Avoiding dehydration - riding in hot weather

It always seems to happen. One week I'm riding around wishing I had the heated jacket plugged in, then we get a few days of "scorchio" weather and I'm struggling to stay cool.

Temperatures over the weekend and early in the week hit the high 20s and humidity went through the roof. Monday in particular was very uncomfortable on the bikes. One of the main dangers of the unique combination of overheating and the cooling breeze we're generating as we ride is a high risk of dehydration.

Dehydration occurs when the body tries to maintain a steady temperature of around 37 degrees by sweating. The result is that body fluid and electrolytes vital to the function of the body's organs are lost. One of the best signs that you are dehydrated is not that you are thirsty but that you don't need a pee! If you ARE thirsty, and have dry lips and a dry mouth, you are well into the first stages of dehydration.

What are the dangers of running short of body fluid? In the early stages, you just get fatigued and lose concentration. In the later stages more serious confusion can set in, as well as heat stroke. Most UK riders are oblivious to just how real a problem this is - in the US where they ride long distances in hot conditions, they are much more aware of the risks.

So what can you do to prevent dehydration? Planning ahead is the answer. Start by drinking before you go out. For sports like cycling and soccer, it's recommended that you drink around 500-600ml of fluid a couple of hours before you begin. Then around 15 minutes before you set off, drink another half litre.

Once on the move, you need to keep replenishing fluid, so you need to either stop and buy something, or take a bottle with you. For sportspersons, the recommendation is that you take around 100-150ml (about 1/5th of a cycle bottle) every 15 minutes or so.

OK, now this may not be entirely straightforward on a motorbike, but particularly on group rides there are usually short breaks at regular intervals, so use the opportunity to top up, and if you are doing it right, you should be making a loo stop too. You should certainly drink something when you stop for fuel, and if you have a 250 mile tank, you should definitely make intermediate stops - remember, if you feel thirsty, you are already dehydrated. And don't forget to top up when you stop too - this will improve your recovery time from fatigue.

Any cycle shop will sell you a bottle for under a fiver and they are unbreakable and will squash - the plastic bottles with Evian, Volvic etc. are liable to split and leak. A few quid more will buy you an insulated plastic cycle bottle - bung some ice cubes in it and you have cold drink for a couple of hours.

A neat alternative is a Camelbak or a cheaper copy. These are plastic bladders that slip in a pocket or are worn in their own backpack which hold a couple of litres. They have a plastic pipe which you can stick in your mouth and suck when thirsty. With one of these you can stretch your other stops a bit further.

So what to drink?

The one thing you need to steer well clear of is alcohol. It might be tempting to sink "just one cold pint - I'll be well under the limit". The alcohol will be absorbed faster, and even more disorientating than normal.

I'm not fond of fizzy canned drinks because they are too sweet and sticky. Remember that coffee in particular and tea to a lesser extent are diuretics (ie they make you pee more) but they are better than nothing at all - at least they can top you up again!

A big fuss is made about isotonic fluids - these are basically water plus the electrolytes you lose in sweat, so they have the advantage of keeping the chemical balance of the body right. Lucozade Sport is one example that you'll find in most service stations, or Gatorade if you happen to be Stateside. Isotonic drinks also come in powder form - you can buy tubs of the stuff from any cycle shop and make up a couple of litres for the ride.

However, they all cost a lot more than plain tap water!