So, is there any place that tells you which muscles contain a lot of type 1 fibers, and which ones contain a lot of type 2a and 2b?
I know the calves are supposed to be predominantly type 1 (80%?), but don’t know any others.
I’m not to sure I will use this as a guide for my exercises (if so, it will be very moderate), but if for anything would like to know for the sake of knowing.
Meatwad
A good rule of thumb that I’ve gathered is that all of your pulling(flexor) muscles are primarily fast twitch and all pushing(extensor) muscles are slow twitch.
But that is only a rule of thumb. If you really want to know, go and get muscle biopisies done on all 200-some or whatever muscles in the body haha.
Typically, the thicker the muscles, the more fast-twitch fibers. But it varies ALOT from person to person. Also, there are studies that show that fast-twitch fibers can actually transform into slow-twitch fibers.
Your activity may cause a shift in the ratio. An example of this would be if you started running marathons; your body would have to start using more oxygen more efficiently, so capillaries would grow thicker around the active muscles, and the muscles themselves would shrink to take on more O2 and less sugar. Fast-twitch muscles can store sugar (glycogen), but slow-twitch muscles cannot efficiently store much oxygen (they can store SOME, and this is why there is dark meat; the muscle actually contains some ferrous iron to store O2)). So, the fast-twitch muscles are larger in part because of their ability to store some glycogen.
It is really still a game of which-came-first, though: are marathoners built the way they are genetically, or as a response to their regimes? Same question goes for the bodybuilder. I think the answer is a little of both; we choose activities that we are able to do with more success because of our body-types, and our bodies continue to develop accordingly.
Anyway- apply this logic to the muscles in your body, think about what kind of work they perform, and you can fairly well guess which ones have more fast-twitch. To know for sure? It would take hundreds of biopsies. Trust me- you will be happier just guessing.
Mike Mahler has written an article which includes a test based on your 1RM to help ‘determine’ your dominant twitch type.
Don’t know the merits, I’ve just read the article.
Google “Train right for your body type.”
Didn’t TC state in a post some time ago, that there has been identified like 17 different fiber types and thereby making the old type 1, 2a&b model obsolete?
I say, be careful using it as a training guideline. The delts, for example, are generally considered to be slow twitch (but not in everyone), but does that mean don’t hit-em heavy? No way.
Anyway, for me, the reps I can do for delts don’t really work on any table. Although I can do 80% of may max 5-6 times, I can only do do 60% about 10 times, max.
The only real cases where I consider fiber type are that
Hams and lats are usually highly fast twitch.
As a result, I think its much better to do many fast sets of 6 or less for these body parts. You can just handle a lot more weight here. I think its true. I can only do 7-8 good pullups, but I can do 2 reps with +90 pounds.
[quote]Owen70 wrote:
A good rule of thumb that I’ve gathered is that all of your pulling(flexor) muscles are primarily fast twitch and all pushing(extensor) muscles are slow twitch.
[/quote]
Does this apply to core muscles? For example what about pecs, traps, lats, obliques, abs, and shoulders?
Meatwad
Yes. They are considered to be a continuum rather than a few specific categories.
DH
[quote]Imbrondir wrote:
Didn’t TC state in a post some time ago, that there has been identified like 17 different fiber types and thereby making the old type 1, 2a&b model obsolete? [/quote]
Triceps are usually more fast twitch and it seems that I’ve read that biceps are too. Something to the tune of 60/40 or 55/45. I believe Dr. Tim Ziegenfuss wrote on it. One must wonder what relevency it has when the ratios are as above. Some even contend that it doesn’t matter at all, that we should always train fast. This deserves some investigation.
DH
I wouldn’t get too caught up in training different muscles according to fiber types. There are many diff fiber types and many hybrid fibers and they exist to varying degrees in different muscles. The soleus may be predominantly type I but the gastrocs have more type II. Different heads of the triceps vary in their fiber type distribution. When you get into compound exercises it gets even more complicated!