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Marathon race-day nutrition and hydration

This is an excerpt from Advanced Marathoning-4th Edition by Pete D Pfitzinger,Scott M Douglas.

So you’ve followed the advice in this chapter by eating properly and staying well hydrated throughout your months of preparation. Guess what? Your work isn’t done yet. Your strategies for taking calories and fluids on race day can have a strong influence on your marathon performance.

Let’s assume you’ve done a good job of glycogen loading during the previous several days and you’re well hydrated. Before the race, you want to take in between 300 and 500 calories of mostly carbohydrate to top off your glycogen stores. It’s best to ingest these calories 3 to 4 hours before the race. This shouldn’t be a big deal for races with late starts, such as New York City or Boston, but for a race such as Chicago, which starts at 7:30 a.m., or Honolulu, which starts at 5:00 a.m. (!), you may have to get up a bit on the early side, eat something, and then try to doze a while longer. (Good luck with that on race morning!) You should also take in about a pint (0.5 L) of fluid to replace fluids lost overnight and ensure that you’re fully hydrated.

Even if you carefully carbohydrate load for several days leading up to the marathon, you don’t have much of a buffer against glycogen depletion. The solution is to take in additional calories during the race.

How much you need to drink during the marathon depends on your body size, the heat and humidity, and your sweat rate. The target is to replace the fluid you lose from sweating so you do not lose more than about 3 percent of your body weight during the marathon. As we will see later, that is a challenging target to achieve, particularly on a warm day. The maximum amount you should drink during running is the amount that can empty from your stomach or the amount required to avoid excessive dehydration from sweat loss, whichever is less. Drinking more than you have lost brings the risk of hyponatremia, which is discussed later in this chapter.

Research has shown that runners’ stomachs can typically empty only about 6 to 7 ounces (177-207 mL) of fluid every 15 minutes during running, representing about 24 to 28 ounces (710-828 mL) per hour. If you drink more than that, the extra fluid will just slosh around in your stomach and not provide any additional benefit. You may be able to handle more or less than the average, however, so experiment with how much liquid your stomach will tolerate.

During training, it’s relatively easy to stop and drink as much as you want whenever you feel like it. All that’s required is a bit of planning and perhaps a few containers strategically placed before your long run. During the marathon, however, it’s very difficult to drink 6 to 7 ounces (177-207 mL) of fluid at an aid station without stopping. Marathoners who run through the aid stations often take in only a few ounces of fluid.

For serious marathoners going for a personal best time, if you drink 4 ounces (118 mL) at 10 drink stops during your marathon, you will have done a typical job of hydrating. What does taking in 40 ounces (1.18 L) of fluid during the marathon mean in practice? If you run the marathon in 3 hours and are losing 3 pounds (1.4 kg) per hour, you will lose 9 pounds of fluid (4.1 kg) and take in 2.6 pounds (1.2 kg), for a net loss of 6.4 pounds (2.9 kg). If you weigh 150 pounds (68 kg), you will have lost 4.3 percent of your body weight; this will likely contribute to slowing moderately late in the race.

Drinking 40 ounces (1.183 L) of an 8 percent solution will supply 95 grams of carbohydrate. Each gram of carbohydrate contains 4.1 calories, so you’ll be taking in about 390 calories during the race.

A complementary method of taking in carbohydrate during the marathon or your long runs is to use energy gels. Depending on the brand you choose, each gel packet typically contains between 80 and 120 calories of carbohydrate. You should follow most gels with a couple of sips of fluid to wash them down, and you should take in approximately 4 to 6 ounces (118-177 mL) of water afterward to help absorb the gel. Some gels, however, are isotonic (check the label), so you do not need to take in fluid to help with absorption. The best time to take an energy gel that is not isotonic is shortly before an aid station.

As always, don’t wait until race day to try an energy gel because it takes practice to get the water intake right and to feel comfortable running after taking a gel. You should develop a plan for taking in sports drinks and gels during your marathon. The makeup of your personal plan will depend on how warm and humid your marathon is likely to be, how much carbohydrate you intend to take in during the race, what types of carbohydrate you are most comfortable taking while running, and what options are provided by the race. A typical plan for a sub-3-hour marathoner would be to drink 40 ounces (1,183 mL) of a sports drink with 8 percent carbohydrates, divided between 10 aid stations, and to take gels providing 100 calories of carbohydrates each at about 40 minutes, 80 minutes, and 2 hours into the marathon. This plan would supply 690 calories of carbohydrates. During the marathon, a 140-pound (64 kg) runner typically burns about 100 calories per mile. Of those 100 calories, about 80 are supplied by carbohydrate. This plan, therefore, supplies enough carbohydrate fuel to last an extra 8 miles (12-13 km) and substantially boosts your likelihood of reaching the finish line without running critically low on glycogen. Slower marathoners can further boost their carbohydrate intake by taking another gel after about 2 hours and 40 minutes (and after 3 hours and 20 minutes if you’re still going).

There is evidence that just rinsing your mouth with a carbohydrate drink can enhance performance (Burke and Maughan 2015). The mechanism seems to be that receptors in the mouth sense the carbohydrate and signal reward centers in the brain. You can use this strategy as a boost in the last 10 minutes of the marathon when it is too late for carbs to be absorbed in your intestines.

Avoiding Hyponatremia

If you run the marathon in more than 3 hours on a warm day and drink large amounts of plain water during the race, you are at risk of hyponatremia. This is a condition caused by unusually low sodium levels in your blood; a large proportion of your body fluid is replaced with water, thereby reducing your body’s sodium content. There is evidence that women have a moderately higher risk of developing hyponatremia than do men. The symptoms of hyponatremia include weakness, nausea, disorientation, bloating, dizziness, and in extreme cases, seizures and coma. Hyponatremia typically occurs only toward the end of ultramarathons or Ironman triathlons, but it can occur in the marathon on warm days, especially for 4-hour-plus marathoners who consume only water. The simple way to avoid hyponatremia during a hot-weather marathon is to consume fluids containing at least 250 milligrams of sodium per liter and to not drink more than you have lost as sweat.

How to Drink on the Run

The race nutrition plan described above assumes you’re regularly taking in a good amount of fluid, as opposed to most of it spilling down your front. Practice drinking while running at close to marathon race pace until you get good at it. It makes sense to slow a bit at the aid stations, but if you’re competitive, you won’t want to lose time to the runners around you. By practicing drinking on the run, you can greatly improve your proficiency at this skill.

If you’re an elite runner, you can usually arrange to have squeeze bottles at the aid stations along the course. This is optimal but obviously not readily available to everyone. Non-elites can help themselves by choosing marathons where friends or family members can meet them regularly along the way and give them bottles. A growing number of competitive marathoners also take advantage of small, flexible bottles that conform to your grip and can be carried for several miles without significantly affecting your arm carriage.

Still, the majority of marathoners must master the paper cup. A convenient way to practice drinking from cups is the round-and-round-the-track method—simply set up some cups at the local track and practice drinking every couple of laps. The advantage of the track is convenience. The disadvantage is that, if you’re running intervals, you’ll be breathing so hard that you’ll get to experience the dubious thrill of getting water up your nose. This approach works really well during a tempo run. If you do a 20- to 30-minute tempo run on the track and take a drink every two to three laps, you will quickly improve your drinking-while-running technique.

Race-Day Technique

If volunteers are handing out fluids during the race, try to make eye contact with one and point at the cup so that you don’t surprise them. (If the cups are on a table, eye contact with the cup generally won’t help.) If volunteers are offering both water and a sports drink, call out your preference as you approach the aid station so that the right volunteer hands you a cup.

Slow slightly and try to move your arm back while you grab the cup so that you don’t hit the cup with your full running speed. Squeeze the top of the cup closed so that all of the liquid doesn’t slosh out, and take a swig. This will help prevent fluid from going up your nose when you tip the cup up to drink. The trick is to breathe normally. Always take a couple of normal breaths between swigs. When you’re done drinking, accelerate back to race pace.

Unless you’re an elite marathoner, the best strategy on a warm and humid day is most likely to stop and drink at the aid stations. Marathons typically offer aid stations about every two miles, although some larger races have up to 20 stops. Let’s say that, from the start, you stop to drink every 2 miles. That’s 12 stops between the start and finish. If you spend 10 seconds drinking at each stop, you’ll add 2 minutes to your time. If you run through the stops while drinking, you’ll slow a little anyway, so stopping isn’t going to add much time, and stopping helps ensure that you take in enough fluid to fight off dehydration. On a warm day, an extra 2 minutes at the water stations can repay you with 10 to 20 minutes gained by the finish of the marathon.

What and when you eat and drink play an important role in how you adapt to training for a marathon. As we’ve seen, neglecting proper nutrition and hydration will mean not reaping the full benefits of your hard work.

More Excerpts From Advanced Marathoning-4th Edition

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