Did you know that drinking water can kill you ?
Drinking water doesn’t replace sodium
Most people who exercise vigorously (i.e. enough to actually build up a sweat), know it’s important to drink plenty of water to keep their bodies hydrated.
When you’re exercising really hard and sweating like a pig……
you’re not just losing water but sodium.
Drinking water is replacing the water BUT not the sodium. When you lose too much sodium you end up with hyponatremia.
Hyponatremia causes a long list of problems ….
- Vomiting
- Loss of appetite
- Headache
- Restlessness/fatigue
- Abnormal mental status (hallucinations, confusion, change in personality, etc.)
- Muscle weakness
- Convulsions
Untreated it can result in DEATH.
The moving salt lick
Salt is excreted through the skin, making you taste like a salt lick and act as a beacon of happiness for all the salt starved insects in the neighbourhood.
You enjoy a long cool drink of water in response to the burning thirst, brought on by the profuse sweating. The water quickly floods into the blood and begins to move into the tissues rehydrating the cells.
But the cells are now a little low on sodium because they donated it to the “lets keep the dude cool fund”.
Osmosis replayed
Water moves from a “high concentration” to a “low concentration” until the “water concentration” is balanced.
So if there is less sodium in the cells, the water is going to want to move into the cells. It keeps moving in until the cells are stuffed with water.
Most cells don’t mind feeling a little bloated for a short period of time, but cells in the brain have a big constraint. The cells are stuck in a hard casing i.e. the skull. So things get a little squashed in the brain box. The swelling cells just can’t fit and so they stop working leading to the hyponatremia problem.
What to do if you exercise vigorously
If you exercise seriously (again let me remind you this is not running for the bus but actually exercising hard enough to generate some sweat), rethink the healthy living lifestyle advise of cutting salt.
When exercising, don’t guzzle down water – stick with the basic guideline of a cup of fluid every 20 minutes.
If you’ve participated in an endurance event and you’re feeling a little flat, don’t assume these symptoms are due to dehydration and guzzle more water.
Consider replacing some of the fluid with one of those fancy sports drinks (check it has salt in it and is not just coloured sugar water).
Salt is a two edge sword
Too much can kill because it leads to cardiovascular disease but too little can also kill.
A sobering statistic 15 – 20 % of people admitted to hospital in the UK have hyponatremia.
So after a good workout, enjoy a guilt free salty snack.
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Further reading
Chocolate milk is the best sports drink on the market | For big decisions bringing in the bladder to “help” the brain is best | Mother nature can handle salt |