The Science of Fueling: Glycogen and the 90-Minute Mark
Your body's primary source of energy during exercise is glycogen, which is stored in your muscles and liver. While running, your body utilizes this stored energy, but those stores are finite. For most people, particularly recreational runners, muscle glycogen becomes significantly depleted after about 75 to 90 minutes of continuous, moderate-to-high-intensity running. This is the point at which many runners begin to feel fatigue, or 'bonk'—the sensation of hitting the wall. A 10-mile race can take anywhere from just over an hour for a fast runner to well over 90 minutes for a newer or slower-paced athlete. This key distinction dictates whether mid-race calories are essential or simply a potential performance booster.
The Fast-Paced Runner (Under 75 Minutes)
For runners who expect to finish a 10-mile race in less than 75 minutes, mid-race fueling with food is generally unnecessary. The pre-race meal and proper carb-loading in the 24-48 hours prior to the event should be sufficient to power your effort. The primary focus for this group should be hydration. However, even faster runners can benefit from a mid-race mental boost. Some athletes find that a quick rinse with a sports drink (followed by spitting it out) can 'trick' the brain, providing a perceived energy lift without the digestive load.
The Endurance-Paced Runner (Over 75 Minutes)
If your 10-mile race is expected to take over 75-90 minutes, a mid-race fueling strategy is highly recommended. Replenishing carbohydrates during the race helps spare your muscle glycogen stores, maintain consistent energy levels, and delay the onset of fatigue. Experts generally recommend consuming 30-60 grams of carbohydrates per hour for runs exceeding 90 minutes, and starting your fueling early—around the 30 to 45-minute mark. Waiting until you feel low on energy is too late; it's a proactive, rather than reactive, strategy.
Fueling Options: Finding What Works for You
Experimenting during training is crucial to determine which fuel sources your stomach can tolerate best on race day.
- Energy Gels: These provide a concentrated, fast-absorbing dose of carbohydrates, often with added electrolytes. They are convenient to carry and ingest. Some runners find their sticky texture or taste difficult, and they can sometimes cause GI issues if not followed with water.
- Chews & Gummies: A solid, chewable alternative to gels, offering a more gradual release of energy. Many runners find these easier to digest and less likely to cause stomach distress than gels. They still contain significant sugar and require chewing, which can be difficult during high-intensity running.
- Sports Drinks: Combine hydration and carbohydrate delivery in one. This can be very efficient, but be mindful of the concentration. A high-carbohydrate sports drink without enough water can cause stomach upset. Look for a mix of glucose and fructose for better absorption.
- Whole Foods: Easily digestible options like bananas, raisins, or even pretzels offer a more natural source of carbs and electrolytes. The downside is that they can be harder to carry and may cause more digestive issues due to fiber content.
Hydration: A Non-Negotiable Partner to Fuel
Regardless of your fueling strategy, maintaining proper hydration is critical. Dehydration can rapidly impair performance and increase the risk of gastrointestinal issues. Aim to drink small amounts of water or an electrolyte drink every 15-20 minutes during the race. Electrolytes like sodium are lost through sweat and need to be replenished, especially in warmer conditions. Practicing your hydration plan during training runs is just as important as practicing your fueling.
Fueling Decision Comparison Table
| Feature | Sub-75 Minute Runner | Over-75 Minute Runner | High-Intensity Runner |
|---|---|---|---|
| Mid-Race Fuel? | Not essential, can skip | Yes, 30-60g carbs per hour | Optional, may provide mental edge |
| Best Fuel Type | Focus on pre-race fuel | Gels, chews, sports drinks | Carbohydrate rinse or gels for boost |
| Carb Timing | N/A | Every 30-45 minutes after start | As needed for boost |
| Hydration Plan | Essential from start to finish | Essential, especially with fuel | Critical for preventing GI distress |
| Training Emphasis | Practice pre-race meal | Practice timing and fuel type | Experiment with different strategies |
Conclusion
Ultimately, whether you should eat during a 10 mile race depends on your individual pace and goals. A faster runner completing the distance in under 75 minutes may not need mid-race calories, provided they have properly pre-fueled. However, for most runners, especially those taking longer than 90 minutes, strategically consuming 30-60 grams of carbohydrates per hour will be a vital part of a successful race. The most important thing is to train your gut, test different fuel options and timings during your long runs, and always prioritize hydration. By planning ahead and listening to your body, you can ensure you have the energy needed to finish strong.
Gut training link
For more information on training your gut to handle race-day nutrition, consult this resource: Why You Should Train Your Gut for Race Day.
