Anyone who has wandered through their local Running Room store has run into the buffet of running fuels. The shelves hold a vast selection of gels, gummies, jelly beans, powders and so on. Between the different type of products, flavours, and brand options, even the most seasoned runner is left stumped about how to choose the fuel that's right for them.

The first step is to understand why it is necessary to fuel on the run, and when it is appropriate to do so. Running fuels are designed to enhance performance, yet overuse or misuse of these products can have negative consequences such as weight gain or an upset stomach. Use this guide to find the running fuel that is right for you.

What is the purpose of running fuel?

Carbohydrates are the body's primary fuel source during endurance activities such as long distance running, cycling, and triathlon. Glycogen is a stored form of carbohydrates in the liver that is used to fuel muscles during exercise. However, regardless of how many donuts or bowls of pasta you ate the night before your run, the storage capacity of the liver is limited.

The average body can store enough glycogen to fuel approximately 90 minutes of physical activity. Without carbohydrate intake beyond that point, an athlete will begin to experience symptoms such as feeling sluggish, heavy legs, and mental fog. This phenomenon is often referred to as "bonking" or "hitting the wall". Therefore, the purpose of running fuel is to provide a source of carbohydrates to the muscles during the activity, allowing the athlete to continue exercising and maintain peak performance.

When do you need to use running fuel?

Utilizing running fuel appropriately can significantly benefit athletic performance. But just because some is good, more is not necessarily better. Running fuel is made up of simple, easily digestible carbohydrate—in other words, sugar. Excess sugar intake, even in an active individual, can have a negative impact on overall health.

Supplementing with fuel is not necessary until the exercise duration exceeds 90 minutes. That means for most runners, it is not until training progresses to the half marathon and beyond that fuelling needs to be considered. It is, however, important to recognize that this is an average number that can vary widely individually based on genetics and intensity of exercise. There are runners who complete a half marathon with no fuel, while others find that a sports drink during a 10K race improves their performance

The timing of carbohydrate intake is also important. You wouldn't wait until your car completely runs out of gas before filling it up, and you should treat your body the same. If you will be running longer than 90 minutes, start fuelling around 45 minutes. A good general rule of thumb is to take in 30 grams of carbohydrates every 45 minutes.

What running fuel do I choose?

Running fuel products are specially formulated to contain 25 to 30 grams of easily digested carbohydrates per serving. It is important to take in water with running fuel because the concentrated sugars can cause stomach upset if not diluted.

Unfortunately, I can't give advice on the "best" running fuel, because there isn't one. The differences between gels, gummies, drinks, jelly beans and other products are based on personal tolerance, ease of use, storage considerations, and preference in taste and texture. Trial and error, though not entirely scientific, is one of the only ways to figure out what works best for your fuelling needs. I recommend testing new products on routes you are familiar with, in case you experience any stomach issues. As always, follow the cardinal rule of never trying anything new on race day. If the race hands out a fuel you are not used to running with, pocket it for a later trial but stick to your own familiar fuel for the race.

Race expos offer a great opportunity to try samples of different running fuel options. If you have a sensitive stomach, testing out a bunch of new fuels the day before your event is not recommended. Since most race expos are open to the public, you can also attend expos of events you are not racing in and sample the products.

What about using real food?

Using regular food as fuel can work equally well, though there are some factors to consider. Running fuel is portable, highly concentrated, easily digestible, and simple to consume. Finding a food that fits the same criteria is more challenging. Ideal food selections are high in carbohydrate but low in fibre and fat (which slow down digestion). Examples include dried fruit, boiled potatoes or sweet potatoes, pretzels, applesauce, and candy.

Learning to fuel endurance activities efficiently will have a significant impact on your overall performance. While there is science to suggest the appropriate amounts and timing to fuel, there is a lot of variability between individuals, thus trial and error is often required to learn what works best for your own body.