The Science of Mid-Run Fueling
Your body's primary energy source during moderate to high-intensity exercise is carbohydrates, stored in the muscles and liver as glycogen. For runs lasting more than an hour, these glycogen stores become depleted, a state often referred to as 'hitting the wall'. Proper mid-run fueling is the strategic intake of carbohydrates to prevent this energy crash and maintain a steady performance. In addition to carbohydrates, runners lose electrolytes like sodium and potassium through sweat. Replenishing these minerals is essential for preventing dehydration, muscle cramps, and supporting muscle function.
When to Start Fueling
For runs under 60 minutes, most individuals can rely on their pre-run meal for energy. However, for runs longer than 60-75 minutes, or for high-intensity workouts, it's recommended to start taking in carbohydrates.
- Long Runs (1 to 2.5 hours): Aim for 30–60 grams of carbohydrates per hour.
- Ultra Distances (3+ hours): You may need to increase your intake to 60–90 grams of carbohydrates per hour and consider adding a small amount of protein.
- Timing: Spread your intake throughout the run, consuming a small amount every 30–45 minutes, rather than all at once.
Your Mid-Run Fuel Options
Choosing the right fuel depends on personal preference, digestive tolerance, and the duration of your run. Options range from purpose-built engineered fuel to natural whole foods.
Engineered Fuel
- Energy Gels: Highly concentrated sources of carbohydrates in a single-serving packet. They are quickly digested and often include electrolytes or caffeine. Popular brands include GU and Huma.
- Energy Chews: Gummy-like candies that provide carbohydrates in a more solid form. They offer a sustained release of energy and can be a good option for runners who prefer something to chew on.
- Sports Drinks: Provide carbohydrates and electrolytes in a fluid form, addressing both energy and hydration needs simultaneously. Examples include Gatorade and Nuun.
Real Food Options
- Bananas: A natural source of easily digestible carbohydrates and potassium, a key electrolyte. The riper the banana, the simpler the sugars and faster the absorption.
- Dried Fruits: Options like raisins, dates, and apricots offer concentrated carbohydrates. Raisins have been shown to be as effective as energy chews.
- Honey: Squeeze packets of honey are a simple, natural, and potent source of sugar for a quick energy boost.
- Salted Potatoes: Boiled, salted potatoes or sweet potatoes can provide carbohydrates and sodium, which is especially useful for ultra-runners.
- Simple Carbohydrates: White bread with honey or jam, or even jelly-based sweets, provide easy-to-absorb sugars without much fiber to slow digestion.
DIY Fuel Recipes
For those who prefer to control their ingredients, homemade options like watermelon chews or mocha honey fuel can be effective alternatives to commercial products.
Comparison Table: Fueling Options at a Glance
| Feature | Energy Gels | Energy Chews | Real Food (e.g., Banana) |
|---|---|---|---|
| Convenience | Excellent: small, easy to carry and consume. | Very Good: solid but compact, often resealable. | Good: requires carrying, can be messy. |
| Digestion Speed | Very Fast: liquid concentrate is absorbed quickly. | Fast: requires some chewing, but simple sugars are fast. | Moderate: depends on ripeness and other components. |
| Flavor Variety | Wide variety of flavors available. | Wide variety of flavors and textures. | Natural taste; less variety. |
| Electrolytes | Often includes electrolytes like sodium. | Some versions include electrolytes. | Potassium is a common natural electrolyte source. |
| Cost | Can be expensive per serving. | Less expensive than gels, but still a premium product. | Generally the most budget-friendly option. |
| Potential for GI Distress | Higher risk if taken quickly without water. | Less risk than gels if consumed slowly. | Generally low risk, but individual tolerance varies. |
How to Master Your Mid-Run Fueling Strategy
Practice in Training
Race day is not the time to test a new fuel. Use your long training runs to experiment with different types of fuel to see what works best for your body. Pay attention to how your stomach feels and whether the fuel provides a steady energy level or a quick spike and crash.
Hydration is Key
Your fueling and hydration plans are inseparable. Always drink water with your fuel, especially with concentrated sources like gels, to aid digestion and absorption. During runs, sip water regularly, and for longer distances or hot conditions, consider an electrolyte drink to replace lost salts. For more detailed guidance on proper hydration, consult expert advice on the topic, such as the resources found on sites like REI.com.
Listen to Your Gut
Every runner's digestive system is unique, and gastrointestinal tolerance can vary. If you experience stomach issues, try different types of fuel, vary your timing, or adjust the quantity. Avoid taking all your fuel at once; smaller, more frequent doses are often better tolerated.
What to Avoid During a Run
To prevent stomach upset and energy crashes, avoid these types of food and drink while running:
- High-Fiber Foods: Too much fiber can cause bloating and digestive issues mid-run.
- High-Fat Foods: Foods like fried items or heavy sauces take longer to digest, leaving you feeling sluggish.
- Spicy Foods: Can cause indigestion and heartburn during intense exercise.
- Excessive Caffeine: While a small amount can help, too much caffeine can cause jitters and an increased heart rate.
- Sugary Junk Food: Sweets and pastries offer a quick energy spike followed by a rapid, performance-sapping crash.
Conclusion
Mastering your mid-run nutrition is a critical component of successful endurance running. It's a highly individual process that requires careful planning and practice during training. By understanding your body's energy needs and experimenting with a variety of fuel sources—from convenient gels and chews to natural whole foods—you can develop a personalized strategy that keeps you energized and strong to the finish line. Always prioritize easily digestible carbohydrates, pair them with adequate hydration and electrolytes, and listen to what your body tells you throughout the process.
Visit REI's Running Nutrition Guide for more expert advice on fueling your runs.
