In 1968 when Amby Burfoot won the Boston Marathon, he did not drink a single drop of water on the course. Back then, this was not even unusual. Like most other marathons at the time, Boston did not offer water stops; most runners believed that they would become “waterlogged” and that quenching their thirst would only weigh them down on their way to the finish line. Today, we know better. Consuming water and sports beverages has become an essential part of maintaining speed and avoiding dehydration. However, drinking too many liquids can be harmful, leading to hyponatremia, or low blood sodium, which most commonly occurs from drinking too much liquid before, during, or after a race.

An immense amount of training is involved in preparing for a marathon, so don’t let improper marathon hydration negatively impact your efforts. By following these tips and staying conscious of your hydration level, you’ll be ahead of the pack on race day.

Develop a Plan

Your body is unique, so don’t copy what other runners are doing during the marathon. Some runners will need less fuel than you, others more, but by developing a plan prior to the big day, you can adequately hydrate your body and avoid running out of steam early on.

On average, a runner will lose 2-3 pounds of fluids during a marathon. To avoid dehydration or hyponatremia, you’ll want to strive to replenish as much as you have lost. The best way to determine how much fluid you need is to calculate your sweat rate. The Beverage Institute has a great guide to help you determine your sweat rate on your next outdoor run.

Stay Hydrated During the Race

Hydration stations are great tools to use during a marathon. Depending on your size, your stomach can empty out about 6 to 12 ounces of fluid every 15 to 20 minutes. Therefore, a good general guideline for runners is to drink between 3 and 6 ounces of fluid every 15 to 20 minutes. In practical terms, this means you’ll want to grab a cup of water about every other mile. For reference, a big gulp of water equals about one ounce. If you are hydrated before the race, you can skip the first station, just be sure to refuel within the first 45 minutes of the race.

Supplement with Sports Drinks and Gels

The ideal outdoor temperature for a marathon is in the mid-50s, but of course conditions are never guaranteed to be ideal. If the temperature rises into the 70s or 80s, your body will require more fluids to replenish those lost through sweat. Sports drinks and gels are both great ways to help you retain your fluids. The carbohydrates in these products will help you restock your energy supply, and the electrolytes that most of them contain replace those you lose when you sweat, which will help you avoid hyponatremia.

Don’t Over do It

Everyone wants to start their marathon off on the right foot. Begin your race well hydrated to maximize your performance and start the race strong, but don’t overhydrate. Avoid drinking water during the hour before the race begins. UCSF Medical Center recommends drinking about 16 ounces of water or sports drink exactly two hours before the run starts. That way, by the time the marathon begins, your body will have absorbed the fluids into your system.

Keep Recovery In Mind

A marathon is one of the most high-endurance physical activities you can attempt. Pushing your body to the limits makes refueling after the race critical. Within a hour of completing the race, eat or drink 200 to 300 calories of carbohydrates and a bit of protein to refuel and repair your muscles. According to the Boston Athletic Association, hyponatremia can also occur by drinking too many fluids after the race, so remember to rehydrate slowly and with fluids containing electrolytes. This will ensure that you will recover properly after you’ve crossed the finish line.

Practicing proper marathon hydration habits is a significant component of your success on race day. Before you begin, have a plan to care for your body throughout the race by drinking an adequate amount of fluids to ensure your safety, maximize your performance, and make all of your hard work pay off on the big day.