Sodium is an important supplement to take when it comes to endurance training and hydration. Specifically, sodium is an electrolyte that helps ensure proper hydration status when you consume fluids. Its main job is to help your body retain the fluids you drink rather than just pee it out. Again, I ask who has had to pee a lot when they try and hydrate? Rather than lose the water you’re ingesting, the sodium helps your body retain it in the blood and cells.
Remember the discussion about increasing blood plasma? You need to be properly hydrated in order to have enough fluid to increase your blood plasma volume. So not only do you have to drink adequate fluids to increase the blood plasma, but you need to make sure the fluids stay in your bloodstream and not get filtered out of your body. Sodium is responsible for keeping the fluid inside your body and maintaining an elevated volume of blood plasma.
Think of it like this: if you want to go on a road trip you need gas in the tank. But What if there are holes in the tank? You’d run out of fuel quickly and have to keep stopping to fill up. Sodium is what prevents the holes from leaking essentially. Proper sodium with water ensures fluid → → blood plasma as opposed to → kidneys and bladder.
A proper balance between electrolytes and fluids is necessary to maintain hydration. There is an optimal level of both that yields excellent physical performance results. Any one side tipped more and your body will regulate.
Too much water compared to salt? Your body may excrete it in urine (lots of bathroom breaks). Or worse you can really over-hydrate and have not enough sodium (hyponatremia) which becomes a medical emergency. Or conversely, you can have elevated sodium levels for your hydration status and end up sweating the excess salt out. This results in a layer of white salt on your skin or clothes. This is not a “salty sweater.” It simply means you have more salt than needed compared to your hydration levels. So your body is self-regulating to maintain the ratios as desired.
The ideal ratio is ~ 1,500 mg of sodium per liter of fluid consumed. Now that’s for a hot long day of running. Increased humidity will affect the needs of both fluids and consequently salt. On a cool Fall morning maybe you can get away with 800-1000 mg/liter and that is reasonable. A very hot day may result in some additional fluids and salt necessary. Realistically any fluids you’re taking in the day before, during, or after a race should have some sodium in them so you can actually benefit from hydrating.
I’m sure the burning question is ”how do I get all of that sodium?” This is the natural progression and one that is common. Every bit of solid nutrition that exists will have some amount of sodium that will contribute to your target. Unfortunately, it’s not a whole lot. The drink mixes are ideal for that. But in the event that you cannot get out, I have ordered a 2lb bag of sodium citrate from Amazon. 1 teaspoon of that is ~700-1000mg depending on the brand and it makes it much easier in the hot months to get adequate hydration. Just add it to your drink mix! There is a company called Saltstick which has capsules with ~ 200mg each. I usually pop one every 15 min and to maintain some semblance of consistency.
I hope this demystifies the notion of proper electrolytes and how sodium is one of the most important for endurance training. If you have any questions, please let us know.