How to Fuel a Marathon

How to Fuel a Marathon

Whether you are training for a marathon or any other endurance event this season, you’ll need to have a well-rehearsed fuelling and hydration plan if you want to perform to your best ability and avoid nutrition mishaps.

The most common nutrition challenges you’ll face when training for a marathon include dehydration, overhydration, running out of energy, overheating, cramping and gut problems. With this in mind, here are some simple tips to help you avoid these common nutrition pitfalls.

Fuelling training runs

Training runs can be useful for practicing your race nutrition. Trial different foods and drinks, amounts and timings during training to pinpoint what works for you (and what doesn’t).  Doing this will help avoid gut problems on race day.

Carbohydrates deliver energy to muscles faster than fats but are stored in much smaller amounts – about 500g, not enough to fuel 26.2 miles – so you’ll need to top up blood glucose with carbs at regular intervals during long runs.

Many runners prefer doing their long runs early in the morning, especially at the weekend. If this is you, then prioritise carbs in your meals the day before to ensure you have plenty of glycogen in your muscles. Its fine to skip breakfast if you want, but have a small pre-run snack 15- 30 minutes before you set off – good options include a banana, a slice of toast or a bagel with honey or peanut butter.

If you find it hard to eat solid food before your run, try a sports drink, diluted fruit juice or a smoothie – this will ensure hydration as well as carbs to maintain blood glucose levels. 

Practice makes perfect

Aim to do two or three long runs using the same fuelling schedule you plan to use in the race. Simulate race-day conditions as far as possible, using the same foods and drinks and practise taking them at the frequency you anticipate during the race. Making it as realistic as possible will help ensure there won’t be any surprises on race day.

You’ll also need to practise drinking on the move from cups or bottles. This may feel tricky or uncomfortable if you’re not used to it so start with small amounts and gradually build up. Check in advance what’s available on the course and where the water stations will be so you can practice with the same products (if you want to) and plan where to refuel.

Whichever carbs and drinks you choose, start fuelling 45 – 60 minutes into your run. Aim for 30g carbs / hour if you’re anticipating a finish time > 4 hours; 60g/ h for a < 4-hour finish time or 90g/ h for a < 3 hour finish time. Good options that serve up 30g of carbs include one large banana, 500ml of an isotonic sports drink, one fruit + nut bar, or two Medjool dates.

2 – 3 days before the race

In order to start the race with a full tank of fuel, you’ll need to increase high-carb foods in the days before the race. This is called ‘carb-loading’ and can be achieved by a training taper for 2 – 3 weeks leading up to the race together with an increase in carbohydrate intake for the final 2 - 3 days. Good sources of carbs include oats, rice, potatoes, sweet potatoes and pasta. Fat and protein should be reduced to allow for an increase in carbs.

However, carb-loading doesn’t mean eating as much as possible. If you over-load, then you risk feeling bloated and lethargic on race day. If you are prone to gut problems, then you may wish to limit your intake of fibre during the 48 hours before the race.

The day before the race

Make your last big meal at lunchtime, not late in the evening, then a smaller meal at least 2 -3 before bedtime. This will ensure enough time to digest your food, so you won’t feel bloated on the morning of the race. Good options include a simple pasta dish, rice with chicken or beans or jacket potato with hummus or tuna. Avoid any new or untried foods or food combinations in case they upset your stomach.

The morning of the race

Aim to have your pre-race meal 2 – 4 hours before the event. The aim is to top-up carbs to ensure your liver glycogen stores are full before the start. Porridge or overnight oats with bananas, granola with fruit, or toast with jam are all great options. Stick to what you normally eat before a long run, nothing new. Drink plenty of fluid to ensure you are hydrated (your urine should be pale yellow), then sip as needed.

15 – 30 minutes before the start

If you skipped your pre-race breakfast or feel hungry, then consuming carbs shortly before the start will provide energy for the first part of the race. However, this is not essential. Aim for 20 – 30 g carbs with water - this could be a banana, sports drink or bar.

During the race

Replicate the strategy you have built during your training runs. However, be prepared to adapt if conditions change. For example, if it is hotter than expected, you’ll need to drink more; if gut problems arise, then you may need to cut back on carbs. Remember, don’t try any new products on race day in case they don’t agree with you.

After the race

Ensure you rehydrate over the next few hours by drinking water or sports drinks. Eat plenty of carbs and protein to aid muscle recovery – plus some fruit or veg for their antioxidant benefits. Once you’ve done that then, provided you’re not planning on running another marathon the next day you’re free to eat whatever you fancy!


Author: Anita Bean

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