Can you train fluid toleration?

January 23rd, 2022
Can you train fluid toleration?

Sounds logical at first. Just like you can train your fat metabolism, why shouldn’t you be able to train the amount of water your body can absorb?

Might be practical when racing in hot and humid conditions, especially for people with ahigh sweat rate. But we shouldn’t forget about the danger of overdrinking and its consequences: hyponatremia.

The actual goal of an increased fluid intake is to bring water back into the bloodstream - where the sweat is originally drawn from – to maintain the blood plasma volume and sustain cardiovascular effort.

But for the fluid to get into the blood, it must pass through the gastrointestinal system and be absorbed via the wall of your small intestine. The stomach is a porter in a way that lets the water get into the vascular system.

In order to optimize your fluid absorption, you can try three things:

  1. Gradually increase the volume of your fluid intake to let your stomach adapt to the new amount of fluid.
    • Because generally, the stomach is able to adapt to bigger amounts of fluids, solids or a combination of both, just like competition eaters use it to their advantage.
  1. Drink hypotonic sports drinks to encourage an increased absorption through your gut wall.
    • Fluids exit the small intestine via osmosis and transport proteins in the wall of you gut. The consumption of glucose and sodium therefore increase the transportable amount of fluid.
  1. Test drinking more, but less frequently to optimize your gastric emptying rate.
    • It is proven that a higher number of fluids or solids in your stomach increases the gastric emptying rate. So, it’s better to drink rarely but much, than often a little, if your body tolerates that during exercise.

But whatever you do, be careful. If you haven’t heard of hyponatremia, this is the moment you should inform yourself.

Because most times, overdrinking is a more dangerous problem, than drinking too little. Especially when racing in hot and humid conditions, athletes tend to drink way earlier than they’re thirsty. They believe that they have to substitute 100% of the sweat they lost. But this is not entirely true. Athletes are provenly able to tolerate a higher rate of dehydration than other people. So rather than flooding their bodies and risking hyponatremia, they should drink moderately and consume electrolytes additionally.

Hyponatremia is a condition that occurs when a person drinks in large amounts and therefore dilute their sodium concentration, which already is lowered because of sweating. This can lead to a cerebral edema with headaches, nausea, tremor and epileptic seizures, if not treated, to death.

To conclude; generally said, yes, you can train your fluid toleration. But its only reasonable if your sweat rate is extraordinarily high while being physically active. For most other athletes, it brings more risks than advantages.

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