These days, there are endless options for athletes to choose from when it comes to the nutrition they can take during training and racing. There are gels, drinks, “chews,” honey sticks, and even waffles. It can get downright confusing trying to figure it all out.

As with training and racing, the rules for race-day fueling are going to vary widely depending on the athlete. Weight, temperature on race day, distance, and sweat rates all need to come into play when figuring it out. Even with using very specific calculations for each individual, however, much of it all comes down to trial and error.

So my first piece of advice to you is that on race day, no new is good new when it comes to nutrition. Practice definitely makes perfect for figuring out what your body can tolerate and in what quantities.

If you are training for a long event like a half or full marathon, you need to get into the habit of trying your nutrition out on your long runs. Carry, or set out at strategic places along your route, water or electrolyte replacement. Also bring along gels or chews or whatever type of carbohydrate supplement you’d like to try, and then have at it.

gels chewsI’d recommend trying different brands and flavors of all the types of supplements you are giving a go. Make note of how you feel with each: Did you cramp at all? Did you feel like you had water sloshing around in your stomach? Did you just plain old not like the taste of one flavor versus another? This is important, because believe me, at mile 20 in a marathon, if you are gagging trying to get your gel down, it won’t do you much good.

There are general rules of thumb in terms of quantity to ingest during endurance events. According to a 2009 position statement from the American College of Sports Medicine, for events longer than 60 minutes, consuming 0.7 g carbohydrates·kg-1 body weight·h-1 (approximately 30-60 g·h-1) has been shown unequivocally to extend endurance performance. Consuming carbohydrates during exercise is even more important in situations when athletes have not carbohydrate-loaded, not consumed pre-exercise meals, or restricted energy intake for weight loss. Carbohydrate intake should begin shortly after the onset of activity; [and continue] at 15- to 20-min intervals throughout the activity.

Even more recent research is pointing to the idea that more is more when it comes to carbohydrate ingestion. In other words, studies are showing that the more carbs you can tolerate in the middle of an event, the better your performance is likely to be.

sports drinkAgain, however, this is a very individual issue. Some people find that their stomachs are especially sensitive during long events. These people need to work around the rules and find something, in some quantity, which will work for them without stomach upset.

One combination that will usually cause upset for anyone is taking a gel and washing it down with a sports drink. That is sugar overload and very few people can tolerate that much at one time. Space out your gels and sports drink so that they are never hitting your stomach too closely together.

One final note—while you need to test out the various carbohydrate supplements in training, there can also be some value in doing some long runs on less fuel. When you overuse gels, you never give your body a chance to tap into its fat reserves for fuel. This is a topic for another article entirely, but do consider the occasional unfueled run once you have figured out what carbohydrate supplements do and don’t work for you.