Adding salt to drinking water? (Read 4474 times)

Here is the problem. Your sweat contains salt. The reason why you sweat is that it is one of the best ways that your body has to cool itself. Essentially, the wet sweat on your skin cools your skin down as it evaporates. The salt is in the sweat as a result of the mechanism your skin cells use to get the fluid out into your sweat glands; the cells cannot push out pure water but they can push out salt, which carries water. Anyhow, as a result of all this, you sweat out salt water. Sweat contains between 2.2 - 3.4 grams of salt per liter. A liter of sweat weighs 2.2 lbs. So, for every pound of sweat that you lose, you put out 1-1.5 grams of salt. In the Summer heat, most folks sweat a pound during every mile or two of running. Well, when that sweat evaporates, the salt is left behind, since it cannot evaporate like water does. On windy and dry days, the water evaporates more quickly, and your body replaces it with more sweat more quickly. So you get more salt on you. On still, humid days, the sweat evaporates less so you sweat less (and feel hotter), so you get less salt on you. The reason why people get hyponatremia (low blood salt) is because they sweat out fluids that have a high concentration of salt and replace it with fluids that have a lower concentration of salt. Gatorade and other sports drinks have far less salt in them than sweat. So replacing your sweat with sports drinks does not work. For example, to replace the 1 gram of salt (sodium chloride) lost through a half liter of sweat, you would need to drink a whole liter of Gatorade. That is a half liter of extra water, which dilutes your blood salts. Them Jelly beans had salt in them. Gu packets have salt in them. In general, these do not have a lot of salt. Most have about 50 mg of sodium, which is equal to about 20 mg of salt. There are 1000 mg of salt in a gram. So you would need to take 50 gu packets or equivalent to replace a half liter of sweat. Most people cannot fathom eating nacho chips, potato chips or pretzels during a marathon, but these are commonplace to ultramarathons. Many people do eat a lot of salt in the days leading up to the marathon, or carry salt tablets with them during the marathon. Just in case. The Medics should also have salt tablets. You cannot salt-load like you carb-load because your kidneys efficienty remove excess sodium, but you can make sure your reserves are replenished. A good Mexican meal 3-4 days before your marathon, and there you go. Eat the whole basket of chips

Ok, so assuming I am slow and female (yeah), would I be smart to use that Gatorade endurance stuff for my marathon? I am a VERY heavy sweater and it could be pretty warm in early Oct. Or is it really only a major risk if I am drinking only water and have more risk factors?

Preload with salt. Do not preload with water. At all. Take salt tablets with you, consume them if you start to get weak, dizzy or nauseous. Drink only the sports drink.

The possibility of going hyponatremic from too much fluid at a marathon is significantly lower than at an Ironman.

Only because of the time factor. Ironman triathelons take longer and so there is more sweating and fluid comsumption.

Listen to your body some too. When I ran phoenix it was warm (at least compared to what I was used to ) and I met ALL of those requirements except possibly the fluid intake. Hard to say. 5 1/2 hour race, overweight, undertrained etc. I did carry my camelbak which is about 40-50 oz of dilute gatorade and take in water on the course. so took in a lot of fluids. Nobody was talking much about hyponatremia yet. Partway through the thought of another gu started to make me queasy. Someone had pretzels and they were soooo freaking good I though I would cry. I swore I would carry pretzels with me if I ever did another marathon...although by portland I didnt feel the need to (not hot). If it were hot I would probably carry salt packets or tablets. It sounds gross, but at mile 20 in phoenix they had little fast food salt packs and I broke one open and ate it and it tasted good.

Do not preload with water. At all.

Everything I read says to hydrate because a bolus of H2O will help the body absorb carbs injested on the way. Just an interesting counter view point. I guess there is something to looking at what is your risk factor. I just have to make sure I am faster than 4 hours now dont I Well zoomy - I guess neither of us fall in to that "too big or too small" category - one bonus for not quite hitting our target yet.

The real point I am making about preloading with water is that one should not water load the way you carb load. Any excess water you take in will go straight into the toilet and will take salt with it. Back to the start of this thread. Many folks drink 2-4 extra liters per day in the week leading up to the marathon. That is unnecessary and possibly deadly. In anything less than hot conditions, you can start out on even the dry side and hydrate as you go. It is better to finish a touch dehydrated than overhydrated. The former is uncomfortable. The latter can be fatal. If you are more comfortable drinking a liter of fluid on race morning to top off the tank, go for it. But do not water or fluid load. If anything, salt load.

Oh goody....I am really bad about hydrating the week before. Glad to know I was being smart! I do like my fluids right before a race though...nerves give me dry mouth Man between telling me to eat my salty food and not to worry about pre-hydrating Trent really is my new best friend. If you tell me that I should eat chocolate and Ice cream more often I may swoon.

Eryn is gonna really love you now, Trent. I think Chocolate ice cream is her favorite food.