Maximising Glycogen Storage: The Key to Athletic Success? - truefuels

Maximising Glycogen Storage: The Key to Athletic Success?

The speed read

Glycogen is the stored form of glucose in our muscles and liver. It’s essential for endurance, high-intensity efforts, and recovery. When glycogen runs low, performance declines. When it’s optimised, you can push further and recover faster. In this post, I explain what glycogen is, how it works, and how to store more of it, so your training doesn’t just feel good, it performs well.

Glycogen is your body’s stored fuel, glucose tucked away in muscles and liver to power endurance, high-intensity efforts, and recovery. Low glycogen means fading performance; optimised glycogen means pushing harder and bouncing back faster. Here’s the science of glycogen, how it works, and how to store more to make your training thrive.

What is Glycogen?

Glycogen is a chain of glucose molecules stored in your liver and skeletal muscles, ready to fuel exercise. Each gram of glycogen holds ~3 grams of water, explaining why carb-heavy diets can cause weight fluctuations (Murray & Rosenbloom, 2018). It’s not just about how much you store—it’s where and when it’s used that matters.

Muscle Glycogen: Performance on Tap

Your muscles store 300–800 grams of glycogen, depending on training and diet, fuelling both long runs and quick sprints. Glycogen is stored in three ways:

  • Most (~75% - Intermyofibrillar) surrounds muscle fibres, powering sustained efforts like long rides.
  • Some (5–15% - Intramyofibrillar) sits inside fibres, driving explosive movements like sprints.
  • A bit (5–15% - Subsarcolemmal) lies near the muscle surface, supporting low-intensity activity and maintenance.

When these stores run low, fatigue hits hard. Legs feel heavy, pace slows, and intensity fades.

Liver Glycogen: Glucose in Reserve

Your liver stores 80–100 grams of glycogen to maintain blood glucose, especially during fasting or workouts beyond 90 minutes (Radziuk & Pye, 2001). These reserves keep your brain and nervous system sharp, preventing issues like dizziness or shakiness. Deplete them, and you risk hypoglycaemia, causing irritability, poor coordination, and a very slow ride home(been there!)

How Do You Know If You’re Low on Glycogen?

Low glycogen shows up differently by sport:

  • Running: Slower pace, heavy legs, or “hitting the wall” in a marathon, often with mental fog.
  • Cycling: Power drops at moderate efforts, with cold sweats or nausea as warning signs. My legs go weak, and I get a headache.
  • Swimming: Technique slips, core weakens, and rhythm falters, with longer stares at the pool clock.

These probably signal glycogen depletion, not just tiredness.

Why Glycogen Matters in Endurance Sports

Glycogen fuels muscle contractions and stabilises blood glucose. Even with ~800g of stores (~3,200 calories), enough for 3–5 hours of cycling at a moderate 200 watts, it can be the limiting factor. When glycogen runs low, fat and protein can’t fully compensate, tanking performance and recovery (Hawley et al., 2011). We can maintain

Proper fuelling during intense exercise is critical for sparing glycogen stores and sustaining performance, particularly in endurance or high-intensity activities lasting over 60–90 minutes. In my experience, adequate fuelling enhances my fatigue resistance, allowing me to sustain intense efforts throughout a race or event. By fuelling correctly with carbohydrates, athletes can sustain power output, improve endurance, and minimise performance declines, ensuring they finish strong even in demanding conditions (Burke et al., 2011).

How to Maximise Glycogen Storage

1. Prioritise Daily Carbs

Aim for 6–10g of carbs per kg of body weight daily (e.g., 420–700g for a 70kg athlete) from whole grains, fruits, and sports nutrition. For events >90 minutes, carb-load with 10–12g/kg for 48–72 hours pre-race to max out muscle and liver stores (Kerksick et al., 2018).

2. Refuel Within 30 Minutes Post-Exercise

Muscles are primed for glycogen storage post-workout. Consume 1.0–1.2g/kg of carbs with 0.3–0.4g/kg of protein (e.g., oats with yoghurt or a banana-protein shake) to boost recovery (Ivy et al., 2002).

3. Eat Regularly

Balanced meals every 2–4 hours post-training support ongoing glycogen replenishment, reducing fatigue for next-day sessions.

4. Train to Store More

Endurance training boosts glycogen storage and fat oxidation, sparing glycogen during long efforts. This is why seasoned athletes feel stronger longer (Hawley et al., 2011).

The Risks of Glycogen Depletion

Low glycogen slows recovery, disrupts mood, sleep, and immune function, and risks overtraining during high-load weeks or stage races. It’s not just heavy legs, it’s a performance killer.

Final Thoughts

Glycogen is a real edge for endurance performance, stock it well to finish strong. Watch for depletion signs, eat carbs consistently, and refuel early. Your next session depends on it.

Want to simplify recovery? Explore our high-carb gels to replenish glycogen fast and stay ready.

References

About the Author

Alistair Brownlee is a two-time Olympic gold medallist, Ironman Champion, and co-founder of Truefuels. He is driven by a belief in science-backed training, clear structure, and removing friction from performance.

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