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I’m in the Business of Building Glycogen, and Business is Good!

By Amanda Turner MS, RD, CSSD | June 7, 2016

Not only am I helping my fall endurance peeps, but I’ve jumped on the bandwagon myself! It’s been a long time goal of mine to run the Boston Marathon, and as you may know, that requires a pretty significant qualifying time. I attempted to qualify for Boston two years ago at the New Jersey Marathon, and I was absolutely crushing it for the first 20 miles. I was on pace, I wasn’t having any GI trouble (because I wasn’t eating much. . . more to come on that) and was feeling really strong until mile 20.5. . . . I. Hit. The. Wall. Hard. I literally couldn’t run and spent the next six miles walk/running until the finish line. As disappointed as I was that I didn’t qualify for that race, I was able to look back and learn a lot. Here’s what I learned:

1. I do a great job building glycogen stores. The fact that I could run for over 2.5 hours on minimal intake was a huge feat.

2. I sucked at taking in carb for that race. I made a poor, executive decision at the beginning of the race to change my whole nutrition plan and go minimalist style. I would never let my own athletes do that!!! With a history of GI distress at high intensity, I knew this would likely cause some discomfort, and my thought was to minimize what I ate to minimize discomfort. Because of this change, I didn’t supply enough glucose to my muscles to spare muscle glycogen along the course. I bonked at mile 20.5, and missed my BQ time by 7 minutes.

3. I sometimes make poor decisions when in highly stressed states. . .

Two years later, I’m ready to try again in my dietitian hat instead of my emotional athlete hat.

What is glycogen and why do we need it?
Glycogen is the storage form of carbohydrate in our skeletal muscles and liver. The purpose of having glycogen in the body is for times where we are fasting, if we have to make sudden movements (think fight or flight), or if we go on a long excursion without food (think tracking down a deer). We have about 500g of glycogen storage capacity for glycogen in the muscle, and this can be maximized based on training and nutrition regimens (below). Since glycogen storage is limited, we must eat during long endurance exercise in order to maintain that activity and avoid the “bonk” or “hitting the wall”.

How do we build glycogen stores?
Glycogen depleting exercise combined with the right recovery nutrition will help build glycogen stores. As we build, we can maintain activity at a higher intensity for a longer period of time. What is glycogen depleting exercise? This is exercise that significantly exhausts your muscle glycogen supplies. Think hard sprint repeats, a slow long run about 1.5-2 hours in length, or a tempo run with high intervals and short recovery bouts. These exercises leave your legs feeling “dead” and increase muscle sensitivity to insulin and thus, glucose uptake
to build glycogen.

The nutrition piece of this equation is carbohydrates. You’ll recover your glycogen stores regardless of whether you eat or not after a run. However, you’ll recover faster and become more efficient at recovery if you incorporate that meal or snack within an hour of your workout. This meal/snack must have carbohydrate in order to effectively promote gains in glycogen stores. Think of the following as good glycogen recovery snacks: oatmeal with milk, granola bars, bagel with cream cheese, pasta with chicken, or a fruit smoothie. While protein is important post-workout to recover the muscle, especially after a long run, carbohydrate is important to recover glycogen stores. As you get better at recovering glycogen post-workout, you should notice more spring in your step for the next day’s workout.