Endurance athlete? This is how to prevent an energy dip during your competition

Are you a recreational runner, cyclist or triathlete who has experienced an energy dip during a long training session or race? Then carbohydrate loading (also known as ‘carb loading’) can help you prevent this. This nutritional strategy, combined with taking it easy in the week leading up to your important race, can ensure you finish much stronger.

As an experienced (ultra)marathon runner, I can confirm from my own experience that tapering and carb-loading really work. I was in my thirties when I was very enthusiastic about running and a member of a running club for (ultra)marathon runners. In those same years, I started working as a part-time sports nutrition coach. In total, I ran 12 full marathons, 2 ultramarathons of 50km, and countless half marathons. After my first few marathons, I started using this strategy for all subsequent marathons and ultramarathons. The difference in how you feel during those final kilometres is enormous.

Why does this work so well?

Your body stores carbohydrates as fuel in your muscles and liver. This supply is limited, however: about enough for 90 minutes of hard cycling or running. If you exercise for longer and this ’tank’ runs empty, you'll suddenly feel very tired and heavy. Many athletes will recognise this feeling: the notorious ‘man with the hammer’.

By deliberately eating plenty of carbohydrates in the days leading up to your race, you can increase your energy reserves by 20 to 40 per cent. It’s just like getting a bigger fuel tank! From my own marathon experience, I can say that this difference really becomes noticeable after the 30-kilometre mark, where many runners encounter the infamous ‘hitting the wall’.

When I ran my first marathons, I also hit the wall, and it was a matter of survival until the finish line. However, when I started tapering and carb-loading for subsequent marathons, things improved significantly. I achieved personal bests in all the marathons that followed, partly thanks to this smarter nutrition strategy.

Research shows that this is particularly beneficial during exercise lasting longer than 90 minutes, where carb-loading can improve performance by 2–31% (https://pmc.ncbi.nlm.nih.gov/articles/PMC9734239/. For the shorter distances I ran (10km, 15km) I noticed myself that simply eating well the day before was sufficient.

It also helps to ease up on your training in the final week before your competition. We call this ’tapering’. This gives your body the chance to rest properly and store that extra fuel.

How do you approach this practically?

Carbohydrate loading has a clear structure that you can follow step by step. Recent research from Sports Medicine (2022) confirms that carbohydrate loading over 2-4 days can effectively improve performance in endurance activities lasting longer than 90 minutes.https://link.springer.com/article/10.1007/s40279-022-01757-1Although scientific research shows that 8-10 grams of carbohydrates per kilogram of body weight works from the start, I personally prefer a gradual increase. This way, you don't make a large jump all at once but build up gradually, which has proven effective in practice. This applies to myself as well as to other recreational and amateur runners I have coached.

5-7 days before your matchStart tapering gently: gradually reduce your training intensity and duration. Continue to eat as usual.

3-4 days before your matchNow the carbohydrate loading begins! Start with 6-8 grams of carbohydrates per kilo of body weight per day. For a person weighing 70 kilos, that means 420-560 grams of carbohydrates. Only do light training sessions of a maximum of 30-45 minutes.

1-2 days before your matchIncrease to the maximum stacking of 8-10 grams of carbohydrates per kilogram of body weight per day. For a person weighing 70 kilos, this means 560-700 grams of carbohydrates. Spread this over multiple meals, such as 5 or more. Rest completely or do a maximum of a very light jog of 20-30 minutes to keep the legs loose.

On match dayEat a carbohydrate-rich meal 2-4 hours before the start. During matches longer than 1.5 hours, you can take an extra 30-60 grams of carbohydrates every hour. For very long matches (from 3 hours onwards), you can even take up to 90 grams per hour by combining different types of carbohydrates: 60 grams of glucose + 30 grams of fructose.

What should you eat and what should you pay attention to?

For this strategy, the best carbohydrate sources are simple foods that won't upset your stomach: white rice, pasta, potatoes, white bread, porridge, and bananas. On normal days, you can perfectly well eat complex carbohydrates. Think wholemeal bread, brown rice, or wholemeal pasta. However, I advise consciously choosing ‘white’ products during the carb-loading days (3-4 days before the competition) and especially on the competition day itself, as they contain fewer fibres and are therefore easier to digest.

Important tips from practice:

• Make sure you drink plenty of water! For every gram of glycogen stored, your body retains 3–4 grams of water. This means you need to increase your water intake by about 50% during the loading days (3–4 days before the race). This can cause you to gain 1–3 kilos, but that’s perfectly normal. In my experience, this weight disappears during the competition because you sweat it out.
• Always test this approach first during training or a less important race. This will prevent unpleasant surprises. I learned this the hard way during my third marathon! (bowel problems, hit the wall)
• Listen to your body. Do you feel nauseous or heavy? Then eat a bit less or choose different products. After 12 marathons, I know that white rice and bananas work best for me.

Carbohydrate loading isn't magic, but it is a proven way to increase your energy stores. For recreational athletes, it can make the difference between trudging over the finish line exhausted or finishing with a smile. From my experience with marathons and ultramarathons, I can say: give it a try. You'll be amazed by the difference!