Glycogen – The Practical Know-How – Part 2/2

Welcome to part 2/2 of our series on glycogen and its role among athletes. If you missed part 1, you can find it here. If you haven't read our foundational article on glycogen, you can find it here.

It's mainly the carbohydrate content in your diet that determines how much glycogen you store for fuel, so we must start here. For endurance athletes, the intake should be around 8-10 g of carbohydrates per kilogram of body weight per day over several weeks when your training volume is high. This represents anything from 60 percent of your total energy intake and upward. This should be compared to the population's average carbohydrate intake, which according to Riksmaten 2011, is at 44 percent of the total energy intake. Thus, an athlete needs to increase the percentage of carbohydrates in their diet. 

An aspect that should not be overlooked is the total energy intake, which is a significant determining factor for recovery. Consuming more than 10 g of carbohydrates per kilogram of body weight per day is not necessary for quick recovery from session to session as long as you achieve energy balance or a caloric surplus throughout the day.

“Consuming > 10 g carbohydrate/kg BW/day appears to be of no additional benefit to glycogen restoration. A major factor that influences the rate and extent of muscle glycogen repletion is total energy intake; even if adequate amounts of carbohydrates are ingested after exercise, glycogen repletion will not be complete unless sufficient energy (calorie) intake occurs”

Athletes who train intensively throughout the week, often with double sessions like morning swims and evening runs, are frequently working with partially depleted glycogen stores. But does this really matter?

The answer is: actually no. Researchers have shown that athletes with a moderate carbohydrate intake of 5 g/kg or a high intake of 10 g/kg over seven days could both sustain training capacity during cycling and running at 80 percent of maximum oxygen uptake (VO2max) across those seven days. This was despite the 5 g/kg group experiencing a 30 percent reduction in glycogen stores, while the 10 g/kg group maintained full stores.

Researchers concluded that a high carbohydrate intake reduces the risk of low glycogen stores, while moderate intake is enough to preserve training capacity over a week of intense training. A hypothesis explored by researcher Louis M Burke suggests that the body adapts to training with lower glycogen levels, delaying the onset of fatigue mechanisms as the muscles become more depleted. Thus, fluctuating glycogen levels may be beneficial, fostering adaptation each cycle.

In practical terms, this means you simply delay hitting the wall. 

However, Burke demonstrates, like many others, that if you further reduce carbohydrate intake to an "LCHF-level" of around 2 g/kg, performance suffers. Recently, a study was conducted on walkers who trained for three weeks on a low-carb diet, showing that their performance didn't improve in a 10 km walk. In fact, it declined by 1.6 percent, compared to the high-carb group who increased performance by 6.6 percent with an intake of 8.6 g carbohydrates/kg/day.

Many high-energy-consuming athletes (such as cyclists, triathletes, runners, skiers, orienteers) do not reach the level of 10g of carbohydrates/kg per day. This doesn't mean they can't perform, but rather that they aren't getting the full effect of their training sessions. When researchers have examined athletes' carbohydrate intake, it is 3-6 g/kg body weight in women and slightly higher in males. The gap between 6 grams and the lower recommended range of 8 grams doesn't necessarily mean that athletes can't train, but rather that recovery suffers and the athlete might not be able to perform quality workouts the very next day. If you want to delve deeper into recovery, we already have an article on Optimized Recovery that you should read. Perhaps also the article on Cherry.

To keep it straightforward, we suggest you maintain your regular eating habits, but generally replace some low-carb foods in each meal with a few extra carb-rich options. Additionally, include 1-2 snacks daily. Below, we've provided a carb-rich example for an athlete.

Meal, grams of carbohydrates: 

• Breakfast: 1 bowl of Muesli/Oatmeal with 1 sliced apple + cinnamon and 200ml of milk plus 1 cup of coffee – 45g
• Snack: 1 banana – 20g
• Lunch: Pasta Pesto with Mushrooms – 55g
• Snack: Dried Fruit 2 handfuls – 65g
• Dinner: Lasagna + 1 glass of milk – 60g
• Evening snack: 2 sandwiches with your choice of topping – 30g

= Total – 275g and 2000 kcal

If you currently weigh 75 kg, this means 3.7 g of carbohydrates per kilo of body weight. However, this is way too little energy as it's calculated according to the Swedish National Food Agency's normal portions. If we increase the intake by 50 percent and reach 3000 kcal, you'll be at a sufficient energy level on a rest day or days with light training. Here, you'll get 5.7 g of carbohydrates/kg of body weight, and the meals are as follows (slightly adjusted since no one eats, for example, 1.5 bananas):

Meal, grams of carbohydrates: 

• Breakfast: 1.5 bowls of Muesli/Porridge with 1 sliced apple + cinnamon and 3 dl milk, plus 1 cup of coffee – 65 g
• Snack: 2 bananas – 45 g
• Lunch: Large portion of Pesto Pasta with Mushrooms – 80 g
• Snack: Dried Fruit 3 handfuls – 100 g
• Dinner: Large portion of Lasagna + 1.5 glasses of milk – 90 g
• Evening snack: 3 sandwiches with optional toppings – 45 g

= Total – 425 g (+55%) and 3000 kcal

We've chosen carbohydrate-rich foods and dishes in the diet plan above, but as you can see, it still requires some planning and a couple of snacks to reach the level of 10 g/kg. It's more than many imagine, which you'll notice when you start eating, especially if you still want to include vegetables and other calorie- and carbohydrate-light and filling items in your meals.