You have three types of muscle fiber that make up your "muscles," and this is sometimes called muscle composition.

Muscle composition is important because it's the fitness training that targets the super fast-twitch muscle that makes your body produce the most powerful body fat-reducing, muscle-toning, fitness hormone in your body, growth hormone.

 

  Muscle Fiber Types

 

The average person has approximately 60 percent fast muscle fiber and 40 percent slow-twitch fiber (type I). There can be swings in fiber composition, but essentially, we all have three types of muscle fiber that need to be trained, (Muscle, Genes, and Athletic Performance, September 2000, Scientific American, Jesper).

 

The fast-twitch muscle actually has two types of fiber -- fast and super-fast. The fast muscle (what the researchers call IIa) moves 5 times faster than the slow muscle, and the super-fast (called IIx or llb) moves 10 times faster than the slow muscle fiber.

The following chart shows that while there are differences in muscle fiber composition, muscle types can be developed based on the way they are trained.

 

Muscle Fiber Composition

 

 

Sprinters have higher percentages of the super-fast (IIx). Endurance trained individuals have more slow muscle fiber (type I). 

 

While we are born with slightly different muscle composition, the point is; super-fast muscle can be developed if exercised properly. And fast-muscle fiber should be developed because this type of muscle opens a new world of benefits from anaerobic sprinting types of exercise.

 

Why is this important?

 

Researchers show that anaerobic exercise (short, quick-burst, get you winded fast) is the type of fitness training that increases exercise-induced growth hormone.  And growth hormone is, without question, the most powerful body fat-reducing, muscle-toning, anti-aging, and anti-middle-aging agent known in science. 

 

Yet, when we finish high school (perhaps with the exception of a few that compete in college and the small number that make it to the pros), we become slow-twitch exercisers at age 20. And this is a huge mistake!

 

Many continue developing slow-twitch muscle (less than half of their muscle fiber) with weight training, jogging, and cardio at the gym, but drop the training that develops their fast muscle fiber. Actually, if you think about it, we start the muscle atrophy process (the wasting away of muscle) on half of our muscle fiber ... AT AGE 20! 

 

No wonder we have an obesity epidemic and this year, 650,000 Americans will hear their physician say, "You have diabetes." 

 

The cure for the national obesity crisis, the cure for the middle-age somatopause, the cure for insulin resistance and (in many cases) diabetes, and the cure for the high cost of healthcare--is so simple, that we keep missing it. 

 

The cure is natural. It's free. But it can't be done overnight because the muscle fiber needed to perform high-intensity anaerobic exercise has atrophied (wasted away).

There's great news?

You can build back your fast-twitch muscle fiber by performing plyometrics to build the fast muscle (IIa) and performing sprinting types of training to build the super-fast (IIx) to the point where you can release exercise-induced growth hormone. You can do it, but you must start slowly and progressively to build your fast muscle fiber. Warning, if you go too fast, too soon, you'll risk injury. Think in terms of a progressive 6 to 8 week build-up period.

 The Take Home

Consider doing more than developing your slow muscle fiber with weights, cardio, and jogging. Don't neglect slow-muscle because this is 40% of your muscle fiber, and to a degree, it serves as a base for the development of the fast and super-fast muscle fiber. Simply tailor your fitness plan to include exercises that develop your slow, fast, and super-fast muscle fiber.

Have a great day!

Phil Campbell, M.S., M.A., FACHE
Author Ready, Set, GO! Synergy Fitness

 

MORE INFO

National Institutes of Health research cited in newsletter,
Research Summary 1

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