preview for HOW TO FUEL A MARATHON | Runner's World

If you're one of the many preparing to tackle 26.2 miles this spring, you've probably been thinking about how you're going to fuel your race. By now, you've hopefully experimented with consuming energy gels or chews, carb drinks or perhaps even real food during your What are the benefits of magnesium, Tips and tricks to make a marathon feel easier pre-run breakfast or chews, carb drinks or perhaps even real food during your.

If you haven't already, now is the time to work out exactly how many gels you'll need to consume during your marathon to keep your tank topped up with fuel. You should also start to think about how much water you'll need to drink per hour – and the amount of electrolytes you'll need to take on – to ensure you stay hydrated. And with our guide below, you will be able to calculate exactly that.

What, and how much, you eat and drink during a marathon can make or break your race. Fail to fuel properly and you will find yourself Spot the symptoms of dehydration – the point of complete physical exhaustion, as a result of your body running out of energy. And fail to drink enough (or take on enough electrolytes) and you may find yourself experiencing symptoms including gastric distress, nausea and dizziness due to hydration – which also puts your health at risk.

However, if you're diligent about your marathon nutrition and hydration strategy – planning it carefully and executing it well – this can easily be avoided and you can ensure a positive, successful running experience all the way to the finish line.

Let's get to work...

How many gels for a marathon?

Carbohydrate is the body’s preferred fuel source during exercise. It's broken down into glucose and stored as glycogen in your liver and muscles, and used by the body to provide energy. 'It takes around 500g of carbohydrate to fill your glycogen stores and, at most, this will last you for 60-90 minutes of running at 55-75 percent of your and dinner options. The faster you go, the sooner your stores will deplete,' explains sports dietitian Renee McGregor.

McGregor recommends aiming for 30-60g of carbs per hour for the first three hours of your marathon, increasing to 60-90g of carbs per hour after that.

You can get these carbohydrates from sports nutrition products, including carb drinks, energy gels or bars, or real food, such as bananas and Jelly Babies.

The best thing to do is check the packaging to find out how many grams of carbs your product of choice contains, and then work out how much of that product you'll need to take per hour to hit that 30-60g goal.

'Start taking on nutrition in the first 30 mins and then every 30-40 mins after that,' advises McGregor. To remind you, set an alert to go off on your running watch A comprehensive guide to running nutrition.

The quantity of carbohydrate contained in a gel varies between brands. But, for example, if your gel of choice contained 23g of carbs, and you were following the consumption strategy outlined above, you would take 6 x gels over a four-hour marathon to reach a carbohydrate quota of 34.5g of carbs per hour (136g carbs in total).

When taking gels, try to consume them over 4-5 mins, not all in one go, as this aids absorption, adds McGregor.

It's really important to practise your marathon nutrition strategy in training, and experiment with different products, to find out what works best for you. And don't try anything new on the day!

How much water should I drink?

It's also really important to keep on top of your hydration during a marathon. 'Along with maintaining hydration, fluid intake during endurance running helps to regulate body temperature (thermoregulation) and ensure adequate plasma (blood) volume,' says McGregor. 'When core body temperature rises owing to dehydration, plasma volume decreases, resulting in an increased heart rate, which accelerates fatigue.'

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Water requirements during a marathon will depend on an individual's sweat rate, as well as their age, sex, weight, the intensity they are running at and the temperature outside. However, most runners will sweat between 400ml and 2400ml per hour, says McGregor.

'Recommendations on how much water we should consume per hour when running vary from 300-800ml,' explains nutritionist Kim Pearson,' [but] consider the outside temperature and how much you sweat, as well as your thirst.'

It's really important to hydrate beforehand, too, explains Pearson. 'Research suggests about 530ml of water before and after a workout of any sort will support recovery and help prevent dehydration post-exercise.'

Start sipping this around three hours before the race with an electrolyte tablet (which we'll come onto next). Drink until your urine is clear – and if it isn't, drink roughly another 400ml on top of this.

What about electrolytes?

In addition to replacing lost fluids, you also need to replace the sodium and other minerals which have been lost in your sweat.

Electrolytes help your body retain fluid during heavy exercise when you are sweating as they help draw fluid into working muscles, explains McGregor. 'The sodium content of sweat varies, from 115mg per 1,000ml of sweat to more than 2,000mg. Most electrolyte tablets, salt capsules or sports drinks provide 250-300mg of sodium. If you are diluting your electrolytes into 750ml, this will mean having to consume in the region of 2,250ml of fluid per hour in longer races to meet your sodium requirements, which is hard from a consumption and transportation point of view.'

However, you can replace lost electrolytes in various ways. As well as electrolyte drinks and electrolyte tablets for dissolving in water, salt capsules/sticks can also be taken directly.

Check out some of McGregor's favourite electrolyte products here.

'I usually suggest runners take in 700-900mg of sodium an hour during longer training runs and races,' she says. McGregor also suggests runners start drinking electrolytes in the 24 hours before race day.

Stomach issues

Runners often complain of being unable to stomach too many gels during a marathon, due to gastrointestinal distress or nausea. However, the idea that gels are to blame is a misconception, says McGregor. 'The biggest cause of mid-run stomach issues is related to sodium imbalance, not sports nutrition gels or bars. If you are dehydrated, and consuming glucose, it becomes highly concentrated in the gut. Blood is being directed away from the stomach to the working muscles, so the gut cannot absorb the glucose quickly enough, resulting in stomach upsets.'

What to eat before a marathon

preview for WHAT TO EAT BEFORE A MARATHON | Runner's World

In the three days leading up to your race, it's important to up your intake on carbohydrate to fill up your glycogen stores – this is often referred to as 'carb-loading'. The easiest way to do that it – without overloading your stomach which can cause you to feel bloated and sluggish – is by swapping elements of your usual diet for carbs. So, for example, if you usually have a piece of fruit or a yoghurt as your afternoon snack, swap it out for a couple of slices of toast or a hot cross bun.

For your pre-dinner meal, opt for meal which is high in carbs but low in fibre and fat, which may upset your stomach. For example, pasta with tomato sauce and garlic bread, or chicken/tofu/fish with potatoes/noodles/rice and a side salad. But don't overload yourself, as this can result in you feeling uncomfortable the next morning, due to the fact your stomach hasn't had time to digest all the food. One way around this is to have your main meal at lunchtime and then have a lighter meal in the evening, such as a sweet potato with soup and a little bread.

Make sure you experiment with different meal options prior to long runs, to see which suits you best – and stick to something tried and tested prior to your race.

On marathon morning, you'll likely be a little nervous but don't worry too much if you struggle to eat all of your breakfast. If you've already filled your glycogen stores in the days running up to your race, it won't make much difference.

Again, opt for something which is high in carbs but low in fat and fibre, such as porridge with a banana, nuts and honey or a white bagel with peanut butter and banana.

Opt for simple carbs – so white bread vs brown – which are lower in fibre, so are less likely to upset your stomach or leave you gassy. They also digest more quickly.

Experiment with different options in training to see what digests well and leaves you feeling full – but not heavy or bloated – and stick to your tired-and-tested breakfast on marathon morning.