A few weeks ago I had my first test of the semester (guhhhh), and it was appropriately on anything and everything carbohydrates, including metabolism and use during physical activities like running. Since I’ve brushed up on the details of carbohydrate fueling before, during and after running, I thought I’d share some key learnings.
So here are the basics, broken down.
Glycogen is the body’s storage form of glucose, which is mainly what we use for energy when we run.
Our muscles only have a limited amount stored away (about 300 grams), and our liver stores about 100 grams. As we run, we break down our glycogen stores and use them for energy to keep us going.
Before a run
It’s important to get some fuel into your body before you start a run – especially if it’s a longer run. The American College of Sports Medicine recommends 1-4.5 grams of carbohydrate per kilogram of your body weight (one pound is about 2.2 kg) between 1-4 hours before a run or race.
What does this look like? For a 125 lb female: 2 grams x 56.8 kg = 113 grams carbohydrates. This could be a big bowl of cereal or oatmeal with fruit or a bagel with peanut butter with a piece of fruit.
The ACSM also recommends taking in some more carbs about 30 minutes before a race or event. I usually eat a banana right before running or racing because it agrees with my stomach and gives me a little extra energy.
During a run
Glycogen stores are dramatically reduced after 1-2 hours of running, and they need to be repleted or our energy levels will plummet. This is why a lot of runners take in some Gatorade or gels during longer runs. We use approximately one gram of glycogen per minute during moderately intense exercise, and there’s only so much to go around!
The standard recommendation from the American College of Sports Medicine is to take in 30-60 grams of glucose per hour to keep our energy constant. Glucose is the simplest form of carbohydrate, and your body can quickly use it for energy (think sugary Gatorade!).
Replenishing glycogen stores before they’re totally depleted is key, or else it’s much harder for your body to use new glucose for energy (and you hit the dreaded “wall“).
After a run
It’s super important to replenish our glycogen stores with carbohydrates immediately following a run – our muscles are working overtime to rebuild glycogen and we need to take advantage of this! The ACSM recommends consuming 1.0–1.5 grams carbohydrates per kg body weight within 30 minutes of finishing a run, and then again at 2–hour intervals for up to 4–6 hours.
Consuming some protein right after a run is just as important to help rebuild damaged muscle tissue.
The ideal ratio of carbs to protein for post-run refueling is 4:1 (though some studies have found 3:1 is best) – my favorite example of this ratio is chocolate or strawberry milk.
My stomach can be iffy after long runs, but it’s usually pretty easy to get this stuff down quickly.
Despite these recommendations, we runners know that fueling during a longer run is highly individualized – what works for one doesn’t necessarily work for all.
What works for me
I prefer to take watered down Gatorade with me on runs longer than 15-16 miles, and add a gel for runs longer than 18 miles. During a race like a marathon, I’ll sip on Gatorade or water throughout the race when I need it and take two gels – one around mile 10 and one around mile 20 because I need the extra energy.
Here’s what a long run fueling plan looks like for me for a usual 15-16 miler
Pre-run – banana with a dollup of peanut butter.
If I have a race, I’ll wake up a bit earlier and eat a more substantial breakfast beforehand, usually some toast with peanut butter and jam.
During the run – watered down Gatorade (vanilla PowerGel for runs 18 miles and up)
Post-run, pre-shower – more Gatorade and a scoop of peanut butter
Post-run, post-shower – cereal or toast with peanut butter and berries
And then I just make sure to keep on refueling throughout the day with nutrient-dense foods.
So there you have it – there’s so much to learn about the body’s intricate system and how it uses carbohydrates, I find it pretty fascinating (and yeah, I guess I’m a science geek!).
For a lot of runners, fueling is a constant experiment in figuring out what specific formula works for them, but I hope these details help explain the bigger picture and maybe even help you have a great long run or race this weekend 🙂
Question: Have you mastered your pre, during and post-run fueling plan? What works (or doesn’t work) for you?