I like to think of glycogen stores as your pantry: if it’s looking bare, it’s time to go to the store and top up. After all, glycogen provides much of the carbohydrate you use to fuel endurance exercise. 

For context, around 90-120 minutes of intense exercise will generally deplete your glycogen stores enough to significantly impact your performance. So, there’s rightly plenty of focus on how much carbohydrate you need per hour during exercise to ensure you continue to perform at your best. 

But, no matter how much you consume during an activity, you’re bound to finish longer sessions and races somewhat depleted. So, it’s also worth considering how you can optimise your carb intake after exercise to ensure you’re refueling properly before heading into your next session… 

How much carb do you need to optimise recovery?

According to the ISSN, athletes training to improve their performance need to consume 5-8g of carbohydrate per kg of bodyweight each day just to maintain glycogen stores (compared with the 3-5g per kg recommended for active individuals who are not training in a focused manner).

It can go up to 10g/kg if you’re training at a high intensity for longer periods - which is defined as “3-6 hours per day of intense training over 1-2 daily workouts for 5-6 days per week”.

But we don’t just want to maintain – we want to MAXIMISE since glycogen stores are depleted by high volume exercise. So, the recommendation becomes 8-12g/kg daily at times when you’re really putting the work in as a hard-charging endurance athlete.

When honing in on the best approach to post-exercise carb intake, you should aim for 1.2 g/kg each hour for the first 4 hours after the workout. Then, you can focus on your daily carbohydrate totals (i.e. ~8g/kg). 

The reasoning for being strategic with your carb intake straight after exercise is because the body is primed to take up glucose in this timeframe. GLUT4 receptors have translocated to the membrane during exercise and will go back “home” after 30-60 minutes. Absorption is faster at first and then slows down as more time passes. 

During those first four hours, a standard rule of thumb to follow would be a 4:1 ratio of carbs to protein.

A proactive carb intake

Quick turnaround times (within the next 12 hours) between training sessions and races necessitates fine-tuned strategies. If the timeline between sessions is four hours or less, you will need rapid restoration through carbohydrate because it takes ~4 hours to fully digest and assimilate into glycogen.

It’s still worth focusing on replenishing your stores, even if your next session is less endurance focused (e.g. weight lifting) because this can deplete intramuscular stores and affect performance. 

Other situations where a proactive approach to recovery is necessary include where you’ve gone into a session fasted, you’re in a weight loss phase, or you’ve found that you’re continually slacking on carbohydrate intake. Needless to say, if your situation ticks off a few of those boxes, find the nearest carb and chow down.

For those stricter scenarios, our carbohydrate consumption goals become tasks. So yes, that third bowl of cereal is not a want but a need.

Image Credit: Finlay Woods ©

Improving speed of carb absorption

You may want to look at the type of carbohydrate you’re choosing to replenish your stores. Combining glucose and fructose can be beneficial, as their absorption pathways are different. The transporters responsible for glucose uptake appear to max out around 60g/h. However, fructose uses a different route that’s independent of the glucose transporters. Those receptors typically have a cap around 30g/h. Combining the two can increase the total amount you can absorb per hour. 

A general guideline for the ratio is 2:1, as long as your digestive system is tolerating it well. The joint effect may help promote a greater rate of carbohydrate oxidation during exercise, too. Glucose and sucrose or maltodextrin and fructose would be winning duos. Practically, a glucose and fructose source could be as simple as table sugar – otherwise known as “sucrose”, which is 50/50 glucose and fructose.

But wait – there’s more! And by more I mean more carbs to absorb. More recent research is showing that the 90g/h cap is not a hard cutoff, so training your gut and letting your body adapt to a higher intake over time could push that ceiling upward.

Glycemic index

The glycemic index (GI) is a touchy subject with a mixture of outcomes when it’s actually put into practice, as the GI number of a food is affected based on the serving size and what other foods are eaten with it. 

However, opting for higher glycemic index (>70) sources for those first four hours can be an extra step that may be helpful for an aggressive glycogen repletion strategy. It’s basically the opposite of typical health-promoting advice because you’re decreasing your sources of fibrous, slow digesting carbohydrates, which gradually release into your bloodstream in order to avoid spiking your blood sugar.

In an athlete’s case, a blood sugar spike can be good because it causes an insulin spike. Insulin is responsible for telling your body to take the glucose in your blood and put it away for storage as glycogen. 

Protein, caffeine and creatine…

Speaking of insulin, protein can also spike insulin, meaning this macronutrient (especially whey protein) can be a helpful coingestion with carbohydrates. Use the 4:1 ratio mentioned earlier (e.g. 60g carb + 15g protein).

Some athletes also add caffeine (3-8 mg/kg) and even creatine, although the literature is mixed on creatine’s effect on muscle glycogen storage (ranging from helpful to neutral).

It’s also beneficial to ensure you’re getting enough B vitamins in your diet, as they help transition glucose into adenosine triphosphate (ATP) to make energy. Improving your physical fitness overall can help too, as this is a stimulus for enhancing muscle glycogen stores

While we know that muscle protein synthesis rates decline with age, it’s unclear if that same concept applies to glycogenesis. It may mean that more years under your belt means you’re more experienced and thus more aware of the benefits of properly replenishing carbohydrates.

Finally, the best way to help absorption is to just eat enough and to make sure you’re not overloading your stomach before you get to the carbohydrate intake you need. 

Image Credit: Finlay Woods ©

Example menu to optimise carb intake

Let’s take the average daily goal of 8g/kg to optimise glycogen stores. For a 65kg athlete, this comes out to 520g of carbohydrate per day

Here’s a sample full day of eating, using an average metabolic rate and energy expenditure activity multiplier to find a total calorie target (this would vary based on the individual). Other factors to consider that could further fine tune these numbers and food sources are dieting history, weight goals, gut tolerance, food preference, allergies, health conditions, specific sport, training level, schedule, budget.

65 kg athlete

  • Goal: ~2900 kcal
  • 520g carb
  • 104g protein (1.6g/kg min)
  • 45g fat (remainder)
Breakfast Calories Carbs Fat Protein
6 oz Greek yoghourt 100 7 0 18
1 cup granola 234 41 6 6
1 large banana 121 31 0 1
2 TB honey 128 35 0 0
Pre-training Calories Carbs Fat Protein
1 packet fruit snacks 80 19 0 1
Post-training Calories Carbs Fat Protein
1 large scoop whey protein 110 3 1 22
9 pieces dried mango 360 90 0 6
Lunch Calories Carbs Fat Protein
2 cups penne 400 84 2 14
1 cup marinara 140 30 2 4
2 slices French bread 348 66 3 14
Snack Calories Carbs Fat Protein
2 pouches blueberry muffin bites 360 50 16 4
Dinner Calories Carbs Fat Protein
1 chicken thigh 173 0 11 17
1 large sweet potato 245 38 10 3
1 cup eggplant 21 5 0 1
1 ear of corn 100 21 1 3
Daily totals: Calories Carbs Fat Protein
2920 520 52 114

Key takeaways

  • Aim for 5-8g of carbohydrate per kg of bodyweight each day to maintain glycogen stores
  • If training at a high intensity for longer periods, aim for 8-12g/kg daily
  • For the first 4 hours after exercise, aim for 1.2g/kg each hour
  • And then return your focus to your daily carbohydrate totals

Energy density

The guidelines we've talked about might seem like a lot of food and one of the key steps is mastering the art of 'food volume'. For instance, breakfast cereals are an energy dense food, meaning that there's a lot of grams of carb packed in per gram of cereal.

We can use tricks on our brains to make it feel like we’re consuming more or less calories simply by changing the energy density of foods we consume. For instance, pineapple and mango are more dense than blueberries and strawberries. Sure, the latter two provide a nice dose of fibre – making them “healthy” to most people — but that may not be the criteria we need for this specific glycogen replenishment goal.

Food volume is a great tool for eating more without feeling bloated. If you need a lot of carbs, seek out high energy dense foods instead of high volume foods. Pasta and cereal are two great sources for this tactic.

Other tips for eating more:

  • Drink your carbs (liquid calories are usually easier to add in than more food, so try the Carb Only Drink Mix
  • Keep fat intake on the lower end (fat might fill you up faster and crowd out the carbs you need)
  • Limit high fibre foods (these can also make you feel fuller)
  • Eat frequently
  • Have a snack before bed
  • Eat foods you ENJOY! Incorporate some treats (poptarts, fruit snacks, cupcakes may not be a bad thing in this case)
  • Add condiments like honey, jam, syrup (you’d be surprised by the carb content per serving)
  • Keep carb snacks in your car, gym bag, purse, backpack, desk
  • Buy and prepare meals in bulk (rice cookers are a great invention)
  • Train your gut to tolerate larger amounts of food

Ultimately, make sure your pantry is fully stocked!

Further reading