Hydration for Runners

Female runner drinking lucozade

February 1, 2013 // Rachel Ellis

We’re often asked questions by our runners, particularly those who are new to running half marathons, about how much they should be drinking on race day, and sometimes we’re asked about hydration in training too.

So much information

A quick Google search will show you that there is a lot of advice out there – what to drink, when to drink and how much to drink. We thought a blog post might help cut through the overwhelming mass of misinformation and also help runners begin to think about practising their hydration strategy throughout their training; discovering what suits them so that they can feel confident they know what their body will need during training and on race day too. 

A balancing act

Hydration is a balancing act and something that is obviously personal to your own body, and the weather conditions on any particular day.

Extreme dehydration isn’t a desirable state, but it is quite normal to experience mild dehydration at the end of a training session or race, and this can be easily rectified by taking on fluid after you finish.

On the other hand drinking too much can (rarely, but still it happens) lead to something called Hyponatraemia (low levels of sodium in the blood), which in extreme cases can be fatal. There sadly have been fatal incidences of this at UK races in recent years, including half marathons. In milder cases it can still make runners pretty unwell – which isn’t really something you want while you’re training for or running a half marathon.

A rough guide to drinking

With all that in mind how do you know if you’re drinking too much or not enough?  The Runners Medical Resource website(which BATHALF and other leading UK races created to support our runners) says the following:

Fluid lost in sweat must be replaced; otherwise your body will become dehydrated (short of water) and less efficient. Alcoholic drinks and drinks containing caffeine – such as tea and coffee – can be dehydrating. Take plenty of non-alcoholic drinks with you when you run, especially when training in hot weather. Drink enough to keep your urine a pale straw colour. Also, drink plenty of liquids after training – especially after long runs – and practise drinking during longer training runs. You could also try drinking sports energy drinks in training to see if you like them.

Drink plenty of fluids and preferably no alcohol in the two days before a race. DO NOT drink excessively before, during or after a race, as you may get hyponatraemia

During training

Don’t turn up at the gym or go for a run dehydrated, you should be fully hydrated prior to taking any exercise. Dehydration is easy to detect, when you pass water make sure that it is as clear as possible. The darker the colour of your urine, the more dehydrated you are. Also the frequency with which you pass urine can indicate whether you are drinking enough, if you only pass water once or twice a day it’s time to consider drinking more fluid.

So what should I drink when I am exercising?

When you are exercising for less than an hour; water or a hypotonic drink such as HIGH5 Energy Gel Aqua (a drink providing more water than carbohydrate) is the best to take. This is recommended for people who are at the gym or running for less than an hour. If you are unsure about whether you have had enough fluid before you exercise, try to keep a ‘drinking diary’. This will help you remember to keep hydrated and maintain your fluid intake throughout the day before you exercise.

Drinking on a race day

Start a race well hydrated by slowly drinking up to half a pint (250ml) of water or HIGH5 Energy Gel Aqua in the half hour before the start. Do not be greedy and take extra drinking water from drinks stations during the race to pour over yourself, as you may be depriving slower runners of much needed drinks. Only take water if you need a drink. If it is unduly hot, additional water will be provided and showers will be set up on the race course – so use these to cool yourself, rather than using drinking water.

Although it’s never been hot enough for cold showers to be set up at the BATHALF we have had a couple of surprisingly warm days in past years which have affected many of our runners. Although runners are currently battling snow and ice to do their training, the weather could be much warmer come March and you will need to make sure you have an idea of how much fluid you should be taking on board in warmer temperatures.

Your drinking needs for a race will vary according to your build, your speed and above all the weather, as these affect how much you sweat.

Faster runners (for example, runners who are aiming to run at 8min mile pace or under) on a warm day may need as much as a litre of fluid per hour (two pints). Slower runners should need less – particularly on a cool day – and should not drink more than 500ml per hour.

There will be frequent water stations on your race route, but YOU DO NOT NEED to drink at each one. Instead, just swallow a mouthful of water occasionally. If you like HIGH5 Energy Gel Aqua, and have tried this in training, have one of these instead of or as well as water.

At the BATHALF we alternate our drink stations bottled water : at 2 miles, 5 miles, 8 miles, 10.5 miles and 12.5 miles, and HIGH5 Energy Gel Aqua  (orange flavour) : at 4.5 miles. Further water and energy drinks are provided after the finish of the half marathon and family fun run

Please try to safely dispose of your bottles: drop them onto the roadway along the side of the kerb away from other runners and leave the caps off as this helps the clear up. If you can, drop them at the next drink station. Don’t throw them into hedges, verges or gardens – throwing them can also injure volunteers & runners.

After finishing a race, DO NOT drink large amounts of water. You can only rehydrate (replace lost fluids) gradually over the next 24-48 hours. Eat some salty food as well as spacing out your drinks; by doing this you will not get hyponatraemia and will replace the water salt and glycogen lost when running the race.

Sports Drinks
Some of our runners on Facebook asked specifically about sports drinks. The really important thing to say is if you haven’t trained using a sports drink such as HIGH5 Energy Gel Aqua, then race day is not the time to try something new.  What you decide to drink is a personal thing – many runners like drinking water alone where as others like to drink sports drinks  some like a little of each. If you would like to try using drinks other than water then please do try them in your training.

We hope that you’ve found this information useful – looking forward to seeing you all on race day.