Fat Burning: Muscle Fiber Type

Dr. Bruce Craig, Ball State University, had a great little article that talked about fat burning and how it happens. It is a little "dry" for the general public, so I have based the next few blogs on his article. I have tried to summarize it with some commentary for you guys. The original article is from the National Strength and Conditioning Association Journal, vol 28, number 5, October 2006 and I can provide a copy if anyone would like it.

Summary: The ability to burn fat during exercise is dependent on exericse intensity and length of workout.

This is a simple, but key point. The main fuel sources of energy during exercise are carbs and fat. You will always be burning a combination of both of these. How HARD and how LONG you exercise will determine if you burn a greater percent of your fuel from carbs or from fat. If you are trying to lose body fat, you want to do exercise that is lower intensity and lasts for a longer time. This type of activity means that more of the calories that are being burned will actually come from fat. Some will still come from carbs, but most will come from fat. When you are doing an exercise or activity that is HIGH intensity, or for less than 3o minutes, a greater percentage of those calories being burned will come from carbs. Why?? Because there are different types of muscle fibers that burn calories differently. These are called Type I and Type II muscle fibers. Everybody has both kinds, but not the same amounts and not equally. Which type does your body have more of? You can probably figure it out by evaluating your workouts and the type of activity that you "naturally" excel at. Make a list of the exercises you know that you have success with in your training. Is it cardio based? Power based? Both? Next week's blog will explain both muscle fiber types and give you a better idea of how your body metabolizes fat and carbs.

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