If you’re running a marathon this year, you probably should be training with Gatorade Endurance Formula. Bear with us; we're not shilling for the product here, but instead trying to save you from the most painful, long, stomach-churning race day of your life. Yes, drinking sports drink without training can, to put it kindly, cause gastrointestinal distress on race day. That's why one of the most important — and overlooked — parts of marathon or any endurance training is knowing what to do with the sports drink that's on the course. For 300 races — including the New York, Boson, Chicago, and Rock & Roll marathons — that is Gatorade Endurance Formula. So whether you like it or not, it’s time to embrace the stuff.
In light of Gatorade having clearly cornered the market, we reached out to Matt Pahnke, a scientist at the Gatorade Sports Institute who works directly with athletes training for marathons and triathlons and asked him how, exactly, we should fuel up during the race and what we can do to train for it. His answers were direct and based on lab research — so get our your calculator and get ready to follow along.
Step 1: How Much Do You Sweat?
“First thing, test your sweat rate,” says Pahnke. To do this do a warm-up (10 to 15 minutes), weigh yourself, and then go for 60-minute run at whatever intensity and — this is key — temperature you will be experiencing on race day. Don’t drink anything during the run. Go home and take your weight.
Then, you can enter all this data into the fluid loss calculator (here’s Gatorade’s official calculator; be sure to enter 0 for the fluid volume before and after, assuming you drink nothing during the process)
This is the total volume of fluids that you lose. You don’t have to match it during the run — i.e. filling up every ounce of water you lose — but you shouldn’t lose more than 2% of your fluid. So aim to drink nearly as much as you lose.
The Sweat Rate Calculation:
Say your weight is 168.0 pounds after a warm up and you end up at 166.5 after an hour run at marathon pace without drinking anything right before or during the run. That's going to be about 23.0 ounces per hour. If your marathon pace is 6:52 that means you'll need 3 hours worth of fluid, or 69 ounces (3 hours x 23 ounces). Divide that by 26 miles (most coaches say you should drink at each fluid station) and that's about 3 ounces of fluid needed per station (more on how to calculate that in Step 3).
Step 2: How Much Fuel (Carbs) do you Need?
Now that you have the water weight down, you need to know how many carbs you need. This is where the sports drink comes in. The usual recommendation for carb intake for performance is 30 to 60 grams of carb per hour. Once you go beyond two hours, you want to get as much as your can handle — with a hard stop at 90 grams per hour (studies show this is about as much as any athlete can take in one session).
How do you know how much you can handle? There's one way: by imbibing sports drink during a long training run. Start on the lower end — with 30 grams on a 60 minute run (12 ounces of Gatorade Endurance Formula has 23, so you can do the math there). “If you feel ok, your stomach is good, bump it up and find your personal limit,” says Pahnke.
The Carb Calculation:
Let's assume your body can handle 60 grams of carbs per hour during exercise without getting an upset stomach and that your sweat rate was, as calculated above, 69 ounces for the three-hour race. One ounce of Gatorade Endurance Formula contains just 1.75g of carbs. That means that 34 of your 69 ounces of fluid should include Gatorade Endurance Formula. Since you're drinking a little less than three ounces of fluid at a station (69 ounces / 26 stations), you should drink Gatorade Endurance Formula instead of water at 11 of these stations (34 ounces of Gatorade / 3 ounces per station) — nearly half.
Step 3: Take It to the Race Course
Here’s the trickiest step. Assuming you don’t want to carry bottles of Gatorade or water with you (you don’t), you’re going to need to figure a way to calculate your intake. There are two ways to do this:
The Course Calculation:
1. Eye the cup. If you’re a crackshot at guessing the liquid in a plastic cup, go for that. A typical course cup might hold 8 ounces of water — so given the calculations above, you're looking to drink a little less than half a cup per station.
2. Go by feel. The other way takes practice. Measure out the amount of water you need to drink at each station. Pour that into a cup and let it sit in your mouth. Feel that weight on your tongue? How much it fills your cheeks? Take note and then swallow. Do it again. Now, practice in reverse: Drink what you think is the right amount of water from a filled paper cup and spit that out into your measuring cup. Repeat every day until you can measure it by feel.
Step 4: Choosing a Flavor
This one is easy. Running the New York Marathon? Drink Lemon Lime. Don’t know what’s on your race course that day? Ask.