Hello fitness enthusiasts! It’s time for another exciting and educational edition of the Joe’s Corner Blog. This week I will be discussing the various muscle fiber types that can be trained and what they do. For the purpose of this blog, we will assume that there are four types of muscle (it is debated that there are only three in the scientific world). This is another one of those subjects that can make a person’s head spin around, so, I will try to keep the scientific talk to a minimum and be as basic as possible. The training styles are also basic examples and should be discussed more in-depth with a trainer with your training goals in mind.
Some science stats for you! Picture via http://www.barbellmedicine.com/potpourri/dynamic-fitness-coach-preview-muscle-a-p/
Simply said, the four types of muscle are Type I, Type IIa, Type IIx (aka Type IIc or Type III), and Type IIb. Each of these muscle types has differing properties for the speed in which it moves, its resistance to fatigue, the action it performs, its maximum time that it can be used, its power output, its capillary supply, its oxygen capacity, and its main fuel storage type. The Type I muscle is much slower than all of the Type II (III) muscles.
Type I muscle fibers are fairly slow moving and utilized during endurance and aerobic exercises due to their high resistance to fatigue. They are mostly utilized during walking or the basic body functions in life such as posture. They do not provide a lot of force and are primarily found in individuals who are sedentary. While they can be used for fast explosive movements, their storage of fuel for this activity is extremely low and will only last a few seconds during fight or flight situations (leaping out of the way of cars bearing down on you as you’re trying to cross the street, I’m looking at you crosswalk!). In a weightlifting session these muscles would be trained with a low weight, high repetition sets of (just a random example) 21-15-9 or 15-12-10 reps with at least a one minute rest between sets.
Type II muscle fibers are much faster than Type I, but can be further divided into three classes [Type IIa, Type IIx(III Hybrid), Type IIb] with varying speeds. Type IIa is moderately faster than Type I, but much slower than Type IIx (III) and Type IIb. Type IIx is faster than Type IIa, but slower than Type IIb (basically, Type IIb is The Flash and Type IIx is only Superman).
I swear these posts keep getting more and more nerdy. http://www.comicvine.com/thor/4005-2268/forums/thor-and-superman-strenght-equality-749966/
Type IIa training is like that of a Bodybuilder or Powerlifter. These two styles incorporate heavier weight and a lower rep set. For example, a Bodybuilder would do a hypertrophy sets of 12-10-8 or 10-8-8-6 reps where as a Powerlifter would do a power sets of (remember these are just primary examples) 6-6-6-6 or 6-4-4-2 reps with a one to two minute rest period between sets (this helps to allow your fuel source to resupply). In the world of running, this muscle fiber type would be trained during 400m runs (not quite a sprint, but also not a jog).
Type IIb training is like that of an Olympic Weightlifter, dynamic and explosive movements. This muscle type has the highest fatigue rate due to the explosive movements and weight involved. The sets are similar to that of the Bodybuilder and Powerlifter, but the body mechanics and movements are more complex and involved, muscularly speaking. For these reasons, the rest period between sets is anywhere from 2-7 minutes. In the world of running, this muscle fiber type is best trained via sprints.
Type IIx or Type III is a hybrid muscle type that has characteristics somewhere between Type IIa and Type IIb. It is for these reasons that it is a widely debated subject that it is a Type II fiber or a completely different animal and Type III. Is your head spinning yet? Mine kind of feels like it’s in a Harlem Globetrotters game.
That’s all I have for this week’s edition! If you have any comments please leave them down below or feel free to email me at Joe@dedicatedfit.com. Don't forget to check out the online workout database and to check out the other blog posts from this week by Logan, Dakota, Sage, and Kylee. Until next week, stay healthy everyone! Yuhp! Still spinning!