In training for my first marathon, I made a variety of fueling experiment errors. These included not hydrating enough (in amount or frequency), trying to go too long without calories and neglecting to notice which meals worked well for me before a weekend long run. I also trained during the winter for what ended up being a toasty spring marathon day in March, so most of what I had practiced seemed insufficient anyway!

Race-day fueling strategies can be a major source of stress for runners at every level. Identifying what works for you takes some trial and error, and although those “error” days are tough to weather they are helpful in determining what works in subsequent races. Practicing early and often with your fueling strategy is one way to boost confidence, and energy levels, on your goal race day.

Race-day fueling strategy factors

As you outline your race-day fueling strategy experiments throughout your training cycle, consider all of the following factors:

Race-day start time
Some of the major marathons, such as New York City and Boston, have later starting times due to race-day logistics, so you’ll need to plan accordingly as your pre-race breakfast will need to be supplemented without additional calories and fluid before you get to the starting line.

Race distance
Training for a distance that’s new to you may present unique challenges, as will changes in seasonal weather patterns.

Seasonal race-day weather (or what may be expected)
Most marathon training cycles span 14 to 16 weeks and bring a change of season along with them.

What your gut is used to
If you’re gut isn’t used to eating during activity, training your digestive system may be as important as training your cardio and muscular systems.

Sports nutrition guidelines recommend consuming 30 to 60 grams of carbohydrate per hour of exercise, along with approximately 8 ounces of water. This is a big caloric range—120 to 240 calories from carbohydrates! Your needs will vary based on weight, height, fitness and intensity of your effort. Aim for high-carbohydrate, low-protein and low-fat foods and sport products for fueling during the run.

Personal food and taste preferences, in addition to the fuel and hydration options provided on the course (if any)

Last but not least, consider what actually tastes and feels good to you as you experiment with different fueling options. Then, think about fuel that will be provided on the race course (e.g. gels, and random snacks provided by spectators!) when you decide which fuel products or foods to experiment with.

Optimal Race-Day Execution

With those things in mind, try these three steps to practicing your race-day fueling strategy to help you cross the finish line:

1. Train your gut early and often!

Even as a seasoned marathoner, I start bringing fuel with me on long runs early in the training cycle. It’s helpful to introduce some routine to the gut along with the muscles. This includes eating before long weekend runs, even if the early weekend runs aren’t yet “long” by personal standards. Then practicing fueling while in motion. More on that below.

Remember the fueling guidelines—30 to 60g of carbs per hour of exercise—and start on the lower end of that range to train your gut. Example: One serving of CLIF Shot BLOKS (3 BLOKS) provide 24g of carbohydrates (and 100 calories). Some sport drink mixes provide fluid, electrolytes, and carbohydrates. Others only provide water and electrolytes (e.g. Nuun). Factor this into your total intake throughout the hour(s).

The key: Work with your digestive system to adapt to fuel and hydration before and during exercise. Start doing this in the first week of your training cycle, to avoid experiencing issues later during peak weeks!

READ MORE: How to Replace Electrolytes With Real Foods

2. Fuel during a variety of workouts.

Some training cycles suggest doing every long run at a “slow” pace or easy effort. This may mean that your fueling practice always happens during a relatively low-intensity workout, which probably doesn’t mimic race-day adrenaline or goal race paces. To account for this, introduce fueling practice to a variety of your workouts. Bring fuel on a tempo run and eat in the middle of the tempo interval. Carry a handheld water bottle or hydration pack during track workouts to get used to the feel and weight of it. Test out new fueling products or foods while on a short run, so if it doesn’t sit well, you haven’t sacked an important weekend long run.

The key: Get creative with your fueling practice and test things out during a variety of workouts! Stick to what works best during your long runs or speed workouts, depending on your primary race-day goal.

2. Take detailed fueling notes during training and racing.

I learned a lot about my marathon fueling needs and preferences on that first marathon race day—much more so than during the whole training cycle itself. I’ve learned lessons from different seasonal races, course variables, trail running, and even high-altitude needs. Taking notes right after a workout that included fueling practice (which could be easy runs, speed work or long runs, as mentioned above) and after races is helpful!

The key: Details! Note how often you fuel (e.g. “every 35-40 minutes”), what you ate or drank, how much you brought with you versus how much you consumed (e.g. “carried 20 ounces but had some left”), what tasted good, and what you had to eat before you got started. The more detail the better, as you hone in on your race day fueling strategy and decide what works best for you!

If you find something that works well for one race or one training run, consider it a big success! But don’t stop there. I’m a big advocate for variety. Keep experimenting and finding other options that work for you. Test out the fuel and hydration options that will be provided at aid stations, and others that you can easily bring and carry yourself. And don’t shy away from pre-race meal variety, in case you travel or don’t have certain things available for whatever reason. Allow yourself to be flexible with your race day fueling strategies, and test them often to increase your chances of race day success.

READ MORE: Ignore These Food Rules and Run Better