Feedback - electrolytes in sports drinks?

‘Are the electrolytes in isotonic sports drinks important or is water just as good?’

I pick this one out because sports drinks are marketed very attractively, very scientifically, and the cynic in me thinks… isn’t staying hydrated whilst training just about getting some water into you?

When you sweat, you lose body fluid which evaporates off your skin, keeping your body temperature at the correct level. Sweat comprises of water, but also a mix of essential minerals which include;

• Sodium
• Potassium
• Calcium
• Magnesium
• Chloride
• Bicarbonate
• Phosphate
• Sulphate

These minerals are lost in small quantities, but during long events, they can start to cause problems in their own right. However, for rehydration purposes, ie the fast uptake of fluids, your choice will be water or an Isotonic drink. Rather than go into the science here, have a look at these links. This article over at brianmac.co.uk goes into great detail on the composition of sweat, and the function of different sports drinks. He mentions not going over fluid loss of more than 2% of body weight. Personally I would say this is low for longer events, and the last time I checked I could easily triple this – losing 3 litres plus on a warm day over perhaps just 1.30hrs.

There is a fair amount of detail here on electrolytes themselves at Medicinenet. They also have a very informative article on general dehydration which is worth a read.

So do you really need the electrolytes? This information would suggest really only for very prolonged high intensity work, ie marathons and longer.

What do I do? For training, I hydrate before and after with water and keep an eye of urine frequency and colour. If I am training over about 1.30hr I will probably strap on the Camelbak and fill it with an isotonic sports drink and sip every 5 minutes or so. The sweet taste also helps me imagine all that energy flowing in!