The role of carbohydrates: your primary energy source
For any run lasting longer than 60 to 75 minutes, your body's stored carbohydrates, known as glycogen, begin to deplete. Once these stores are low, you'll experience a sharp drop in energy, often referred to as "hitting the wall" or "bonking." To avoid this, it's essential to consume carbohydrates during your run to replenish your energy stores and sustain performance. The general recommendation is to consume 30–60 grams of carbohydrates per hour for runs lasting over 75 minutes. For ultra-endurance events, some athletes may benefit from up to 90 grams per hour, especially when using a blend of different carb sources like glucose and fructose.
Carbohydrates are broken down into glucose, which is used for immediate energy. Your body can absorb glucose and fructose through different pathways, making a blend of these sugars more efficient for higher intake rates and better for preventing gastrointestinal distress.
Choosing your fuel source: gels, chews, drinks, and real food
Runners have a wide variety of options for mid-run fuel, each with its own pros and cons. The right choice often comes down to personal preference and what your stomach can tolerate while running. It is crucial to experiment with different types during your training to discover what works best for you and prevent any unwanted surprises on race day.
- Energy Gels: These are concentrated sources of carbohydrates in a single, easy-to-carry packet. They are fast-absorbing and require consuming with water to aid digestion. Some are isotonic, meaning they don't require extra water, and some contain caffeine for an extra boost.
- Energy Chews or Blocks: These are bite-sized, chewy carbohydrates that allow for a more controlled, incremental intake. They are portable and can be easier to stomach than gels for some runners.
- Sports Drinks: These combine carbohydrates, fluids, and electrolytes into one solution, making them excellent for both fueling and hydrating simultaneously. Different concentrations and types are available, so finding one that agrees with your stomach is key.
- Whole Food Options: Many runners prefer real food for fueling, especially during lower-intensity or ultra-distance efforts. Examples include bananas, dates, raisins, maple syrup packets, or even small, boiled and salted potatoes. These can be gentler on the stomach but may require more effort to carry and consume.
Fuel options at a glance
| Fuel Type | Carbohydrate Source | Pros | Cons |
|---|---|---|---|
| Energy Gels | Maltodextrin, Fructose | Fast-acting, portable, high carb concentration | Can be hard to swallow, requires water, potential GI distress |
| Energy Chews | Maltodextrin, Fructose | Bite-sized, controlled intake, variety of flavors | Can be harder to chew while running, can stick together |
| Sports Drinks | Glucose, Maltodextrin | Replaces fluids and electrolytes, easy to consume | Can be bulky to carry, requires mixing, higher sugar content |
| Real Food | Natural Sugars (Fructose, Glucose) | Easier on stomach, natural ingredients, cost-effective | Can be bulky to carry, harder to consume quickly, can spoil |
Hydration and electrolyte balance
Staying hydrated is just as critical as fueling during a long run. As you sweat, you lose both fluid and essential electrolytes, especially sodium. Inadequate hydration can lead to fatigue, cramping, and a decline in performance. The typical recommendation is to consume 500–750ml of fluid per hour, though this varies based on individual sweat rate, run intensity, and environmental conditions.
Electrolytes, particularly sodium, are crucial for maintaining proper muscle function and fluid balance. For runs over 60–75 minutes, or in hot weather, it's recommended to supplement with electrolytes through sports drinks, electrolyte tablets, or salt capsules. Heavy or "salty" sweaters will need a higher sodium intake to compensate for greater losses.
- Assess your hydration: A simple way to check your hydration status is to monitor your urine color. It should be a pale yellow color, similar to lemonade. You can also weigh yourself before and after runs to estimate fluid loss and determine your ideal hourly intake.
Timing is everything: implementing your fueling strategy
Your fueling strategy is not a one-size-fits-all plan. It's a dynamic process that needs to be refined during your training. Here are some key timing principles:
- Start early: Begin taking fuel within the first 30–45 minutes of a long run to get ahead of glycogen depletion. Waiting until you feel low on energy is often too late.
- Practice the 'little and often' approach: Instead of consuming a large amount of fuel at once, take small, consistent amounts every 20-30 minutes. This helps avoid overwhelming your stomach and maintains steady energy levels.
- Train with your race day plan: The products and timing you use on race day should be thoroughly tested during your long training runs. Never experiment with new foods or gels on the day of the event.
Training your gut and preventing distress
Many runners experience gastrointestinal (GI) issues, but these can be minimized with preparation. The most common causes include reduced blood flow to the digestive tract during high-intensity exercise, dehydration, and poorly timed food choices.
Key strategies for gut training and GI prevention:
- Gradual build-up: Slowly increase your hourly carbohydrate intake during training runs to build your gut's capacity to absorb more fuel.
- Practice with different fuel types: The body adapts over time, so consistent exposure to your chosen fuel during training is essential.
- Mind your timing: Avoid consuming high-fiber, high-fat, or high-protein foods in the hours before a run, as they take longer to digest.
- Stay hydrated: Dehydration can worsen GI symptoms. Proper hydration helps your body absorb the carbohydrates you consume.
The role of caffeine during a long run
Caffeine is a popular ergogenic aid that can decrease the perception of effort and enhance performance, especially during endurance exercise. Caffeinated energy gels or sports drinks can provide a boost when fatigue starts to set in. However, it is essential to test your tolerance during training, as caffeine can cause jitteriness, anxiety, or further GI distress in some individuals. The recommended dosage varies, but a typical intake for performance is around 3-6mg per kilogram of body weight.
Conclusion
Fueling correctly during a long run is a personalized science that requires practice and attention to your body's signals. The key to success is developing a consistent strategy in training, focusing on a regular intake of carbohydrates and a vigilant approach to hydration and electrolytes. Whether you choose energy gels, real food, or a sports drink, the most important aspect is consistency and knowing what works best for you to maintain energy and prevent discomfort. By training your gut and paying close attention to your body's needs, you can confidently take on your next long run, mile after mile. For more detailed information on fueling strategies, consider reviewing resources like the Mayo Clinic Health System.
