Gels 101

If you look back on all your training days or maybe even specific races, surely there was a time you experienced the dreaded “bonk”. You felt great and as time passed, suddenly you were deeper than no longer having gas in the tank. You quite literally had no more energy to give. If you’re lucky, maybe you’re just having to slow the pace down more than you’d like. However, in worst cases, you may start to stumble and find it difficult to walk or even think clearly.

I’d like to believe today, the worlds of running and fueling science are blending together more than ever. Understanding physiology and nutrition to improve performance is at an all-time high, as the sport of running — both on the road and on trails — grows exponentially. So what is a gel and what does it have to do with me bonking?

In simple terms, a gel is sugar! The main ingredients found in a gel include glucose and fructose; both simple sugars absorbed quickly by the bloodstream and used as energy. It’s important to know that when exercising the body’s main source of energy is glucose and glycogen (the stored form of glucose in the liver and muscles). Your body contains a finite amount of glycogen and as you continue exercising, you begin to deplete those stores. This is when you risk the bonk. With glycogen depletion comes fatigue both physically and cognitively. The body can no longer keep up with the energy demands as it has to switch over to a slower energy producing system (known as fat oxidation). Therefore, the purpose of taking a gel would be to keep glucose circulating within the bloodstream and delay the depletion of glycogen.

Now comes the hard part. Which brand do I choose? What flavor? Caffeinated? Unfortunately the answer to all of those questions is that it’s highly individualized. If you are completely new to using gels while running, I recommend picking out a few different brands and within those a couple different flavors. You may find a brand you like but within that brand there may be flavors you try and completely don’t agree with. Another important note is that if your digestive system isn’t used to fueling while running, the first few (or handful) of times may not go seamlessly. Don’t give up! It doesn’t mean your stomach can’t handle “taking gels”, it takes time for your body to get used to breaking down new carbs while maintaining all other systems as you run. 

This brings us to more specifics on different brands of gels and why it’s worth trying several out. As you go through this fueling journey you will soon learn that consistency or thickness is often the trait that makes or breaks if someone tolerates a gel or not. The “Gu” brand is generally known to be the thickest out there, and are recommended to be taken with 4-6oz of water (if you read the fine print) because they are non-isotonic. While the “Gu” brand has more flavors than other brands, their thick consistency can make it difficult to consume in many cases. On the flip side there are brands offering “isotonic” gels, meaning they are pre-mixed with water and much easier to consume and absorb into the bloodstream. Popular brands (to name a few) include: Precision Fuel, Never Second, Science in Sport (SiS), and Maurten. As an ultra trail runner that takes in 90-110g per hour in 50K races - I can personally tell you that none of these brands have the same consistency or flavor! It truly will be in your best interest to try a brand and see what works best for you.

Wait, did that say 90-110g per hour?... How much should I be taking?... perhaps the second hard part: deciphering how many grams to consume per hour and when it’s more imperative to aim higher. While still a highly individualized concept, there are at least more scientific parameters to help guide you than there are for choosing a flavor! The general rule of thumb is any run over 1 hour, you’ll want to supplement with 30-60g. *The average gel is 22-24g of carb, however there are nutrition brands selling larger gels with a higher carb content* What if you’re trail running around an hour but you’re climbing a ton? What if you're racing a fast road marathon? Or it’s a workout day and you’re doing intervals with rest in between?  Are the carb needs the same? Not at all:) This topic could probably be a blog in itself (and maybe it will!) but for now understand that fueling needs are ever-changing and have several determinants. Prioritize fueling in long runs no matter what pace you run and remember that the higher the work rate within the workout/run - the higher the fueling demand. 

Current google search results for “how many carbs should I take when running” are pretty outdated. Cyclists and ultra runners are leading this sort of scientific “high carb” revolution. Throughout the 90s and even the majority of the 2000s, it was believed that the body could only absorb 60g of carb per hour. Today you can find cyclists and runners utilizing up to 140g (maybe more) of carb per hour. A lot of this is accredited to advancements in sport research and sport nutrition companies creating hydrogels with precise glucose:fructose ratios to prevent GI distress. This topic could probably be a blog in itself (and maybe it will!) but for now understand that fueling needs are ever-changing and have several determinants. As you get used to fueling you can increase your carbs per hour, which would provide more immediate energy to the working muscles = power, speed, endurance performance increases. 

Final thoughts: Fuel early and fuel often! Rather than stoking the fire, higher fueling rates keep the fire burning. Always take in your carb before you start to feel tired, hungry, or sluggish. Waiting until the last minute to fuel won’t save you. It’s best to come up with at least a loose plan when you’ll take in carb (i.e. one in after the first 30 minutes, one after the third interval, etc.). For trail running, a great time to take in a gel is when you find yourself climbing or at a slower section. A workout with rest intervals provides great opportunity to quickly get some fuel while the stomach isn’t jostling. But many times you will need to take one while you’re running at pace, so practice fueling during different types of runs you do throughout the week. Whether it be a slow easy run, tempo, or long run - the only way to train your gut to handle fuel coming in is to put it in different scenarios to do so. If you’re just starting with fueling runs, be patient and try out different products until you find a brand you love. Better to interrupt a training session with carb mishaps than a race! 

I hope this article gives you a good starting place or the confidence to introduce gels into your training. Happy running and happy fueling! :)