According to science, taking gels during a marathon may improve your marathon time by 10 minutes (or ~4.7%!)
Taking carbohydrates during long or intense competition, such as a marathon, is a scientifically proven way to improve your performance. Carbs provide direct energy by keeping your blood glucose stable, and they also give a helpful boost to your brain. As a result, you do not hit the wall, your muscles have enough substrate to keep pushing, and your nervous system is more resistant to fatigue.
Gels are simply one of the easiest ways to take carbs during a marathon. A gel is a concentrated semi-solid formula that allows you to consume a large amount of carbohydrates without chewing. The gel formula packs a lot of carbs into a small amount, so that your stomach doesn’t become jostled from a large volume of food.
How often should you take gels during a marathon?
On some gels, the manufacturer’s instructions suggest taking a gel every 45 minutes. For years, runners followed this approach – often with mixed results.
If you consumed a gel every 45 minutes during a four-hour marathon, you would take five gels. At 20-25 grams of carb for a standard gel, that equates to approximately 25-30 grams of carbs per hour.
Recent research has established that a gel every 45 minutes is not enough to fuel your next marathon.
One recent study compared cyclists taking gels at 30-minute and 45-minute intervals over a 2-hour steady ride, followed by a 15-minute time trial. Those who took a gel every 30 minutes had higher blood glucose levels – and a 5.4% better performance over the time trial.
Now, we understand that you need 60-90 grams of carbs per hour for a marathon. That is double to triple the recommendation from the back of the gel package!
Sample marathon fueling plans
You can reach 60-90 grams of carbs per hour by:
- Take a standard 20-25 gram carb gel every 20-25 minutes
- Take a standard gel every 25-30 minutes, plus drink a serving of sport drink per hour
- Use high-carb gels (30-50 grams of carbs) every 30 minutes
How many gels to take for a marathon, based on finish time:
- 2:30-3:00 hour marathon: 4-6 gels
- 3:00-3:30 hour marathon: 5-7 gels
- 3:30-4:00 hour marathon: 6-8 gels
- 4:00-4:30 hour marathon: 7-9 gels
- 4:30-5:00 hour marathon: 8-10 gels
- 5:00-5:30 hour marathon: 9-11 gels
- 6:00-6:30 hour marathon: 11-13 gels
And yes, that is a lot of gels – but it pays off! Here are some ways you can carry gels during your marathon.
Do gel recommendations scale based on body size?
The science has not progressed to the point of individualized carbohydrate recommendations yet, However, that doesn’t mean that your needs may not vary within the recommended ranges.
Previously, it was believed that carbohydrate oxidation rates were independent of body mass. New research indicates that body height may be a contributing variable, but body mass (independent of height) may not be a significant variable. Other variables, such as carbohydrate oxidation rates (which are trainable), impact fueling response.
In coaching, I have observed that some taller or larger runners feel best if they fuel on the higher end of the range (75-90 grams/hr). On the contrary, some runners cannot tolerate that much fuel and feel best at 60 grams/hr.
Regardless of body height or mass, you should experiment with carb intake in training. Start on the lower end (60 grams/hr) and see how you feel. If you feel like you need more and do not experience GI upset, scale it up.
If you feel best with higher carb intakes (75-90 grams per hour), then take the appropriate number of gels to achieve that on race day.
Some runners use very high carb fueling (90-120 grams of carbs per hour). In that scenario, you may feel best with a combination of liquid carbs and gels. A gel every 10-15 minutes would simply increase the risk of gastrointestinal distress, and it would also become logistically difficult.
If you use a high-carb approach, take a gel every 20-25 minutes and sip frequently at a higher-carbohydrate sport drink. Alternatively, you can use very high-carb gels, such as Carbs or SIS Beta. These gels contain 40-50 grams per serving, making it easier to hit your high-carb fueling goals.
Take a gel before your marathon
Once you have calculated how many gels you need during the race itself, make sure you pack one more gel for before the marathon starts.
Even if you ate a pre-race meal (which you should for peak performance!), both research and practice demonstrate the benefit of taking one gel 15 minutes before the race start.
For most athletes, rebound hypoglycemia is not a concern. A pre-race gel raises your blood glucose before the race, which is beneficial if you are burning off energy with pre-race nerves. Plus, a gel before the race brings some blood flow into your gut before you get running, which may be favorable for gastric emptying and reducing the risk of GI upset during the race itself.
How often should diabetic runners take gels?
If you have diabetes, I highly recommend consulting with a sports dietitian on your fueling plan. For basic reference, I encourage reading this article from Runner’s World on fueling long runs if you have type 1 or type 2 diabetes.
Alternatives to gels during a marathon
If you do not like gels, you can get your carbohydrates from sports drinks, energy chews, or some whole foods. Each has its downsides, though, so plan carefully and practice in training.
Sports drinks provide carbohydrates, electrolytes, and fluid all in one convenient beverage. Even if you use gels during a marathon, you will benefit from having a sports drink for the fluid and sodium.
Theoretically, you could rely solely on a sports drink during a marathon. Brands such as Skratch, Maurten, and Tailwind make high-carb sports drinks to help you meet the recommended intake for a marathon. However, the logistics are difficult. Either you carry a large amount of fluids from the start (which you could in a hydration vest), or you carry refill packets and plan to stop at aid stations periodically.
Energy chews are another popular sports nutrition product. As the name implies, chews are a gummy-like product that you have to chew. Typically, you have to eat a higher volume of chews to hit the same intake as a gel. Some runners like how chews are more palatable than a gel.
If you use exclusively chews, you may have to eat quite a lot over the course of the marathon. Some runners use a mix of chews, sports drink, and/or gels throughout the marathon. As long as you are getting in the recommended amount of carbs, mixing gels with chews can be a useful strategy to prevent palate fatigue in the marathon.
Some runners opt for whole foods, such as gummy candy or applesauce pouches. If you take this approach, be mindful of how much volume you may need to eat – and whether than volume could make you feel too full while running a marathon.
A recent study in the European Journal of Sport Science demonstrated that applesauce pouches can be used as a carbohydrate source during runs. However, the study only looked at GI symptoms over a half marathon. Large amounts of fructose can increase the risk of runner’s trots, so it is not clear how well high-fructose applesauce would be tolerated over a marathon. As with chews, you can use a mix of applesauce (or other whole foods) with gels to hit your hourly carbohydrate goals.
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