What are they?
Hydration drinks are a mix of water and electrolytes (such as sodium and potassium) with little or no added carbohydrate, designed to replace the fluid and salts lost during exercise.
Why use them?
As core temperature rises during exercise the body compensates by sweating, creating a loss of water and electrolytes, with additional water lost via respiration. Although the body can cope with small changes in fluid volume, large sweat losses can lead to dehydration, which results in impaired performance, increased heart rate, reduced heat tolerance and lower reaction times.
The loss of electrolytes in sweat (primarily sodium) is also exacerbated during prolonged exercise or in hot weather. Failure to replace electrolytes, or dilution through excessive intake of plain water can result in hyponatremia (low levels of sodium) leading to muscle cramps, lethargy, nausea, headaches and in severe cases, death.
Hydration drinks prevent dehydration by replacing fluids and electrolytes. The addition of sodium also facilitates hydration as it stimulates thirst and also water absorption from the intestine, promoting fluid retention. Due to dilution of electrolytes, plain water may also suppress thirst, while hydration drinks maintain desire to drink.
How do I use them effectively?
Generally speaking, a specific hydration product isn’t necessary if you’re riding for under an hour, but they can be useful in maintaining hydration in hot conditions, or if sweat loss is high.
If you do choose one, the rule of thumb is to start your ride well hydrated, and to adopt a regular pattern of drink intake, aiming for 125ml every 15 minutes. This will help to maintain fluid balance.
Remember that if you’re riding for over an hour, you’ll also need to take carbohydrate on board, as hydration drinks don’t contain enough carbohydrate to boost endurance.
Are they better than real foods?
Flavoured beverages increase your desire to drink, and fluid consumption is more closely matched to sweat loss when athletes are offered a flavoured drink over plain water during exercise. In hot and humid conditions they’re an effective way to maintain adequate hydration, although during longer rides you’ll need to consider a carbohydrate source.
On the downside, these drinks can be expensive, and in rides lasting under an hour in relatively cool conditions, good old water will do the job nicely. If you’re not a fan of plain water, you can add a bit of squash and a pinch of salt to your water bottle to increase motivation to drink.
Nuun Active Hydration
£24 for a 4 pack
Full of electrolytes with no sugar or carbohydrates.
H2Pro Hydrate 1000
High sodium content for extreme sweating and has zero calories. Not a source of carbohydrate.
SiS GO Hydro Tablets
Full of all the essential electrolytes, with virtually no calories, and very little carbohydrate.
The original version of this article was published in the April 4 2013 issue of Cycling Weekly magazine