I was doing some casual research online about energy metabolism, as I’m experimenting right now with my diet, etc. I read in a Wikipedia article about glycogen this description of glycogen debt:
Due to the body’s inability to hold more than around 2,000 kcal of glycogen,long-distance athletes such as marathon runners, cross-country skiers, and cyclists go into glycogen debt, where almost all of the athlete’s glycogen stores are depleted after long periods of exertion without enough energy consumption. This phenomenon is referred to as “hitting the wall” or “bonking”. In marathon runners it normally happens around the 20 mile (32 km) point of a marathon, where around 100 kcal are spent per mile, depending on the size of the runner and the race course. However, it can be delayed by a carbohydrate loading before the task.
When experiencing glycogen debt, athletes often experience extreme fatigue to the point that it is difficult to move.
Does that sound familiar? “Extreme fatigue to the point that it is difficult to move?” Marathon runners who deplete their muscles’ stores of glycogen get to enjoy a little taste of the ‘ol McArdle’s Disease. Because the muscle cells encounter that “energy bottleneck”, i.e., there is no more glucose to create ATP to drive muscle motion, their muscles simply stop responding.
What’s the Significance?
This is noteworthy because an another affirmation that, no matter how healthy, fit and capable of normal exercise people may think you are, if you have McArdle’s Disease there are in fact limitations on what you are capable of, limitations that are beyond your control. It is important for people with McArdle’s to remember this, because years of coping with undiagnosed symptoms often lead people to simply believe they’re out of shape.