Long distance runners are at much higher risk of hyponatraemia (electrolyte imbalance) than of de-hydration and this can cause nausea, vomiting and even be potentially fatal. There are apparently no reported cases of people dying from de-hydration in any world marathon or Ironman event, but a significant number have died of hyponatraemia. The cause is normally that people drink too much water and so dilute their concentration of electrolytes with potentially fatal results. When exercising it is important not to drink too much water and to try and maintain the body's electrolyte balance.
High5 Zero come in tubes of twenty tablets and each tablet will when mixed with water make 0.5 to 0.75 litres of electrolyte solution. The tablets are quite hard and maintain their shape and consistency even when the tube is dropped. They are scored down the centre to make them easy to snap in half, this make it possible to drop them into a bottle with only a think neck.
One of the best features of these tablets is their taste. They are really refreshing and not sweet or sticky like some others. The orange and the berry flavours are my favourite; the orange flavour is perhaps a little stronger than the berry. They taste good even at room temperature - even in the sauna (but doesn't any drink taste good in a sauna?)
The tube is robust and easy to carry. This makes them easy to take on holiday or to go hiking with. I did used to suffer periodically with cramp when I was running which is what prompted me to try these. I don't suffer with cramp anymore and I don't think that this is simply a coincidence.
The tablets may seem a little expensive but in fact when you consider that a single tube will make 10-15 litres of delicious tasting electrolyte solution the cost seems far more reasonable.
My only reservation is than an average person will sweat at the rate of around 1 litre per hour during extended exercise and that sweat will contain approximately 900mg of sodium. Each High5 tablet contains 260mg of sodium, 75mg of Potassium, 60mg of Magnesium and 9mg of Calcium, and so a single tablet in 0.5l of water would still result in sodium levels becoming depleted during longer races. For such long races you would probably need two tablets per 0.5l to mitigate this more fully.
I will still give these tablets a considered five stars for their taste, efficacy and ease of use. It's no drama to put an extra tablet in the bottle for longer periods of running.