Are you feeling sluggish after 5-10 miles of running? If so, you are probably running low on glycogen (carbohydrates) and need to replenish them before they run out and you bonk!

Here is a quick guide to energy gels:


Health Science 101:

Carbohydrates are arguably the most important source of energy for athletes. No matter what sport you play, carbs provide the energy that fuels your muscles. Once carbs enter your body, they break down into smaller particles (glucose, fructose and galactose) that get absorbed and used as energy. Glucose not immediately needed gets stored in the muscles and the liver in the form of glycogen. Once these glycogen stores are filled up, any extra gets stored as fat. Glycogen is the source of energy most often used by your muscles while running because it is immediately accessible. If the body does not have enough carbohydrates, protein is broken down to make glucose for energy. Because the primary role of protein is as the building blocks for muscles, bone, skin, hair, and other tissues, relying on protein for energy (by failing to take in adequate carbohydrate) can limit your ability to build and maintain those tissues. Additionally, this stresses the kidneys because they have to work harder to eliminate the by-products of this protein breakdown.  What’s the point? You want to have adequate glycogen backups for peak performance during runs.

How Do Energy Gels Work?

Generally, the faster you run, the greater the percentage of your fuel that will come from carbohydrates. The problem with carbohydrates is that we can only store a limited amount in our muscles – about 90 minutes worth when running at fast pace and about 2 hours when running at slower pace. So, if you’re not an elite athlete, you’ll be bonking long before you cross the finish line of a 1/2 or full marathon. Energy gels are designed to replenish carbohydrates that are depleted when running, but this process takes time and is not super efficient. For the glycogen from an energy gel to make its way to the muscles, it must first make its way through the intestinal wall, and then be absorbed by the muscles before you notice the effects – this can take 15-45 minutes or more depending on many factors. Energy gels help replenish the glycogen you’re burning when running hard; however timing and frequency are critical factors.

When to take them?

You should begin taking gels relatively early in the run, since your stomach will process the gel faster (blood flow to the stomach decreases as intensity and length of run increases, making your stomach less efficient at digestion). Take your 1st gel somewhere between 45-60 minutes (depending on how well you generally react to gels in training) and every 45-60 minutes thereafter. You should train with gels so that your body will learn to keep the digestive track running and you are able to digest the gel more readily than taking them for the 1st time on race day.  Always take energy gels with water to help them absorb better into the bloodstream.

Which Gel to Use?

Available in an array of flavors, energy gels also typically contain varying amounts of electrolytes and other “non-essentials” such as herbs and caffeine. Find a brand and flavor that tastes good and has a consistency you can stomach. Keep in mind that in controlled amounts, caffeine ingested during exercise has not been shown to cause dehydration and it may improve your performance in endurance activities. For comparison, a 6-ounce cup of brewed coffee contains on average 85 mg of caffeine. Here is a comparison chart that shows nutrition facts of some of the most popular energy gels:

Name Calories Carbs Sugar Protein Sodium Potassium Caffeine
Hammer Gel 90 23g 2g trace 20mg 0mg 0mg/25mg/50mg
Gu 100 25g 5g 0g 50mg 40mg 0mg/25mg/50mg
Gu (Peanut Butter) 100 20g 5g 1g 65mg 60mg 0mg
Gu Roctane 100 25g 5g 1.7g 125mg 55mg 0mg/35mg
Clif Shot 100 24g 12g 0g 90mg 50mg 0mg/25mg/50mg/100mg
PowerBar Gel 110 27g 10g 0g 200mg 20mg 0mg/25mg/50mg
Accel Gel 100 20g 13g 5g 115mg 30mg 0mg/20mg

Happy running!