article by Sam Bassetti
You may have heard your riding buddies mumbling something about replacing glycogen stores while stuffing their face with a personal-sized pizza post ride. So what is glycogen and why is it important? First, it’s important to understand the relationship between carbohydrates, glucose and glycogen:
Carbohydrates can also be referred to as saccharides, and are a group of organic molecules that includes sugars, starches and cellulose. They can be made up of multiple saccharide molecules linked together (polysaccharides), two saccharide molecules (disaccharides) or a single saccharide molecule (monosaccharide).
Monosaccharides and disaccharides can also be referred to as sugars. Glucose (blood sugar) is an important monosaccharide that provides energy for muscle contractions. Glucose is stored as a specific polysaccharide in our bodies called glycogen.
Many molecules of Glucose are chained together to form glycogen, which is stored in our muscles and liver. Glycogen is broken down into individual glucose molecules in muscle cells when needed for energy production.
Glycogen is essentially stored carbohydrate, and as we know carbohydrate as a substrate for endurance exercise is very important. Glycogen is mainly stored in our muscle fibers and liver and is readily available for use during exercise.
A few landmark early studies have set the stage for why glycogen is so important. These studies showed that:
These results have been backed up and confirmed by many related studies. It is clear that glycogen is important, and the amount of glycogen that you have is also important.
A normal, healthy 70 kg male eating a high carbohydrate diet might have around 600g (2,400 calories) of carbohydrate stored as glycogen in their muscles, plus another 90g in the liver. Compare this to about 10g of carbohydrate in the blood stream, and you can quickly see why glycogen is vital as a source of carbohydrate during exercise.
Glycogen Before Exercise
A high carbohydrate diet is key to maintaining and maximizing glycogen stores (5,6,7). This is pretty straightforward, in order to store carbohydrates, you need to first eat carbohydrates.
There are some slightly more complex strategies to maximizing your glycogen stores such as carbo-loading or carbohydrate periodization that involve altering your carbohydrate intake in specific ways, but a more simple strategy will be easier to follow.
The simplest strategy is to maintain a high carbohydrate diet that reflects the energy requirements of your training or racing. The blog posts, Are you Fueling Enough on the Bike? and 3 Strategies to get Lean and Stay Lean have more specific dietary recommendations.
Glycogen During Exercise
Once you start riding or racing, you will be using up your glycogen stores, especially during the first hour of exercise and during higher intensity efforts. You will not be replacing glycogen stores as you ride, but rather you will increasingly rely on blood glucose and free fatty acids in the later stages of a longer ride or race.
Again, see Are you Fueling Enough on the Bike? for detailed nutritional recommendations, but understand that once you have started exercising, the glycogen you started with is all you have to work with, additional carbohydrate needs will need to be met with on-the-bike nutrition.
Glycogen After Exercise
Replacing glycogen stores should be one of your main concerns immediately post ride or race:
In order to ensure that your glycogen stores return to normal levels for your next workout, eat a high carbohydrate meal immediately post exercise, and continue to eat carbohydrates as a part of your normal meals.
Exercise nutrition is a very complex topic, but having a basic understanding of what your body needs in order to perform is an essential tool if you are serious about improving on the bike, or in any athletic endeavor.
Sam Bassetti has been racing at the Junior, U23, Elite and Professional levels in the United States and Internationally since 2009. Relying on his experience and his degree in Exercise Biology, he currently coaches and trains cyclists for Data Driven Athlete and the Team Swift Junior Development Program out of Santa Rosa, Calif. Visit datadrivenathlete.com to learn more. He’s also a frequent contributor to the TrainingPeaks blog.
You must be logged in to post a comment.