When I started training for this race, I knew that hydration and fueling are important but I had no idea what a glycogen depletion run was or that I was doing them every week. I hadn’t really thought much about whether or not I ate before my runs because I didn’t like to. But when I ran across an article on Pinterest about glycogen depletion runs and marathon training, I decided to read it, and I’m so glad I did!
A glycogen depletion run is simply a run you don’t fuel for. You don’t eat before, and you don’t eat during. You only hydrate. I had done this for most of my races simply because it was easiest. Plus, I don’t like eating early in the morning, which is when I do long runs. This is a great thing to do early in training, because you teach your body to burn fat rather than relying on stored carbs. When you don’t eat before a run and don’t fuel during a run, your body has no carb store to draw from and it burns fat.
However, when you are training for a marathon, that won’t work. That’s because the marathon distance is longer than anybody can store glycogen for. So, you need to not only carb-load, but also fuel during your race with a sports drink and a gel or chew. You have to practice this during training runs for a bunch of reasons.
First, it’s just physically hard to manage if you aren’t used to eating or drinking while running. You can choke, you can get too much air in your stomach, or you might get indigestion. Second, you need to figure out what kinds of fuel work for you. There are many different gels and chews out there to choose from, and they vary from texture to taste to sweetness. I don’t know any two runners who prefer the same thing. Third, you have to teach your body how to make metabolic bandwidth for digesting while you’re on the go. The reason you never eat a big meal and then go run is because once you start running, your body diverts all your metabolic efforts toward running. While running a long distance, your body needs to learn how to divert some of that energy back for digesting so you can get extra fuel. If you don’t, then you run through all your fuel in a strange process called “bonking.” Bonking happens when you run through your glycogen stores and literally run out of energy. Your body just stops working. Although you remain conscious, you can no longer keep going. It’s kind of like when your car runs out of gas—the lights still come on, but you’re not going anywhere. If you’ve ever seen this happen in real life, the person just kind of looks like a machine that starts to fall apart mid-stride.
So how do you avoid bonking? You fuel before you need it. In most races, I would not drink or eat until I felt like I needed it, but after reading the articles about glycogen depletion, I realized that was completely the wrong strategy. Once I need it, it’s too late, because my body can’t digest it for use that fast, so my new strategy is “eating before needing.”
First, I have started carb-loading before my weekly long runs. This just means eating carb-heavy meals the night before. These runs have consistently been more than 13 miles for a few weeks now, and now I am coming up to 16 miles, so I think it’s appropriate. I also have tea with honey before bed for an extra boost. This is an addition to hydrating starting two days before my run—the goal is clear pee by the night before a long run.
Second, I eat a Clif bar or bagel before my run, and I take my recovery vitamins then, too. They are liquid, so that gives me a little extra hydration as well. Third, I take sports drink and some shot blocks with me on my run, usually three of them, and I make sure it’s all gone before I am three miles from the end. I divide my run up into even parts so I know when to take the blocks, and I try to take a sip at least each mile.
The week before I tried it, one of the girls in my long run group had mentioned how quiet I had been during the run that day, and after, too. I just hadn’t felt like talking, and afterward I felt completely depleted, so much that conversation felt like an effort. The next week, I was chatty and peppy throughout the run and was able to chat during coffee afterwards like I hadn’t gone running at all. I ran the same pace both times, so this isn’t about increasing speed, but your performance and how enjoyable the run is. Having that extra energy makes a huge difference!
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