5 top hydration tips for long distance runs

Staying hydrated is incredibly important – indeed, most people would face serious illness without access to water for more than a day or two. But do you know how much you should drink when running? 

When we exercise, we need to drink more fluid than usual, so taking the time to think about how you hydrate when running is a smart move. In this blog, you’ll learn all about the importance of hydration when running, then we’ll explore five handy tips to boost your hydration game.

Reminder: Why do you need to hydrate when exercising?

When you exercise, your body literally warms up. However, to work properly, you need to maintain a stable core temperature of around 37.5C. So, your body’s main mechanism for cooling down is to sweat - and that means you’ll lose water. Drinking water and other fluids replaces the water you lose through sweating, breathing and urinating.

If you become dehydrated, then you’ll experience a variety of unpleasant symptoms:

• Headaches

• Cramp

• Nausea (feeling sick)

• Dizziness

• Poor performance

Remember: severe dehydration can be life threatening. 

There are lots of ways your body ‘tells’ you that you’re dehydrated, but one of the clearest signs is the colour of your urine. If your pee is dark, then you’re becoming dehydrated. If it’s clear and light, you have a suitable amount of water in your bloodstream. 

5 tips for hydrating as a runner

The basics of staying hydrated are, by and large, common sense. Still, if you run regularly - and particularly if you’re doing longer races such as marathons - thinking about how you’ll stay hydrated is a good idea. You don’t want to get dehydrated and be taken sick, nor do you want to over-hydrate and be forced to take a loo break mid-race. 

Read our five tips for hydrating as a runner to learn more.

1. What should you drink as a runner?

For most runners, the answer is simple: water! Our bodies have evolved to absorb water extremely efficiently. Water should provide most of your hydration before, during and after your runs. Especially for shorter runs, most people don’t need to drink anything else.

That said, there are times you might want to consider specialist energy drinks. These ‘sports drinks’ are found in most convenience stores, as well as specialist sports shops. Different brands claim to do different things, and provide additional nutrients or ingredients such as:

• Sodium (salt) and electrolytes (minerals)

• Sugars and carbohydrates

• Protein

• Potassium

• Magnesium

• Caffeine

These drinks are often designed to replace minerals you lose while running. For example, when we sweat, our bodies lose sodium (salt), so these drinks can replace those lost minerals.

You might want to consider these kinds of drinks at different stages of your runs. For instance, a drink containing caffeine and sugars might give you a boost in the middle of a marathon, while drinks containing salts and electrolytes can help prevent cramps. After your run, drinks that contain proteins could support your recovery.

It’s also worth considering one of these drinks if you’re doing a lot of training and don’t have so much time to recover between runs. For instance, most people can get all the potassium they need from their regular diets. However,  if you’re doing several long runs in a 24-hour period, you might choose to drink one of these drinks. This is because you may not get enough replacements from your diet.

2. How much should you drink as a runner?

There’s no fixed amount of water people should drink, as it depends on your age, activity level, gender, and local climate. That said, a rough guide would be to drink about one litre of fluid for every 1000 calories you burn in a day (this includes water, but also milk, juices and liquid in food). Remember that while other kinds of drinks have their own benefits, water will provide all the essential fluid you need and should be your main source of fluid intake. 

The average man burns about 2,500 calories per day (so should aim for 2.5 litres of fluid), while the average woman burns around 2,000 (so aim for 2 litres of fluid). If you run, you’ll burn more calories than this, so you need to drink enough to compensate for the lost liquid.

You can use our Runkeeper app to help track how many calories you’re burning while exercising, and then figure out how much fluid you need to take on. If you’re running somewhere hot and humid, or you sweat a lot, then you should drink more.

3. When should you drink as a runner?

For shorter runs (those around 30-45 minutes) you often don’t need to drink while doing your workout – you’ll be fine hydrating before and after the run.

However, if you’re doing a longer race, then a hydration plan is handy.

• Before the race: About 2 hours before your race, drink roughly half a litre of water. This will hydrate you, but give you enough time to wee out any excess your body doesn’t need.

• During the race: Try to top up with around 150ml every 20 minutes or so. If you’re doing an organised race, then you can often just pick up a quick refresher at hydration stations. This is when sports drinks containing electrolytes can be especially useful. 

• After the race: To help recover, you should aim to drink at least 1.5 litres of water for every kilo of weight you’ve lost. If there aren’t any weighing scales at hand, try to drink at least a couple of litres of water in the hour after the run. Drinks containing electrolytes can also be helpful at this stage - potentially helping with recovery. 

4. To plan hydration or not?

There’s a fierce debate among experts about how people should drink when running. There are two schools of thought here:

• a. Drink when you feel like it: This approach is pretty straightforward – you listen to your body and, if you feel thirsty, then you should drink.

• b. Follow a strict hydration plan: In this approach, you figure out your personal fluid loss rate when exercising (by weighing yourself before and after a run, you can figure out how much fluid you lose per hour), then top up the lost amount, during and after exercise.

One study compared these two approaches and found that following a strict hydration plan meant people were more ‘optimally’ hydrated. Nonetheless, the difference in performance was minimal, so it’s up to you. If you prefer knowing you’ve got the exact amount of fluid then follow the strict approach. If you’re happy listening to your body, that will likely work in most scenarios.

Whatever approach you take, don’t try anything new on race day - stick to the plan you’ve been following so you won’t get distracted. 

5. How to stay hydrated during a run

Thinking about how you’ll stay hydrated is an important consideration – especially for longer training sessions or marathons. Here are some strategies to follow:

• Familiarise yourself with water stations: If you’re running an organised race, then there will be water stations dotted throughout the course. Check the route map in advance so you know when to expect them. 

• Invest in a camel pack: Camel packs carry water and have a sip tube which you can drink from as you run.

• Carry a water bottle: While carrying a water bottle isn’t always ideal, especially for longer runs, it works for some. Choose an easy-to-hold bottle which lets you drink through a straw to save opening the lid. You might also want to invest in a bottle belt to keep your hands free. 

• Plan your route for water stops: Especially during training runs, you can plan your route to include water stops. Perhaps you know of a public fountain that’s accessible on the street – build your run route around this. Alternatively, work out a round route which can take you via your home or your car to get a top up. 

• Buy drinks: If all else fails, carry some cash or a card with you and buy a replacement water as and when you need it.

How the body absorbs water

When you drink water, it is absorbed through most of your digestive system and crosses over into your bloodstream. That said, most of it enters your bloodstream in the small intestine and takes as little as five minutes to get there. Other fluids tend to take longer to absorb.

How to rehydrate quickly

There really is no better way to rehydrate quickly than to drink plenty of fluids. Water is the best – not only is it free (or cheap), but your body is perfectly primed to absorb it. That being said, if you are suffering from dehydration, you might want to consider drinking a sports drink in addition to the water. This is because it will quickly provide you with sodium and other electrolytes you might have lost through sweat.

By and large, hydrating for your runs is fairly straightforward. In most cases, it’s about listening to your body, and watching out for signs of dehydration. Remember staying safe is more important than anything – even a PB! At ASICS, we provide a range of bottles, bags and other running accessories to help you hydrate when running.