Carbohydrate loading

When most think of carbohydrate loading, the classic method of low carb consumption coupled with bouts high intensity exercise followed by a high intake of carbs a few days before competition comes to mind. The result, according to the theory, is super-compensation of glycogen storage in the muscle cells and liver. The theory holds that one must deplete their glycogen stores prior to consuming or loading carbs in order to facilitate super-compensation.

The average person’s total amount of muscle glycogen is approximately 300 – 500g depending on their gender, size, and level of training. The liver stores between 60 and 120g. A linear relationship exists between the depletion of muscle glycogen and fatigue during exercise. With less glycogen to produce glucose, hypoglycemia begins to affect the athlete. Typically, a person with a blood glucose level below 70 will start to feel light headed, lethargy, and have cold clammy skin. A highly trained athlete, on the other hand, can train at much lower levels than 70 for long periods of time.

As with all training topics there is conflicting evidence on what is the best method to achieve super-compensation of glycogen stores. studies are reporting similar results to the classic method, which so many athletes swear by, without carb depletion, while tapering their training (1,2,3). One thing is for sure, carbohydrate levels play a key role in training and competition success.

In order to figure out what works best for you, try different methods and keep a detailed journal. We all process carbs the same way, but we metabolize them at different rates. Keep mind, studies on training are by no means the end all be all. There are too many variables in most training studies to be reliable. Athletes, especially endurance athletes are over-trained. It is my opinion that athletes who are achieving super-compensation without depletion coupled with bouts of intense training, are doing so because they are over-trained and under-fed before starting the process.

The body is constantly working to stay in homeostasis. Physiology shows us glycogen storage is finite; the body needs a reason to super-compensate. Achieving a glycogen depleted state over a period of time produces an insulin sensitive environment, which is essential for more than normal levels of glycogen storage.

1. Eur J Appl Physiol 2002;87:290-295
2. Am J Physiol Endocrinol Metab 2003;285:E1304-E1311
3. Int J Sports Med 1981;2:114-118

  

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