Running Nutrition: When and How to Fuel During Your Runs

Should I eat mid-run?

For runs exceeding approximately 60-90 minutes, strategic mid-run nutrition is not only beneficial but often crucial for maintaining performance, delaying fatigue, and supporting recovery by replenishing depleted carbohydrate stores.

The Science Behind Mid-Run Fueling

Understanding the body's energy systems is fundamental to appreciating the role of mid-run nutrition. During endurance exercise like running, your primary fuel sources are carbohydrates (stored as glycogen in muscles and liver) and fats. While fat stores are virtually limitless, carbohydrate stores are finite.

• Glycogen Depletion: Your body typically stores enough glycogen for about 60-90 minutes of moderate-to-high intensity running. Once these stores are significantly depleted, you experience the dreaded "bonk" or "hitting the wall," characterized by severe fatigue, reduced pace, and impaired cognitive function.
• Exogenous Carbohydrates: By consuming carbohydrates during your run, you provide an external source of glucose that can be rapidly absorbed and utilized for energy, sparing your internal glycogen stores and extending your ability to perform. This helps maintain blood glucose levels, which are critical for both muscle function and brain activity.

When Mid-Run Fueling Becomes Crucial

The necessity of mid-run fueling is primarily dictated by the duration and intensity of your run.

• Runs under 60 minutes: For shorter, less intense runs, your existing glycogen stores are generally sufficient, and mid-run fueling is typically unnecessary. Focus on proper pre-run nutrition and post-run recovery.
• Runs 60-90 minutes: For runs approaching or slightly exceeding an hour, especially at higher intensities, a small amount of easily digestible carbohydrates may be beneficial, particularly if you haven't fueled adequately beforehand or are prone to hitting the wall.
• Runs over 90 minutes: This is where mid-run fueling becomes essential. For long runs, marathons, or ultra-marathons, consistent carbohydrate intake is non-negotiable to sustain performance and prevent severe glycogen depletion.

Benefits of On-Course Nutrition

Proper mid-run fueling offers several significant advantages for endurance athletes:

• Sustained Energy and Performance: Provides a continuous fuel supply to working muscles, helping to maintain pace and power output.
• Delayed Fatigue: Prevents or significantly delays the onset of glycogen depletion and the associated fatigue, allowing you to run stronger for longer.
• Improved Mental Focus: Maintains blood glucose levels, which are vital for brain function, helping to keep you sharp and focused throughout your run.
• Enhanced Recovery: By minimizing the extent of glycogen depletion during the run, you reduce the carbohydrate deficit that needs to be replenished post-exercise, potentially aiding in quicker recovery.
• Reduced Muscle Breakdown: Adequate carbohydrate availability can help spare muscle protein from being broken down for energy.

Optimal Fuel Sources for Mid-Run

The best mid-run fuel sources are those that are rapidly digestible, easily absorbed, and primarily carbohydrate-based, with minimal fat, fiber, or protein, which can slow digestion and cause gastrointestinal (GI) distress.

• Energy Gels: Highly concentrated carbohydrate sources, often with added electrolytes. Easy to consume quickly.
• Energy Chews/Blocks: Similar to gels but in a chewable, solid form. Can offer a psychological benefit of "eating" something.
• Sports Drinks: Provide carbohydrates and electrolytes in liquid form, aiding hydration simultaneously. Ensure they are isotonic or hypotonic for optimal absorption.
• Dried Fruit: Natural source of simple sugars. Good for those preferring whole foods, but can be higher in fiber.
• Pretzels/Crackers: Provide simple carbohydrates and sodium. Can be a good option for those needing something more solid, but consume in small amounts.
• Small Portions of Easily Digestible Foods: Some runners tolerate things like half a banana, rice cakes, or small pieces of white bread, but these require more chewing and can be harder to digest for some.

Avoid high-fat, high-fiber, or high-protein foods during runs, as they slow gastric emptying and can lead to GI issues like cramping, bloating, or nausea.

How Much to Consume

General guidelines for carbohydrate intake during endurance exercise:

• 60-90 minutes: 30-60 grams of carbohydrates per hour.
• 90 minutes - 2.5 hours: 30-60 grams of carbohydrates per hour.
• Over 2.5 hours: 60-90+ grams of carbohydrates per hour, often requiring a blend of glucose and fructose for optimal absorption (e.g., maltodextrin and fructose).

Individual variability is key. Start with the lower end of the recommendation and gradually increase as your gut adapts and you determine your personal tolerance.

Timing Your Fuel Intake

• Start Early: Don't wait until you feel depleted. Begin consuming carbohydrates within the first 45-60 minutes of your run, especially if it's a longer effort.
• Small, Frequent Doses: Rather than consuming a large amount at once, aim for smaller, more frequent intakes. For example, a quarter of an energy gel every 15-20 minutes, or sips of a sports drink every 10-15 minutes. This helps maintain a steady energy supply and minimizes the risk of GI distress.
• Hydrate with Fuel: When consuming gels or chews, always follow them with water. This aids absorption and prevents dehydration.

Common Pitfalls and How to Avoid Them

• Gastrointestinal (GI) Distress: The most common issue. Often caused by consuming too much, consuming the wrong type of fuel (e.g., too much fiber/fat), or not practicing fueling during training.
  • Solution: Practice, practice, practice! Experiment with different fuels and quantities during training runs to find what works for you. Stay hydrated.
• Under-Fueling: Not consuming enough carbohydrates, leading to bonking.
  • Solution: Follow guidelines for carbohydrate intake based on run duration. Be proactive with fueling.
• Over-Fueling: Consuming too many carbohydrates, leading to GI distress or feeling overly full.
  • Solution: Stick to recommended intake ranges and listen to your body.
• Trying New Fuels on Race Day: A recipe for disaster. Your body needs to be accustomed to the fuels you'll use.
  • Solution: Only use fuels that you have successfully trained with, especially in conditions similar to your race.

Training Your Gut

Just as you train your muscles, you can train your gut to better absorb and tolerate carbohydrates during exercise.

• Consistency: Regularly practice your fueling strategy during long training runs.
• Gradual Increase: Slowly increase the amount of carbohydrates you consume per hour over time.
• Variety (in training): Experiment with different types of fuels (gels, chews, drinks) to see what your body handles best.
• Race Simulation: Practice your exact race-day fueling plan during training runs that mimic race intensity and duration.

Individual Considerations

While general guidelines exist, your personal fueling strategy will be unique. Factors influencing your needs include:

• Pace and Intensity: Higher intensity burns more carbohydrates.
• Environmental Conditions: Hot and humid conditions increase fluid and electrolyte needs, and can affect GI comfort.
• Personal Tolerance: Some individuals have more sensitive stomachs than others.
• Pre-Run Nutrition: Adequate pre-run fueling can slightly extend the time before mid-run intake is critical.

Conclusion: Fuel Smart, Run Strong

Eating mid-run is a vital component of successful endurance running for efforts exceeding 60-90 minutes. By understanding the science of energy metabolism, identifying optimal fuel sources, practicing your fueling strategy, and listening to your body, you can optimize your performance, prevent fatigue, and enhance your overall running experience. Don't leave your fueling to chance; make it an integral part of your training and race-day plan.