How to stay hydrated while running a marathon or 10k

Running hack: how to hydrate properly during a marathon to feel full of energy

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How you hydrate when running is one of the most important parts of feeling energised and happy. If you’re running this year’s London Marathon, then having a hydration strategy is vital… but it’s equally necessary if you’re attempting your first 10k. Here’s how to hydrate your way to the finish line.

When you’re running something as long as a half or full marathon, it’s the small things that can make a massive difference. The socks you wear can be the difference between blisters and happy feet. How you tie your shoes can either cause or prevent black toenails. The food you eat the day before will impact how much energy you have, while the kind of breakfast you choose will either leave you feeling ready to run or swallowing down undigested globs at mile five.

Arguably one of the most important aspects of long distance running, however, is hydration. We’ve spoken loads on Strong Women about whether you really need to drink eight cups of water a day, how dehydration can impact mood, and whether cold or warm water is more hydrating, but knowing when and what to consume to stay topped up while running is a real skill.

The problem is that with long distance running, you often don’t know what you need until it’s too late. The body is in such a state of inflammation that it can be hard to work out when you’re hungry or thirsty and by the time you’re able to distinguish those signals, you’re probably significantly dehydrated and energy deficient.

“Our thirst sensation can be suppressed during exercise, meaning we may become dehydrated before we feel thirsty,” explains Kat Shaw, Lucozade Sport’s hydration expert. “Don’t leave it too late to start drinking, start taking on fluids early on in the race.”

It’s not just that feeling hungry and thirsty is distracting; dehydration can seriously impact your performance on the road. According to a 2011 study published in the Journal of Athletic Training, 70% of half and full marathoners believe that dehydration has negatively impacted their performance on race day. It’s worth pointing out that most of the participants surveyed lived in hot, humid parts of the US so potentially fewer would say the same in the UK but the fact still stands that many of us do suffer from dehydration.

That can lead some runners to overdo it on the water. A recent review published in the journal Nutrients says that dehydration and overhydration are the two main issues when it comes to endurance exercise. While low levels of either may only cause minor blips in performance and wellbeing, at moderate-to-severe levels, they can lead to serious illnesses and/or very reduced physical capacity.

To help, we asked Shaw to share her nine tips for staying hydrated during a marathon (or shorter distance) in order to stay energised, happy and motivated.

10 tips for staying perfectly hydrated while running

These tips are great, whether you’re running a 10k, half marathon, marathon or ultra. You don’t have to be a marathoner to benefit from good hydration practice! Simply adapt Shaw’s guidelines to suit the distance you’re doing. Celebratory post-race beer not included.

  1. Sip in advance. In the week before the race, keep some water with you and take small sips frequently throughout the day so that you stay well hydrated.
  2. Check your pee. First thing in the morning on race day, check your pee colour. You ideally want it to be a pale straw colour; any darker, and you need to drink more water before leaving to get to the start line.
  3. Drink more in the hours before the race. “It’s recommended that runners drink 5-10ml per kg of bodyweight in the two-to-four hours before the start,” says Shaw. If you weigh 65kg, that means that you want to be drinking anywhere from 325ml to 650ml – at least half of a big bottle – of water at least two hours before you plan to start running. “Use your pee colour to determine if you need more to the higher end or lower end of this range.”
  4. Top up with electrolytes. You may have several hours between first waking up in the morning and crossing the start line, during which time you’re going to have your breakfast and coffee. Shaw recommends keeping a bottle of Lucozade Sport to hand during this time to help keep your fuel tank topped up as it contains carbohydrates and electrolytes to enhance hydration and help maintain endurance performance.
  5. Sip regularly throughout the race. “Sip little and often throughout the 26.2 miles to help your body absorb the fluid without you needing to stop to go to the toilet or giving you stomach discomfort,” Shaw advises. You definitely do not want to glug down a load of fluids at any one point!
  6. Go between water and gels. At races like the London Marathon, there are plenty of water and hydration points. At this year’s race, Lucozade Sport drinks can be found at miles nine, 15, and 21, along with their dual-fuel energy gels at miles 14 and 19.
  7. Take on water with your gels. If you’ve been training with gels, you’ll already have a few with you on race day. If you’re planning on consuming Lucozade Sport gels, however, the brand recommends picking up some water to have alongside them as that can help with their palatability while also contributing to your hydration needs.
  8. Don’t neglect sports drinks. “We recommend consuming a combination of water and sports drinks throughout as you will also lose electrolytes in sweat, in particular sodium,” says Shaw. “If we do not replace the lost sodium, you may be at risk of developing hyponatremia, where the body’s blood sodium levels drop too low. Consuming water alone will not replace the sodium we have lost.” If you’re planning on bringing your own fluids, check out our simple guide to making your own electrolytes.
  9. Focus on rehydrating at the end. Once you finish running, it can be difficult to think about consuming anything – but you need to start rehydrating as soon as possible to get the body back to functioning properly. Shaw says that you need to consume around 1.5 times the amount of fluid that you’ve lost through sweat little and often over the following 24-48 hours. 

Again, you’re probably not going to know how much you’ve lost when you’re standing at the finish line, so the best thing to do is be conscious of how often you’re peeing and what colour it is. If you’ve run a five-hour marathon and haven’t peed for six hours, it’s probably better to prioritise pints of soda water initially by the time you make it to the pub!

Enjoy a quick mobility session to help you feel loose and limber ahead of your race, with one of our 15-minute mobility classes.

Images: Getty

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Miranda Larbi

Miranda Larbi is the editor of Strong Women and Strong Women Training Club. A qualified personal trainer and vegan runner, she can usually be found training for the next marathon, seeking out vegan treats or cycling across London on a pond-green Tokyo bike.

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