Glycogen Replenishment After Exercise: What a 2025 Cycling Study Reveals About Carbs, Recovery, and Timing

If you’ve ever wondered how much carbohydrate you really need after a hard ride – and whether it should go to your muscles, your liver, or both – this study gives you a lot to think about.In this post, we break down a 2025 paper from Dr. Cas Fuchs and colleagues on glycogen replenishment after exercise, including why they used well-trained cyclists, what 10 grams per kilo of body mass actually looks like, and why liver glycogen can recover much faster than muscle glycogen. If you work with endurance athletes, race back-to-back days, or just want to understand post-exercise fueling better, this one is worth your time.

What is glycogen replenishment, and why does it matter?

When you eat carbohydrates, your body can use them right away for energy or store them as glycogen. Glycogen is the storage form of carbohydrate, and it lives mainly in two places that matter for performance:

• Muscle
• Liver

That distinction is important. Muscle glycogen fuels the working muscles directly during exercise. Liver glycogen helps keep blood glucose stable, which matters for your brain, your nervous system, and overall endurance.Dr. Fuchs explained it simply: you can store carbohydrate almost everywhere in the body, but for exercise performance, the big players are the liver and the muscle. That’s why recovery nutrition is not just about “eating carbs” in a vague sense. It’s about restoring the right fuel in the right tissues at the right time.For endurance athletes, especially cyclists doing stage races or repeated training days, that timing matters a lot. If you don’t replenish glycogen well, the next session can feel harder, power output can drop, and recovery can drag.

How much glycogen can you store?

A rough estimate is:

• Muscle glycogen: about 350 to 700 grams total
• Liver glycogen: about 100 grams on average

Those numbers vary based on body size, muscle mass, training status, and diet. Endurance athletes often store more glycogen than sedentary people, and athletes with more muscle mass usually have more storage capacity too.That said, the body doesn’t always use or replenish these stores in the same way. This study is interesting because it helps separate what happens in the liver from what happens in the muscle.

Why the researchers studied cyclists and used 10 g/kg of carbohydrate

This study was designed around a practical performance problem:

How fast can you restore glycogen after a hard ride when recovery time is limited?

That question matters in real-world sports like:

• Stage racing
• Multi-day cycling events
• Tour-style race blocks
• Back-to-back hard training days

The researchers also wanted to study the liver more directly. Muscle glycogen has been studied for decades using muscle biopsy, but the liver is harder to measure in humans. In this project, they used MRI and spectroscopy techniques to help quantify both tissue size and glycogen content.

The study design

The study used a crossover design with 12 well-trained male cyclists. Each cyclist completed two conditions:

1. No-carbohydrate recovery
2. High-carbohydrate recovery

Before the recovery period, the athletes did a long, exhaustive cycling bout – about two hours – intended to reduce glycogen stores as much as possible. The participants were fasted, and the testing day was long because scanning and biopsy procedures took time.That matters because the recovery window wasn’t perfectly immediate. In the carbohydrate condition, the cyclists began receiving carbs about 2 to 2.5 hours after exercise, not instantly at the finish line.That’s an important nuance. A lot of athletes assume “post-workout” means immediately after the session ends. In reality, there are often delays, especially in research settings or during competition logistics.

What they were given

In the high-carb condition, the cyclists consumed 10 grams of carbohydrate per kilogram of body mass over 12 hours. For a 150-pound person, that’s roughly 680 grams of carbohydrate. That intake was delivered in two phases:

• First 6 hours: sucrose drink every 30 minutes
• Second 6 hours: two carbohydrate-rich meals

Why sucrose? Because sucrose is 50% glucose and 50% fructose. That combination appears to be especially useful for liver glycogen restoration.

What the study found: liver glycogen rebounds faster than muscle glycogen

The findings were very clear.

In the no-carb condition: As expected, exercise lowered both liver and muscle glycogen. During the 12-hour recovery period with no food, glycogen stayed low. No surprise there – if you don’t replace carbohydrate, you don’t restore carbohydrate.

In the high-carb conditionThe liver and muscle behaved very differently.

Liver glycogen

By 6 hours, liver glycogen was already restored – and in some measurements, it was even higher than pre-exercise levels. That’s a fast turnaround.

Muscle glycogen

Muscle glycogen did improve, but not nearly as quickly. Even after 12 hours of high carbohydrate intake, muscle glycogen was only about 70% of pre-value

.So the main takeaway is this:

• Liver glycogen can recover quickly
• Muscle glycogen takes longer
• 12 hours is enough for liver recovery, but not full muscle recovery

This is a big deal for athletes who think all carbohydrate goes equally to all storage sites. It doesn’t.

Why that matters in practice

If you’re racing or training again soon, you may be able to restore liver glycogen fairly quickly, especially with high carbohydrate intake. But muscle glycogen is harder to fully refill in a short window.That means the muscle may still be under-fueled even when the athlete feels “recovered” on paper.For coaches and athletes, this is one reason post-stage fueling is so important. You’re not just trying to survive the night. You’re trying to set up the next day.

Why sucrose helped, and what that means for real-world fueling

One of the most interesting parts of the discussion was the carbohydrate type. Dr. Fuchs explained that in previous work, sucrose appeared especially effective for liver glycogen restoration compared with glucose alone. That’s likely because fructose is handled differently in the body and seems to support liver glycogen replenishment well.

Why glucose and fructose together can help

The intestine has different transport systems for glucose and fructose. That means when you combine them, you can often absorb and handle more carbohydrate than if you rely on glucose alone.This matters for two reasons:

• It can improve tolerance
• It can increase the amount of carbohydrate delivered to the body

That doesn’t automatically mean “more is always better,” but it helps explain why many endurance fueling strategies now use mixed carbohydrate sources.In this study, the researchers used sucrose drinks first because they wanted a carbohydrate that would strongly support liver glycogen recovery. Later, they switched to more practical meal-based feeding.That’s a useful reminder: research protocols are often designed to answer a precise physiological question, not to mimic everyday eating exactly.

What about fructose and muscle glycogen?

This is where the nuance matters.Based on prior work, changing the ratio of glucose to fructose may not make a huge difference for muscle glycogen recovery. Muscle seems less sensitive to that ratio than the liver does. So if the goal is muscle recovery, the total carbohydrate dose and total time available may matter more than the exact sugar mix.If the goal is liver recovery, the fructose-containing carb source may be more valuable.

What this means for athletes, coaches, and everyday exercisers

The study is especially relevant for athletes who need to recover fast between demanding sessions.

1. If you have less than a day, prioritize total carbohydrate intake. The data suggest that muscle glycogen usually needs around 24 hours to fully recover after a hard, depleting session in well-trained cyclists.So if your turnaround is short, the goal isn’t perfection. The goal is to get as much carbohydrate in as you can, as early as you can, and keep feeding consistently.

2. Don’t ignore sleep. Dr. Fuchs emphasized that sleep matters not just for general recovery, but potentially for glycogen restoration too.If you’re trying to recover for tomorrow, a good sleep window is part of the recovery strategy. You can’t just out-eat bad sleep.

3. Use multiple feeding opportunities. For elite cyclists, the most realistic strategy is usually not one giant meal. It’s a sequence of intake moments:

• Drink carbohydrate immediately after racing
• Eat a meal in the evening
• Consider a pre-sleep snack
• Eat a carbohydrate-rich breakfast the next morning

That’s how race teams try to stack recovery.

4. Personalization matters. Not every athlete burns through glycogen at the same rate. Body size, stage profile, race role, and even individual metabolism all change the equation.That’s why a one-size-fits-all carb loading strategy often falls short. A GC rider, a domestique, and a recreational cyclist may all need different recovery plans.

5. Watch for the scale, not just performance. A lot of athletes worry about the weight gain that can come with aggressive carbohydrate loading. That concern is real, especially in sports where body mass matters.But the right question is not just “How much weight will I gain?” It’s also:

• How much glycogen did I lose?
• How soon do I need to perform again?
• What is the minimum intake that gets me back to ready?

That’s where individualized fueling becomes useful.

A few practical takeaways you can use right now

If you want the most useful summary of this study, it’s this:

• Liver glycogen can replenish quickly
• Muscle glycogen takes longer
• 10 g/kg over 12 hours restored liver glycogen, but not full muscle glycogen
• Mixed carbohydrate sources like sucrose may help liver recovery
• Total intake and timing matter more than perfection
• Sleep and practical meal timing still matter a lot

For endurance athletes, this supports a simple strategy: after a hard, glycogen-depleting session, start refueling early, keep carbohydrate coming in, and don’t assume one meal will fully restore your muscles by tomorrow.

Be sure to subscribe to stay up-to-date on the Nutritional Revolution podcast for more insights from leading experts and professional athletes. Episodes are available on our website, Apple, Spotify (and most streaming platforms), and the full video is up on YouTube.