Energy Gels

A typical energy gel contains 20 to 25 grams of carbohydrates. At a target intake of 60 to 90 grams per hour for a marathon lasting two to five hours, most runners need five to eight gels across the race, spaced roughly every 20 to 30 minutes. The exact number depends on whether you supplement with a carbohydrate drink mix, which reduces the number of gels needed. Practice your specific gel schedule in long training runs before race day.

Most gels require water for dilution in the stomach. Consuming a concentrated gel without water can draw fluid into the gut through osmosis, causing nausea and cramping. The exception is isotonic gels, which are pre-diluted to a concentration similar to blood and do not require additional water. If you use a standard concentrated gel, take it with three to five sips of water at an aid station or from your bottle.

Regular gels are concentrated carbohydrate syrups with an osmolality significantly above blood levels. They require water for proper absorption. Isotonic gels have an osmolality close to blood, around 280 to 300 milliosmoles per kilogram, meaning they can pass through the stomach without drawing additional water from the body. This reduces the risk of gastrointestinal distress but typically results in a larger gel packet because of the added fluid volume.

Begin fueling within the first 30 to 45 minutes of an event lasting over 75 minutes. Starting early maintains blood glucose before fatigue sets in and avoids the common mistake of waiting until you feel depleted. Glycogen depletion causes the performance decline known as bonking, and it is easier to prevent than reverse. Early and consistent intake at regular intervals produces steadier energy than reactive fueling after symptoms appear.

They can, and the causes are identifiable. Concentrated gels taken without water create osmotic stress in the stomach. Consuming fructose faster than roughly 30 grams per hour overwhelms the GLUT5 transporter, leaving unabsorbed sugar to ferment in the intestines. Caffeine in some gels stimulates gut motility and can trigger urgency. The most reliable prevention is testing every gel brand and flavor during training at race intensity before relying on it in competition.

Caffeine at a dose of 3 to 6 milligrams per kilogram of body weight improves endurance performance by reducing perceived effort and increasing time to exhaustion, according to meta-analyses published in the British Journal of Sports Medicine. Most caffeinated gels contain 20 to 100 milligrams per packet, so they contribute to but rarely fulfill an entire performance dose on their own. Many athletes use non-caffeinated gels throughout a race and switch to caffeinated gels in the second half when fatigue peaks.

Keep gels at room temperature in a dry location. Heat above 30 degrees Celsius can change the consistency and make packets harder to open. Cold temperatures thicken some formulations. For race day, place gels in accessible locations where you can reach them with one hand. Pin them to your race belt, tape them to your top tube, or tuck them into the waistband of your shorts. Pre-tear the corner of each packet so you can open it quickly while running or riding.