Don't Dehydrate. Rehydrate!

Wonderful James came running with me yesterday. You can read about that run in my TRAINING bLOG if you're curious.

The day before yesterday I learnt about dehydration and heat stress. One of the things I learnt was that after exercise we should aim to replace our fluid loss through sweating by 150%.

Naturally, I was curious to see how much fluid James and I would sweat out during a 10km run. So we weighed ourselves before and after the run (note: 1L water weighs 1kg, hence weight loss is a good estimate of amount of fluid lost from the body during exercise).

I was so surprised to find out the results! I lost 0.9L of water, and James lost a whopping 1.2L. I was expecting much less - maybe, oh I don't know... 0.4L for me?

Therefore, to adequately rehydrate post-exercise, James and I needed to drink 1.8 and 1.4L of water respectively.

Now I know for a fact that I am a person who doesn't sweat very much - not only am I female, I also don't seem to work up much of a sweat, even compared to other females. So if not-very-sweaty me can sweat almost 1L of water during a 10km run in cool-to-warm conditions, you can see how easily many of us can become dehydrated due to prolonged exercise and not enough fluid intake during and after, especially in warmer conditions.

Dehydration is not good. You cannot train your body to tolerate dehydration better. With training, other aspects of your bodily functions will improve, e.g. your body might sweat less. But you will never tolerate dehydration better.

So be sure to adequately hydrate your body before, during and after exercise.