Carbohydrate loading: when and how to do it? Is it really necessary?

As a race or major endurance goal approaches, many endurance athletes turn to a well-known nutritional strategy: carbohydrate reload (or "carb loading"). It promises to increase energy reserves and delay fatigue, but is it really necessary for every race? Who is it for, and more importantly, how can it be applied effectively without risking the opposite effect?

In this article, we take stock of what the science says, the mistakes to avoid, and the best practices to maximize your performance on the big day.

1) Why replenish your glycogen reserves?

Le glycogen is the form in which the body stores carbohydrates, mainly in the muscles and liver. During prolonged endurance exercise, it is the preferred energy sourceThe problem is that these reserves are editions.

On average, an athlete can store:

• Around 400 to 500 g of muscle glycogen, or 1600 to 2000 kcal,
  

• Et 80 to 100 g of liver glycogen, or 300 to 400 kcal.
  

At moderate to high intensity, these reserves can be depleted in 1h30 to 2hThis is precisely where carbohydrate loading comes in: it allows these stocks to be increased to the maximum, to last longer at high intensity.

2) What the studies say

The research is clear: for prolonged endurance efforts, la carbohydrate loading improves performance. A meta-analysis by Burke et al. (2011) showed a average gain of 2 to 3% during events exceeding 90 minutes.

Other classic studies confirm this benefit:

• Karlsson & Saltin (1971) observed a significant improvement in marathon performance,
  

• Sherman et al. (1981) showed prolonged time to exhaustion in cyclists following a carbohydrate loading protocol,
  

• Jeukendrup et al. (2000) demonstrated better power conservation at the end of long-distance triathlon.
  
  

But beware : below 90 minutes of effort, the profits become almost zero, or even counterproductive (temporary weight gain, digestive discomfort, etc.).

3) When should it be implemented?

La carbohydrate reload is not a universal strategy. It must be used wisely, depending on the objective and duration of the effort.

It is useful for:

• Events lasting more than 90 minutes : marathon, trail, triathlon, cyclo-sport…
  

• Sequence of long sessions (training, ultra, back-to-back).
  

• Target optimal performance at high intensity.
  
  

It is useless, or even not recommended for:

• Short tests (< 1h15).
  

• Classic training outings.
  

• Periods of weight loss or strict management of calorie intake.
  
  

4) How to recharge efficiently? The modern protocol

The old methods relied on a carbohydrate depletion followed by “refeeding”. Too restrictive, they were largely abandoned.

Today, the most effective and best tolerated protocol is based on:

• There’s nothing quite like a increase in carbohydrate intake for 1 to 3 days before the test,
  

• Without depletion phase,
  

• Associated with a gradual reduction in training volume.
  

Generally, the recommendations suggest 8 to 12 g of carbohydrates per kg of body weight per day.

Example: for a 60 kg athlete → 480 to 720 g of carbohydrates per day.

This may seem like a lot... and it is! Hence the importance of favoring easily digestible foods with a moderate to high glycemic index, while limiting fiber, fats, and proteins.

5) What foods should you favor?

Here are some ideal sources to achieve this goal:

complex carbohydrates such as white pasta, basmati rice, semolina, potatoes
simple carbohydrates : compotes, ripe fruits like bananas, fruit juices, energy bars, carbohydrate drinks, maltodextrin powder (easy to digest and measure)

However, avoid legumes, raw or high-fiber vegetables, fatty or high-protein products because they slow down digestion, and foods that are unknown or have not been tested during training.

If you tolerate it, you can keep a small portion of cooked vegetables.

And don't forget: the glycogen is stored with water (approximately 3g of water for 1g of carbohydrates). Hydration must therefore be increased (approximately 30 to 40 ml/kg/day), without excess.

5) Common mistakes

1. Eating too much at once : it is better to spread carbohydrates throughout the day.
   

2. Forgetting to test the protocol in training : it’s risky on D-day.
   

3. Incorrectly measuring the quantities : underdosing is not effective, overdosing can cause digestive problems.
   

4. Ignoring digestive signals : You should not force yourself to the point of creating nausea or disgust.
   
   

In short

The final word

La carbohydrate reload is not a myth: it's a solid, scientifically validated strategy for improving prolonged endurance performance. You just need to know when and how to use it. When well planned, tested in advance, and adapted to your specific needs, it can help you reach a new level... and perhaps avoid the dreaded "wall" during your next race.