For any runner tackling distances that push past the 90-minute mark, a well-executed fueling strategy is as critical as their training plan or running shoes. The essential practice involves consuming easily digestible carbohydrates and electrolytes, starting approximately 30 to 45 minutes into the effort and continuing in regular intervals. This mid-run nutrition is vital for replenishing the body’s limited energy stores, primarily muscle glycogen, to prevent the dreaded performance crash known as “bonking” or “hitting the wall.” By strategically consuming fuel on the move, runners can sustain their energy, maintain mental focus, and ultimately improve both their performance and post-run recovery.
Why Fueling During a Long Run is Non-Negotiable
To understand the importance of mid-run fueling, you first need to understand how your body powers itself during sustained exercise. Your muscles and liver store a finite amount of carbohydrates in a form called glycogen. Think of this as the high-octane fuel in your personal energy tank.
When you run, your body taps into these glycogen stores to produce the energy required for muscle contraction. However, this tank is relatively small; most trained athletes have enough glycogen to power about 90 to 120 minutes of moderate-to-high intensity effort. Once these stores run critically low, your body is forced to rely more heavily on fat for energy.
While we all have plenty of fat to burn, converting it to usable energy is a much slower, less efficient process that cannot support the same level of intensity. This metabolic shift is the physiological event runners call “bonking” or “hitting the wall.” It’s characterized by a sudden and dramatic drop in energy, profound fatigue, dizziness, and even mental confusion. Proper fueling is the proactive measure you take to prevent this from ever happening.
By supplying your body with a steady stream of external carbohydrates during your run, you spare your precious stored glycogen, allowing you to maintain your pace and effort for a longer duration. This isn’t just about elite performance; it’s about making your long runs more enjoyable, effective, and sustainable, while also setting your body up for a quicker recovery.
The Science of Mid-Run Fuel: Carbohydrates and Electrolytes
The science behind mid-run nutrition is centered on two key components: fast-acting carbohydrates for energy and essential electrolytes for function. Understanding their roles helps you make smarter choices about what to consume on the move.
Carbohydrates: Your Primary Energy Source
Carbohydrates are the undisputed king of endurance fuel. During a run, your body needs simple sugars—like glucose and fructose—that can be absorbed into the bloodstream quickly and transported to working muscles with minimal digestive effort. Complex carbohydrates, like those found in whole grains or fibrous vegetables, are fantastic for daily health but are too slow to digest during intense exercise.
The general scientific recommendation is to consume between 30 and 60 grams of carbohydrates for every hour of running after the first hour. For very long efforts like marathons and ultramarathons, highly trained athletes may even push this up to 90 grams per hour by using fuel sources that contain a multi-transportable blend of carbohydrates (like a glucose-fructose mix), which can increase the rate of absorption.
Electrolytes: The Spark Plugs of Your Muscles
While carbohydrates provide the fuel, electrolytes are the spark plugs that ensure your muscular and nervous systems function correctly. These essential minerals—primarily sodium, potassium, magnesium, and calcium—are lost through sweat. Sodium is the most critical electrolyte to replace during endurance exercise.
Electrolytes are responsible for maintaining proper fluid balance, facilitating nerve impulses, and enabling muscle contractions. An imbalance, most commonly caused by significant sweat loss, can lead to issues ranging from muscle cramps and weakness to more serious conditions like hyponatremia (dangerously low blood sodium levels). Most sports-specific fuels contain a balanced profile of these key electrolytes to help you replace what you lose.
The Role of Hydration
Fueling and hydration are intrinsically linked. Your body needs water to help process and transport the carbohydrates you consume. Furthermore, dehydration itself is a major cause of performance decline. Even a small percentage of fluid loss can increase your heart rate, elevate your core temperature, and make your run feel significantly harder.
The goal is to drink to thirst but also to have a plan. Sipping water or an electrolyte drink alongside your chosen fuel not only aids digestion but also ensures you are replacing fluids lost through sweat. In hot and humid conditions, hydration becomes even more critical.
Choosing Your Fuel: Gels, Chews, Drinks, and Real Food
The sports nutrition market is filled with options, each with its own set of benefits and drawbacks. The best choice often comes down to personal preference, digestive tolerance, and convenience. Experimenting during your training runs is the only way to find what works for you.
Energy Gels
Energy gels are the most common form of mid-run fuel. They are concentrated packets of simple carbohydrates, often with added electrolytes and sometimes caffeine. Their main advantage is convenience; they are lightweight, easy to carry, and deliver a pre-measured dose of around 20-25 grams of carbs.
The primary drawback for some runners is the texture, which can be thick and syrupy. It is almost always recommended to consume a gel with a few sips of water to dilute it, aiding both absorption and palatability. Trying different brands is key, as viscosity and flavor profiles vary widely.
Energy Chews or Gummies
Energy chews offer a solid-food alternative to gels. They provide a similar formulation of simple carbohydrates and electrolytes but in a gummy-like form. Many runners prefer the texture and the ability to portion their intake more granularly, eating one or two chews at a time instead of a whole packet at once.
The downside is that they require chewing, which can be difficult while breathing hard at a fast pace. They can also be sticky and a bit more cumbersome to get out of the package while on the move.
Sports Drinks
Sports drinks offer a three-in-one solution, delivering carbohydrates, electrolytes, and hydration simultaneously. For runners who struggle to stomach gels or chews, sipping on a sports drink throughout their run can be an excellent and effective strategy. It provides a constant, slow drip of energy.
However, relying solely on sports drinks can be challenging. It can be difficult to know if you are getting enough carbohydrates without drinking an excessive amount of fluid, which can lead to stomach sloshing. They are also bulkier to carry than gels or chews unless you are running a race with well-stocked aid stations.
Real Food Options
For some athletes, especially those running ultramarathons or those with sensitive stomachs, engineered sports products can lead to flavor fatigue or gastrointestinal (GI) distress. In these cases, real food can be a fantastic option. The key is to choose foods that are high in simple carbs and low in fat, fiber, and protein to ensure easy digestion.
Excellent real-food choices include small pieces of banana, pitted dates, applesauce pouches, pretzels, or even small boiled potatoes rolled in salt. While highly effective, these options are generally less convenient to carry and harder to consume without breaking stride.
Creating Your Personal Fueling Strategy
A successful fueling plan is a personal one, developed through consistent practice. The mantra every runner should live by is: nothing new on race day.
Timing is Everything
Do not wait until you feel your energy dipping to take your first fuel. By then, it’s too late, and you’ll be playing catch-up. Start fueling around 30-45 minutes into your run, even if you still feel strong. This proactive approach keeps your energy levels stable from the beginning.
After that initial fuel, aim to take in more carbohydrates every 30-45 minutes. Setting a recurring alarm on your watch can be an incredibly helpful reminder to stay on schedule.
Practice, Practice, Practice
Use every long run as an opportunity to rehearse your race-day fueling strategy. This serves two purposes. First, it helps you dial in the specific products, flavors, and timing that work for your body. Second, it trains your gut.
The gut is highly adaptable. By consistently consuming carbohydrates during exercise, you can actually improve your stomach’s ability to tolerate and absorb fuel on the move, reducing the risk of GI issues when it matters most.
Listening to Your Body
While having a plan is crucial, you must also learn to be flexible. Pay attention to how you feel. If you are running in extreme heat, you may need more fluids and electrolytes. If the intensity is higher than planned, you might need to fuel slightly earlier or more frequently.
Learn the signs of under-fueling (lightheadedness, a sudden desire to walk, negative self-talk) and over-fueling (bloating, side stitches, nausea). Adjust your plan accordingly based on the feedback your body is giving you.
Ultimately, fueling during a long run is a skill that transforms you from someone who simply endures the distance to someone who can perform well throughout it. By understanding the science, experimenting with different options, and consistently practicing your strategy, you can unlock new levels of endurance. The right fuel, taken at the right time, ensures your body has what it needs to carry you strong all the way to the finish line.
