As soon as you start sweating, you lose minerals. Sport drinks can partly compensate that loss. Always drink a few zips so that both liquid and minerals stay healthily in balance in you body. It is always good to drink water in small amounts when training. One disadvantage with sport's drinks, is that they are sweet, so they tend to make you even more thirsty.
Be sure you don't drink too much at once, it can create cramps or discomfort.
In a one hour Tae bo lesson, I usually have 1 or 2 short drink breaks. I recommend to only have a few zips, not a whole 500 ml at once!
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Extract from a short interview with Haaije Pijl