Staying hydrated and fueled during races is not as complicated as you might think.

Take one look around your work environment and it’s usually pretty easy to spot the runner in the room: water bottle within arm’s reach, banana and energy bar sitting atop her desk, and drawers so full of snacks you’d swear she was selling them to coworkers.

When in training, runners are always keeping a close eye on what, when and how much they’re putting into their bodies throughout the day. But when race day rolls around the questions inevitably start to surface. Did I eat enough for breakfast? Am I well hydrated? When should I pop my first gel pack? How often should I drink? Do I try a sports drink at Mile 12 or just stick to water?

The answers, of course, are going to vary by the athlete, but regardless of your ability level the last thing you want to be doing is doubting yourself on race day. You must toe the starting line feeling confident in your training, and it’s just as important to be sure of your fueling strategy as well.

Use the tips offered below to keep your gas tank full the next time you go the distance on race day.

Don’t Fear The Water

If you were to take an impromptu poll of 10 marathoners and ask them what they feared most on race day, it’s a safe bet that at least half of them are worried about dehydration. In races lasting over an hour, fluid loss should certainly be a concern, but it doesn’t have to be an extra source of stress if you can develop – and execute – a sound hydration strategy.

Before you even fill up your Fuel Belt bottles, however, it’s important to make sure you’ve hydrated well in the days before the event and have a plan in place prior to taking your first sip of fluid during the race. In her best-selling Sports Nutrition Guidebook, Third Edition, sports nutritionist Nancy Clark recommends that in the two to three hours before the starter’s gun goes off, runners should aim to consume 16-24 ounces of fluid in the form of water, sports drink or juice. This will ensure that you’ve topped off your tank prior to the event while giving your kidneys plenty of time to process fluids.

During longer races lasting over 90 minutes, Clark says to start drinking early and continue to drink often in an effort to stave off dehydration in the race’s latter stages. For some, consuming 6-8 ounces of water or sports drink every 20 minutes or so will do the trick, but for others that may be a bit much. The time to find out what works for you is during practice runs prior to race day. My own advice for the marathoners I coach is to take a few sips of something every 20 minutes for the first 60-100 minutes of the race and drink when they’re thirsty the rest of the way. Although rather unscientific, I’ve found through the trial and error of experience that this is an effective way to prevent fast fluid loss and avoid feelings of fullness late in the race.

Now that we know when to drink, the question becomes what to drink. Again, the answer will vary depending on the athlete. Some folks will do fine with just water, most others will need a little bit more than that. Over the course of a long-distance race you can be sure that you’ll sweat, losing not only water but also important electrolytes that are necessary to maintain muscle function.

While drinking water at regular intervals during your race will certainly go a long way in keeping you hydrated, to prevent cramping late in the race you may need to replace some of the electrolytes you lose through sweat. Scientists disagree about whether electrolyte depletion during exercise causes muscle cramps (there’s surprisingly little research investigating such a link), but many cramp-prone runners swear that taking in electrolytes helps them. The easiest way to do so is by taking some form of sports drink, which will contain a mix of electrolytes in the form of sodium chloride and potassium, as well as simple sugars that will help keep the muscles fueled.

If the sugary stuff doesn’t sit well in your stomach, however, there are plenty of other excellent options, including sugar-free, low-calorie electrolyte drink mixes, as well as electrolyte pills and salt tablets that, when combined with regular water intake, will keep your electrolyte levels up. If you don’t like the idea of straying too far from water or popping pills into your mouth, basic foods such as pretzels and bananas are chock full of everything you need to accomplish the same goal.

Top Off Your Gas Tank

On the topic of food, although you should never need to eat solid foods during a half marathon or marathon, some slower runners like to have the feeling of something a little more substantial in their stomach. Energy gels, “shots”, “blocks”, chews and beans are designed specifically for consumption during exercise and most provide roughly 100 calories of energy per serving, some electrolyte replacement and perhaps even a hint of caffeine for a late-race pick me up. Best taken and absorbed with a few sips of water, these products are easy to carry and are an effective means of obtaining energy and maintaining blood sugar levels.

So when should you eat this stuff? Clark recommends consuming 100 to 250 calories of carbohydrate per hour after the first hour during an endurance event to stay energized and maintain mental focus.

“By consuming carbohydrates during exercise, such as the sugar in sports drinks, your muscles have an added source of fuel,” Clark says in her book. “Because much of performance depends on mental stamina, you should maintain normal blood sugar levels to keep your brain fed and help you think clearly, concentrate well, and remain focused.”

Eat, drink, but be wary. Eating and drinking on the run shouldn’t be an excuse not to eat breakfast or hydrate before the race. Just as you wouldn’t start a long road trip on an empty gas tank, you shouldn’t start a long race on an empty stomach. The main objective of a fueling strategy is to stay hydrated and maintain energy levels throughout the race. Experiment with different foods and fluids during long training runs prior to race day and develop the confidence in a personalized plan that ensures you won’t run out of gas on when it’s time to go the distance.