Why are carbohydrates important?

Bowl of oats on a blue tartan background.

Oats are a great source of slow release carbs

One word: fuel. Carbs are the preferred energy source for your muscles, brain and central nervous system.

Without carbohydrate, you’ll ‘hit the wall’. Run out of carbs and your body will turn to fat and protein for fuel, and while eating into your body’s fat stores might seem like a good idea, you definitely don’t want to lose any of your lean muscle mass.

Grains, fruit, milk products and to a lesser extent, vegetables are sources of carbohydrate. And of course there’s sugar – but more about that later.

The carbs in your diet are broken down into fructose, glucose and galactose – smaller units of sugar that are absorbed through your small intestine into your bloodstream. Fructose and galactose are taken to the liver to be converted to glucose. The glucose goes to where it’s needed for energy: your brain, organs and your muscles.

Any glucose your body doesn’t burn straight away is stored in your muscles as glycogen. Once your glycogen stores are full, any remaining glucose is stored as fat.

Fuel supply

As an athlete, keeping your carbohydrate levels topped up is vital for maintaining performance right the way through your workout. Typically your muscles are able to store enough glycogen for around 90 minutes of steady activity or 20 minutes of high intensity work. That’s why it’s very important for athletes to regulate their carbohydrate levels before, during and after exercise. And to do that, you need to pay attention to the types of carbs you consume and when you consume them.

Glycaemic index

All carbohydrate rich foods are given a GI number. This figure represents the degree of blood sugar increase experienced after consuming a particular food. The higher the number, the faster the glucose is released into your blood, the lower that figure, the slower the release of sugars.

Simple Carbohydrates

Quick release glucose sources are called simple carbohydrates. Here we’re talking refined sugar, honey, some fruits and highly processed grain products like white flour. After consuming simple carbs, you get a quick burst of energy which if not used immediately, causes a corresponding insulin spike, as your body seeks to regulate itself. That’s bad news if you glug down too much energy drink too long before the start of your training session because after the sugar rush, you’ll get the crash – hardly good preparation for a great performance. However, if you’re well into your race and need ready fuel to maintain optimal performance, simple carbs are an idea fuel source because they’re easily digested and ready to go to work.

Medium GI Carbohydrates

Medium GI carbs are great post exercise. While it may be hard to eat right after a gruelling session at the gym, some milk, fruit juice or perhaps a smoothie within 30 mins of exercise optimises the replacement of spent glycogen.

Slow Release Carbohydrates

Slow release carbohydrate rich foods like oats, and whole grain products produce a steady release of carbohydrate into the blood. They’re perfect for fuelling up for the slow burn, so ideal for your general diet and for carb loading before training or the big race.

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