Hitting the wall at mile 20 is not inevitable. It is almost always the result of a fueling strategy that went wrong — started too late, used the wrong product, or was never properly practised in training. Running gels and energy products are your tools for avoiding the wall. Here is how to use them correctly.
Why You Need Mid-Race Fuel
Your body stores roughly 1,800 to 2,000 calories of glycogen in your muscles and liver — enough for approximately 90 to 120 minutes of sustained running. A marathon takes most runners 3.5 to 5+ hours. The math is simple: you will run out of glycogen before you cross the finish line unless you take in additional carbohydrates during the race.
Burning through glycogen and failing to replace it is what causes the dramatic slowdown known as bonking or hitting the wall. Proper fueling delays this by supplementing your body's stores throughout the race.
Types of Mid-Race Fuel
| Product Type | Carbs per Serving | Pros | Cons |
|---|---|---|---|
| Energy gels | 20–25g | Easy to carry, fast absorbing | Some runners dislike texture |
| Energy chews | 20–25g | More pleasant texture for many | Slower to chew while running |
| Sports drinks | 14–30g per 8oz | Fluid + carbs together | Heavy to carry |
| Real food (dates, bananas) | Varies | Familiar, whole food | Harder to digest at race pace |
| Hydrogel gels | 20–25g | Less GI distress for many | More expensive |
When to Take Gels During a Marathon
Start fueling early — at the 45-minute mark — rather than waiting until you feel tired or empty. By the time depletion hits your awareness, your blood sugar is already falling. A common schedule for a 4-hour marathon:
- Mile 6 (45–50 min): First gel
- Mile 10 (90 min): Second gel
- Mile 14 (2h 05min): Third gel
- Mile 18 (2h 45min): Fourth gel
- Mile 22 (3h 20min): Fifth gel (or chews)
Always take gels with water, not a sports drink. Combining a gel (concentrated sugar) with a sugary drink can overwhelm your gut and cause GI distress. Stick to water at gel stations.
Caffeine and Gels
Many gels contain 25 to 100mg of caffeine. Caffeine is a proven endurance aid — it reduces perceived effort and helps you push harder for longer. Save caffeinated gels for the second half of the race when mental and physical fatigue are setting in. If you do not regularly consume caffeine, test a caffeinated gel in training before relying on it on race day.
Avoiding GI Problems
Stomach issues during a marathon are frustratingly common. To minimize the risk:
- Practise your exact gel brand and flavour in training
- Avoid high-fibre and high-fat foods the day before the race
- Take gels with water, not sports drink
- Never try a new product on race day
- Consider hydrogel-format gels if standard gels have caused issues before
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Try PaceOverlay Free →Frequently Asked Questions
How many gels do I need for a marathon?
For most runners, 4 to 6 gels over a 3.5 to 5 hour marathon. That works out to roughly one gel every 30 to 45 minutes starting around 45 minutes in.
Can I use only sports drinks instead of gels?
Yes, if the race course offers adequate sports drink at aid stations. Make sure you know exactly what drink will be available and have tested it in training.
What is the best gel for sensitive stomachs?
Hydrogel-format products (such as Maurten) are designed to minimize GI distress. They use a gel matrix that changes consistency in the stomach and is easier to absorb. Many runners with gel intolerance do better with real-food alternatives like dates or banana pieces.
For complete race-day preparation, see our complete marathon training guide.
Final Thoughts
running gels energy during race is one of the most evidence-backed ways to improve your running performance. The techniques and principles here — spanning Why You Need Mid-Race Fuel, Types of Mid-Race Fuel — give you everything you need to train smarter rather than just harder.
The biggest gains come from consistent, progressive application over weeks and months — not from any single workout. Use this guide as your starting framework, track your results honestly, and adjust based on what your body tells you.