periphery for cooling, and to deliver nutrients, oxygen, etc. to the tissues, and to clear waste products. You need enough fluid to fill all that extra space you've created.
Think of it this way... you're making kool-aid for a party. Your only pitcher will hold one liter of kool-aid, so that is how much you make. But suddenly, it is brought to your attention that you absolutely have to have two liters of kool-aid. Someone brings you a two-liter pitcher. Do you just pour your one liter in, and fill the rest of the empty space with water? No. You have to put in the kool-aid mix, the booze, and the sugar too, or it will be disgusting.
- One adaptation that athletes make to training in the heat: retain salt better. Why is this useful?
Let's look at some of the many uses that sodium has in the body:
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Blood glucose retention via cotransport
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Action Potentials
- Removal of urea from the blood (no link, but it happens)
Simply put, sodium is one of the most important ions in your body. It is important to replace anything you lose through sweat and urination, and you will do both during a freaking 5+ hour training ride.
Some athletes, like myself, will have salt caked on them after a long workout in the heat. You might just be losing excess salt that you don't need, but chances are, you're not. This has to be steadily replaced, or you will start to get hyponatremia. At this point, you can get water toxicity, and you will fatigue and feel like ****, and you will perform poorly.
Most good electrolyte supplements will contain sodium, magnesium, potassium, and calcium salts. They are all important, but sodium will be the most prevalent, because it is found in the highest concentration in ECF. It is important for your ECF to maintain proper
osmolarity.
AAAAAAAAAAAHHHHHHHHHHHHHHHHHHHHHHHHHHHHH!!!!!