Energy gels are highly concentrated carbohydrate sources designed to provide rapid fuel for endurance exercise. They are a popular and convenient tool for athletes, such as marathon runners and long-distance cyclists, who need to maintain performance over extended periods. Understanding the science of how the body fuels itself during prolonged physical activity answers the question of whether energy gels work. They deliver readily available energy to working muscles, helping to delay fatigue from depleted fuel stores.
The Science Behind Rapid Fueling
When the body engages in prolonged, intense exercise, its primary fuel source is carbohydrate, stored in the muscles and liver as glycogen. Glycogen stores are limited and typically last for about 90 minutes of continuous activity, depending on intensity and training level. Once these stores fall too low, the body experiences a significant drop in performance, often called “hitting the wall.”
Energy gels are formulated to provide exogenous carbohydrate to prevent this depletion. They contain high glycemic index carbohydrates that the body can quickly break down. The gel format, a semi-liquid concentration, is designed for extremely fast gastric emptying, allowing carbohydrates to move quickly from the stomach to the small intestine.
From the small intestine, the sugars are rapidly absorbed into the bloodstream, where they help maintain blood glucose levels. This steady supply of circulating glucose provides immediate energy for the brain and spares muscle glycogen stores, delaying fatigue and allowing the athlete to sustain effort longer.
Key Ingredients and Formulation Differences
The primary fuel source in most energy gels is maltodextrin, a carbohydrate made up of multiple glucose units linked together. Although chemically complex, maltodextrin is digested very quickly, providing the rapid glucose delivery needed during exercise.
A significant difference between gel formulations lies in the inclusion of fructose alongside maltodextrin. Glucose and fructose use different transport proteins in the small intestine to enter the bloodstream. By combining both, often in a 2:1 ratio of glucose to fructose, the body can utilize two separate transport pathways simultaneously, maximizing the total amount of carbohydrate absorbed per hour. This dual-carb strategy increases absorption capacity, helping athletes meet high energy demands without overwhelming a single digestive pathway. Some gels may also contain supplemental ingredients, such as electrolytes to replace minerals lost through sweat, or caffeine to enhance alertness.
Strategic Use and Timing
For endurance activities lasting longer than 90 minutes, a systematic fueling strategy is necessary for optimal performance. The general recommendation for athletes in prolonged events is to consume between 30 and 60 grams of carbohydrate per hour. For very long or intense events, especially when using dual-carb gels, some athletes can tolerate and benefit from up to 90 grams of carbohydrate per hour.
The first gel should be consumed early in the activity, typically around 45 to 60 minutes after starting, and before any significant fatigue sets in. This proactive approach ensures a steady energy supply is circulating before the body’s internal stores become severely depleted. Following the initial intake, subsequent gels should be consumed every 30 to 45 minutes to maintain the required hourly carbohydrate target.
It is important to consume most energy gels with water, as their high concentration requires fluid for efficient digestion and absorption. Taking a gel without sufficient water can draw fluid into the stomach, slowing absorption and potentially leading to gastrointestinal discomfort.
Practical Considerations and Alternatives
Despite their effectiveness, energy gels can sometimes cause gastrointestinal (GI) distress, including cramping, bloating, and nausea. This is often due to the high concentration of sugar, which is difficult to process when blood flow is diverted away from the gut to the working muscles during intense exercise. To minimize discomfort, athletes must practice their fueling strategy during training to allow the gut to adapt to processing carbohydrates under stress.
Energy gels are not the only option for mid-activity fueling. Alternatives like sports drinks offer both carbohydrate and hydration, while chews and bars provide a more solid food feel. Gels remain popular due to their small size, portability, and the rapid speed at which their concentrated liquid form delivers fuel. For an athlete prioritizing the fastest possible absorption and convenience during a race, the energy gel often remains the most effective choice.