Is it possible to overhydrate?

We’re in the middle of summer and it’s getting hot.  Really hot in some places.  When it’s hot and you’re out riding it’s important to stave off dehydration by ensuring you drink plenty of water or electrolyte based sports drink during your ride and hydrating well before and after the ride.  But is it possible to be too hydrated?

 

What’s Overhydration?

When you’re overhydrated you essentially have an excess of fluid in your body which occurs if you drink too much or have a disorder that decreases your body’s ability to remove water.  The result is too much water and too little sodium, known as hyponatremia, which can be dangerous.

However, if your pituitary gland, heart, kidneys and liver are functioning normally drinking a lot of water is not normally dangerous.  You would need to drink 10 litres or more a day regularly to exceed your body’s capacity to excrete water.

Your brain cells are vulnerable in an overhydration situation that causes low sodium levels in the blood. Your brain can adapt when overhydration occurs slowly, but when overhydration occurs quickly, confusion, seizures, or coma may develop.

 

So what’s the right amount of liquid?

You’ll lose about a litre of water an hour during a solid training session or race.  But you can lose up to 3 times that amount if the temperature is high.

Your body can’t absorb much more than about 1 litre an hour and if you try to force more than that in over a sustained number of hours you could do more harm than good.  At least you will need to urinate more often than normal which would be annoying.

For most people 600 to 750mls an hour is about the right intake.  For heavy people, or especially hot conditions, you could increase that by 100 to 200mls an hour.


For anything longer that about 45 mins to 1 hour it’s highly recommended to use a sports drink, like Peak Fuel, rather than just water.  For anything less than that water is fine.  A quality sports drink replaces electrolytes ensuring your sodium levels are balanced and your absorption of fluid is better, plus you get the added benefit of carbohydrate supplying crucial extra energy for more sustained performance.

Taking a few sips every 15 minutes is preferable to guzzling every 30 or 60 minutes and ensures you don’t risk dehydration sneaking up on you.When all else fails listen to your body.  When you start feeling thirsty you need to be drinking to stay hydrated, if you’re not feeling thirsty you’re probably OK.  Just keep these basic principles in mind:

 

1. Start every training session or race well hydrated.
2. Stay topped up with a few sips every 15 minutes.
3. For longer than 45 minute sessions use an electrolyte based sports drink, otherwise use water.
4. Always keep a drink handy.
5. Rehydrate well after every race or training session.