Staying hydrated and drinking plenty of water during exercise is incredibly important, but how do you know when you’ve had enough? Here’s everything you need to know about H20 and exercise, from SportsShoes in-house nutritionist, Lucy McCrickard.
So, Why Is Hydration Important?
Around 70% of our body is made of water; it’s vital for every chemical reaction in the body. We need around 2-3 litres a day to transport nutrients, help with digestion, to carry out waste and toxins and also to support brain function for mood, energy and concentration.
We lose water and body salts (mostly sodium and chloride) through urine but also when it evaporates as sweat. Even more fluids are lost during exercise, and a water loss of only 1-2% of our body weight can impair performance by around 10-20%!
How To Stay Hydrated ?
Some of the water you need is extracted from food but you should be aiming to drink 1.5-2 litres daily.
Increase this amount if you’re exercising to prevent dehydration. Sports drinks which also contain carbohydrate in the form of glucose can help replenish glycogen stores to boost energy.
Don’t allow yourself to become thirsty – if you’re thirsty, you’re already dehydrated.
Equally, don’t over-drink. This can lead to hyponatremia, when is when sodium levels in the body are depleted to dangerous levels, resulting in confusion, lack of co-ordination – and in some cases can be fatal. Although it takes quite a lot of water to get to this point, it’s good to be aware of it.
When to Hydrate !
We all lose fluids at different rates depending on our levels of exertion but, as a general guide, always start any exercise session well-hydrated, then follow these guidelines according to the duration of your session:
Exercise Under 30 Minutes:
No need to drink whilst exercising, but re-hydrate with water afterwards.
Exercise from 30-60 Minutes:
As above, then re-hydrate post-training with a drink containing both water and CHO.
Exercise 1-3 Hours:
Take a sports drink with you which combines water and CHO. Sip regularly throughout the session – aim for 30-60g CHO per hour. Continue to use the same drink post-training.
Exercise 3hrs +
Choose a sports drink which combines water, CHO and some sodium/salts. Sip regularly, taking on 30-60g CHO per hour and continue to drink post-training.
Check Your Hydration Levels !
There are two effective ways to check hydration levels when exercising.
Weigh yourself both pre and post a session to see how much weight has reduced. A 1kg weight loss equates to around 1 litre of fluid and you should aim to restore levels to your original weight post-training. And check your urine colour: the darker it is, the more dehydrated you are.
Choose The Right Sports Drink !
Commercial sports drinks are designed to offer you a combination of the fluids and salts you lose during exercise and they come with a variety of descriptions.
Sip small amounts frequently and practise drinking as part of your training. Try sports drinks before the event to ensure they agree with you. Most endurance events will tell you which ones they provide during the course of the race.
Contain a small amount of CHO (under 4%). This is lower than your blood plasma concentration and so they are relatively easy to absorb and digest.
Contain 4-8% CHO and also some salts, which is similar to the concentration of the blood plasma, so this is a better choice for replacing fluids rapidly during prolonged exercise.
Include a higher concentration of CHO at over 8% but do not include salts and are sometimes used for refuelling glycogen stores post-exercise. They can also be used during endurance events but should be combined with isotonic drinks to ensure salts are also replenished.
Sports drinks can easily be made at home and are much cheaper than buying commercial brands. An isotonic drink you can make at home is:
200ml of fruit squash
A pinch of salt
Mix together and cool in the fridge.