Thread:Difference between Tonic, Phasic and Postural muscles (1)

Hello! I'd like to talk about differences between type of muscles in human body.

As I see it (and as I was teached) postural muscles are not always equal to tonic muscles, and even there are some phasic muscles that ARE postural!!

To clarify:

Postural - it means that muscle is used for keeping straight posture of human body

Tonic - means that muscle contains mostly slow-contraction, long-duralibity fibers. These mucles have tendency to over-tension and to shorten (for example in spasticity).

Phasic - means that muscle contains mostly quick-contraction, hi-power, short-duralibity fibers. These muscles have tendency to under-tension (getting weak), and loose. They also lose their mass very quickly while hypokinesia.

For example: gluteus maximus, and rectus abdominis are both postural muscles, but they content mostly phasic fibers. So they are PHASIC and POSTURAL at the same time.

According to this, it's impractical to distinguish Postural and Phasic muscles, becouse term "postural" doesn't refer to conception of different fibers content in muscle, it only means that exemplary muscle is used to keep human posture straight.

Following the line of thought, the only distinction is between TONIC and PHASIC muscles as I wrote above. Term "postural" is seperate term that dosen't refer to features of this comparsion.

I would like to know authors (of this article) opinion about what I wrote above.