Keeping Hydrated During a Trail Run

Most runners will want to have drinks with them while they are running. These can be carried in bottles or a camelback system.

On less-isolated trails, you can plan to pick up drinks at shops along the way. On the more remote runs it may be possible to drink from nearby streams, but always remember there is a risk of picking up a stomach bug from doing this.

If you decide to carry drinks then you have a range of options, from water to making up a sports drink (or buying a pre-made product).

Matching sports drinks to your needs

Sports drinks come in different guises depending on the amount of carbohydrate/energy they provide. There are three types.

• Hypertonic. These are more concentrated than normal body fluids. While this type of drink provides more energy with less to carry, the higher concentration tends to slow down absorption.
• Isotonic. These have the same concentration as body fluids, providing both fuel and fluid at the same time.
• Hypotonic. These are less concentrated than body fluids and tend to be better when fluid replacement is the priority.

In most circumstances, an isotonic drink (which contains 4-8 per cent carbohydrate or 4-8 g per 100 ml) is best when exercising if you want to take in both fluid and fuel, although in the heat you may want a lower concentration to help increase the rate of absorption.

If it is fluid replacement that is key, then a hypotonic drink should be used. The added electrolytes and sugar in this mean it is absorbed faster than plain water.

Hydration goals

It is unrealistic in endurance events to expect complete fluid replacement while exercising. Rather, you're aiming to limit fluid losses.

We also know from scientific studies that there is a limit to how much fluid can be absorbed from the gut: around 800-1200 ml per hour in normal conditions.

Ideally you should have some idea of how much you need to drink. Base this on whether you are a heavy sweater or not and the likely temperature during the day.

Recovering from a day's run

The most important thing to do once you have finished running for the day is to start the recovery for tomorrow.

First, get yourself into warm, dry kit. As soon as you stop running, you start to chill, even on mild or warm days. Standing around in damp kit has the potential to increase the risk of picking up a cold or similar due to a weakened immune system - not what you want at the start of a week's running holiday!

Secondly, aim to consume a mix of 50g carbohydrate and 10g protein in the first 30 minutes after exercise. This is the time when our bodies are most receptive to starting the internal recovery process. Eating replenishes our glycogen stores, replaces fluids and electrolytes, and repairs muscle damage.

Thirdly, aim to drink 150% of the liquid you have lost during the day over the next five to six hours. This should not just be water but should contain small amounts of electrolytes (in particular sodium) both to enhance absorption and to replace those lost during exercise.

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