Over the weekend I had a couple people who read about “GU” in my blog ask me what it is. Basically it is simple carbohydrates in a goo-like format that are delivered to muscles within minutes of ingesting the material. GU is my favorite fueling method while running a marathon because it is easy to digest, fast to supply the body with energy, and comes in a wide variety flavors. Some of my favorite GU flavors include strawberry banana, mandarin orange, lemon lime, chocolate, vanilla bean, expresso, peanut butter, and peppermint stick.
There is a ton of science behind running nutrition and ratios of carbs, protein, and fats to eat, however carbs remain runners’ favorites for a couple of reasons. First of all, runners burn a mixture of mostly carbohydrates and only some fats while running. Participating in endurance events usually requires runners to take in additional carbohydrates as they run to prevent the dreaded depletion of glycogen stored in muscles. Glycogen is stored in muscles and when converted to glucose provides energy to muscle cells. When glycogen runs out so does a runner’s ability to maintain paces and mental focus (i.e. energy!).
Secondly, the quicker your pace when running the more carbs you burn because carbs are a more efficient energy source for the human body. Eventually if glycogen is depleted the body will try to run itself off of fat, which is not its preferred source of energy. This results in what runners and cyclists call “hitting the wall” or “bonking”. This can lead to extreme muscle fatigue and horror stories of people collapsing while running, being carried off the course, or having their uterus fall out.
Just kidding on the last one although women were not allowed to run marathons until the 1970’s for this last reason. The first women’s Olympic marathon event wasn’t even allowed until 1984 (men started running this event in 1896)!
Hope the little lesson helps!