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).
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!