How to prepare for a marathon: The 10 best carbohydrates for runners

While I normally try to limit my everyday carb intake, I secretly look forward to that bowl of spaghetti bolognaise or pad thai I'll inevitably scoff in the lead up to a race.

After all, carbohydrates play an important role in maintaining a healthy diet and are a key fuel source for runners, especially during long or high intensity runs.

But which carbs should you be reaching for?

High-low ratios

Renae Eastlake is a dietician and keen long distance runner from Wollongong. She says not all carbs are created equal, advising runners to choose the right variety and eat it at the right time to get the most benefit.

"Carbs are a primary source of energy and help to both fuel a run and replenish energy once you've crossed the finish line. They can be eaten before, during and after exercise," says Eastlake.  

"Once digested, carbohydrates are broken down to sugars and released into the bloodstream where they are carried around the body to our cells and stored as glycogen, acting as the primary fuel source for exercising muscles. If carbohydrates are not present, your body will utilise fat and protein for energy which is an inefficient energy source for runners."

Eastlake says there are two types of carbohydrates – simple and complex – and runners can use both to fuel their run.

Simple or High Glycaemic Index (GI) carbohydrates

Eastlake says simple carbohydrates are broken down into sugar quickly. "All simple carbohydrates are made of just one or two sugar molecules. They are the quickest source of energy, as they are very rapidly digested. However, the energy can be short-lived, requiring another meal or snack to keep things going."

Bananas

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Bananas are a fast acting pre or post-race food. They have a moderate to high GI and are easy to digest. Loaded with potassium, they also help to quickly replace electrolytes lost on a run.  Eastlake recommends eating one at least an hour before a run or with plain yogurt when you get home.

White toast

Your race day breakfast should be low in fat and fibre to help prevent gastrointestinal distress like the runners trots. Eastlake says white toast with jam or honey is a great pre-run breakfast carbohydrate and can be eaten as a snack a couple of hours before a run to provide an energy boost.

Pasta

This well-known carbohydrate dense food provides runners with around 35g of carbs per cup of pasta. Serve it with lean protein such as chicken and some vegetables to increase the nutritional value.

Dried fruit

If you're going on a long run of more than 90 minutes Eastlake suggests packing a small handful of raisins, dried apple or dates to snack on as an alternative to sports drinks or gels. "Dried fruits are a great on-the-run fuel because once eaten they are quickly absorbed and can help replenish the glycogen stores you're depleting on a long run," she says.

Chocolate milk

For a super-charged energy hit after a long run reach for a bottle of chocolate milk. "While not a food you immediately think of as a carbohydrate, chocolate milk is low GI and will help you re-fuel and quickly get sugar back into the muscles after a workout," says Eastlake.

Complex or low GI carbohydrates

Complex carbohydrates are slow releasing, taking longer to be absorbed by the body and provide sustained energy during exercise. Eastlake says whole fruits and vegetables, dairy, whole grains, sweet potatoes and legumes are the best sources of low GI carbohydrates. "These foods come with the added benefit of nutrients and vitamins including calcium, fibre and iron and help runners feel fuller for longer."  

Brown rice or quinoa

Whole grains such as brown rice and quinoa are among the highest sources of carbohydrate. "These slow releasing carbohydrates are healthier than white rice or pasta because they include fibre and vitamins and minerals. Half a cup of cooked brown basmati rice provides 25g of carbohydrates and the ancient grain quinoa is a good source of protein," says Eastlake.

Yoghurt

All dairy is typically low GI and the combination of carbohydrates and protein found in plain yoghurt makes it an excellent post-run recovery snack.  But stay clear of flavoured yoghurts as they are unnecessarily high in sugar.

Sweet potato and beetroot

Sweet potato is a dense carbohydrate and a great pre-run vegetable. Unlike pasta or rice, it's loaded with vitamins and minerals such as vitamin C, E and beta-carotene, which help to build a healthy immune system to combat the stress running places on your body. Beetroot is also packed with vitamin C as well as magnesium. Eastlake says that it's even been linked to "increased performance and speed in runners by improving blood and oxygen flow to the muscles."

Stocking up the right way

A common myth about running is the carb-load done before a big race. But it's enough just to gorge (although it can be a lot more fun). A smart runner is strategic with their energy intake.

Eating high carbohydrate foods leading up to a race stocks your muscles and liver with glycogen. But it's only necessary if you're exercising intensely and continuously for 90 minutes or more.

Eastlake says that to avoid having an upset stomach or feeling sluggish on race day don't pile up pasta the night before a big run. Instead, slowly increase your carbohydrate intake in the two to three days before your race. This will top up your reserves without feeling like a dead weight is sitting inside your tummy.

The goal of one day completing an ultra-marathon inspires running fanatic Laura Hill to clock up the kilometres each week. With a day job in the corporate world, Laura loves nothing more than lacing up her runners and hitting the pavement to clear her mind and challenge her body.

Follow Laura Hill on Twitter

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