Weight Training Routine Based on Muscle Fiber Type

September 29th, 2007 by Paul Johnson

The skeletal muscle tissue is composed of two main types of muscle fibers. There is some subtypes, but the main ones are Type 1 (slow twitch) and type 2 (fast twitch). Both are very different metabolically, structurally, and how they function. The amount of fibers of each type, varies widely in each person and even between each muscle part. Type 2 are the large muscle fibers that are known for power and for contributing to most muscle growth.

Muscle fiber makeup is one reason why people have "lagging" muscle bodypart and why some struggle to put on muscle compared to others. Each fiber responds best to different types of training. The type 2 slow fibers respond best to low reps, very heavy weight, with long rests. Type 1 does better with light weight, many repetitions, and little rest. When lifting a weight, you are going to use both types to some degree. For example, heavy weights will recruit most of the slow type 1 fibers, but few of the faster type 2 fibers.

Unfortunately, our fiber type for the most part, cannot be changed to a significant degree through training. We can get some of the other subtypes to "act more" like type 1 fibers through training, but it's limited. It makes sense that if each muscle fiber is in different distrubution between each bodypart, we should use specialized training for each muscle.

One reason why you almost never hear bodybuilders discuss training each muscle part differently, is because it is very complicated to gear training around each muscle. You will first have to find out which type each muscle part is composed of(through training) and then use different training for each part. It can get complicated and most bodybuilders figure it will all "even out" in the end, if they just train all the muscles the same way. Most bodybuilders have done some muscle fiber type specific training, like with squats and shrugs at higher reps. It is taught among bodybuilders because they are told these muscles respond better to high reps.

The most sensible and methodical training routine for gearing around muscle fiber type, is one I found by Frederick Hatfield. Ph.d. He is also known as "Dr. Squat" and a well known author in excercise physiology, including the well known "20 rep squat". You can find his detailed technical writeup on muscle fiber type training here.

  1. Greg R on March 9th, 2009

    This article INCORRECTLY identifies Type 1 as fast twitch fibers and Type 2 as slow twitch. The exact opposite is true.

  2. admin on March 31st, 2009

    Your right. I fixed it. Thanks for pointing it out, I sometimes get the two backwards. It’s just a minor change, the article is still ok.

  3. Muscle Builder on April 19th, 2009

    lot of usefull info 😉 thank you 😉

  4. Fred on January 5th, 2011

    @admin: I think you forgot to make the correction in paragraph 2. Still a good article, I just wish there were more actionable conclusions.