When runners move up in distances from 5 K to marathon and beyond, they have to start thinking about nutrition in a way that may seem foreign. To further complicate the issue, a simple Google search will yield a Golden Coral Buffet’s worth of ideas on what to use for fuel and technical instructions on how many carbohydrates are needed per hour based on the phase of the moon and the length of your mother-in-law’s toe nails. Certainly, for anyone who has mucked up their nutrition, getting the right amount of calories at the right time is very important, but it does not require a PhD in Biochemistry to get it right. But just in case it does, I’m here for the people.
There are lots of pieces to the nutrition puzzle, so in this first post we’ll discuss why the body needs nutrition at certain distances but not others. In part II we’ll talk turkey – what options exist for fueling? Finally, in part III, we’ll dive into the “soup to nuts” of eating on the run, as in when to eat and how to consume the nutrition to avoid the dreaded “gut bomb”.
Let’s dive into the mystery of nutrition. As I am a big believer in people taking ownership of their running experience, let’s discuss why nutrition is needed, particularly as the miles pile up. When you are performing in an endurance sport like running, you use two main forms of energy, carbohydrates and fat. Carbs are the easiest and most readily available to the muscles, while fat takes longer to serve up. Now add to that fact, the body can only store a limited amount of carbs “ready to use” in our muscles. This form of carbs is called glycogen. Science tells us our bodies can store about 90 minutes worth of glycogen in our muscles. So . . . what happens after that? Well, things can get a bit messy when our muscles run out of glycogen and we don’t supply more carbs. We won’t becoming raging zombies, but we will “bonk” or begin to see a drop in physical performance and mental focus (remember our brain uses a lot of carbs in the form of glucose).
Runner’s often talk about carb loading the night and/or days before a big race. Here’s the reason: Runners want to top off the glycogen in their muscles. By race morning, we want our muscles completely full with glycogen so that we can go faster and farther before needing to tap into other energy sources which are less efficient. So how much do you need to carb load? Again, we go to the science. Women are less responsive to carb loading than men of equal weight, so we need roughly 8 g/kg of body weight, the day before the race or long run. Guys, you can get the same effect with a bit less – sorry, you can skip the extra doughnut. So for those of us who don’t work in kg, that equates to approximately 3.6 grams of carb/pound of body weight (if I did my math right). For a 150 pound woman, this equates to 540 g of carbs the day before the race. That’s quite a bit of carbs. To put things in perspective, a banana is 27 g of carbs, 1 slice of 14 inch, regular crust pizza is 36 g, and a single pancake, 6 inches across is 22 g of carbs. If eating this many carbs is a big jump from your norm, definitely try a bit of carb loading before training runs of 14+ miles. You want to know how your stomach will react to a bolus of carbs on a long run and not on race morning.
So now you understand why runners carb load and how carbs can effect performance. The last piece of the puzzle is nutrition on the run. Energy sources designed for runners such as, chews, GUs, sports drinks, etc are formulated to be digested rapidly and used quickly by the body. That being said, anything we eat/drink on the run still has to be absorbed into the intestines, passed into the blood stream, and shuttled off to the muscles. This explains why runners want to maximize glycogen because it’s already at the muscles and ready to use and why it’s so important for runners to time their nutrition during a run. If you wait too long to take in energy, you will use up your glycogen before the new carbs come to town and . . . “bonk”.
Stay tuned for the next post where we will sidle up to the runner’s buffet to sample the options.