I C&P'ed this excerpt from the Serpentine Runng Club of London's site>>
Some revealing research has been done with WATER BOOSTING before a marathon. Twenty-three marathoners were asked to run the marathon with and without water-loading. ALL of them ran 20-seconds a mile faster with water-boosting.
The procedure was:-
Four hours before the race drink 8oz glass of water every 15 minutes.
Stop one hour before the event but drink another two glasses between 30 and 20 minutes before you start. You will pass urine in the last minutes up to the gun.
Take on water at all feeding stations.
Don't worry about urgent loo visits. You will pass 50 oz of urine during the four hours, but you will be pre-hydrated by some 40ozs and if you have carbo-loaded you will have another 46ozs. That's a total of 86ozs to combat sweat loss which can cause a 5 per cent drop in bodyweight. This method restricts weight loss to 2 per cent. Try it out in training before your long run several times before the big day.
If you like running, you will like it more if you get better at it. This requires leaving no stone unturned. Be able to say 20 years hence, "You know, I gave running my best shots. I surprised myself. I achieved what I thought I would never achieve - I felt I had done something special."
by Frank Horwill.
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Comments please.