Sometimes knowledge doesn't prevent you from doing something really stupid, if you choose to ignore what you know but should be well aware of.
Rain And Retching
Last week it constantly rained around here, so I hopped on our stationary bike to do my cardio and went for a 36 minute HIIT regime: warm-up, 4 minutes 200W, 3 minutes 150W etc.
Already after the first 10 minutes I felt that my performance won't be the best, so I went for fewer RPM. But when I finished my unit, my pulse was still above 175 and during the cooldown I started feeling shaky. When I finally got off the bike I trembled and just trying to put on my sweater gave me really bad nausea and led to actual retching. I had to lie down for 15 minutes and take a dextrose tab to get my blood sugar level to normal again.
My Total And Utter Stupidity
While I was lying there on the couch I analyzed what had happened and came to the conclusion that I had been utterly and completely stupid.
I hadn't eaten much that day and felt slightly tired and yet not very hungry. To have energy for my cardio session I had two of those dextrose tabs before getting on the bike. Dextrose is nothing but another word for glucose, the one and only form of carbohydrate the body uses as energy - every carbohydrate you eat and not stored as energy reserve in the form of fat is one way or the other transformed into glucose. A dextrose tab therefore goes directly into the bloodstream and I was swimming in a sudden high of raw energy.
What the body however tries to do is keep a constant supply of glucose going, by always maintaining the same glucose concentration in the blood. If that wasn't the case, we would have more than enough glucose right after we eat, but starve between meals and while we sleep.
Blood Sugar Regulation
So our organism developed a simple, yet elegant way to avoid this and keep the level constant.
When there is too much glucose around, it produces insulin, which gets your liver and muscle cells to store glucose in the form of glycogen. When too little glucose is around, it produces glucagon, which does the exact opposite of insulin and makes your muscles and liver release the stored glycogen and convert it to glucose.
Which works very well when you eat food, whose digestion takes some time. The carbohydrates in it get broken down to glucose and through the bloodstream are distributed to all cells in the body. If the body has all the glucose it needs, the surplus carbohydrates from your food are turned into glycogen and when those reserves are full, too, what still remains is transformed to fat.
Dextrose Without Food?
Now consider what I did: Before I took the dextrose I had low blood sugar because I hadn't eaten and my body was busy producing glucagon - glycogen was turned into glucose to keep me going. But I spiked up my blood sugar with dextrose, which stopped this process, my body released insulin and my liver and muscle cells started to think they have to store glucose. While I was physically exhausting myself.
At the end my blood sugar level had dropped to unknown depths. In essence this is what happens to a diabetic who injects too much insulin and goes into a condition called hypoglycaemia, whose list of symptoms include what I experienced and finish with the happy outlook of " temporary loss of consciousness, confusion, convulsions, coma".
Supplementing dextrose works well when you need some immediate energy around and there are other carbohydrates to buffer it, but isn't a good idea to have in a fasted state and then hop on a bike.
My stupidity amazed me, as I knew all this, but chose to ignore it.
Picture courtesy of US Air Force.