“Yes it does, type IIb and type IIa will convert eventually to type Ia”-martn76
As I said, martn76 can show that fast to slow conversion is possible. So wth is going on, can someone please explain.
What Davan means is that total conversion is not possible.
Type IIa and Type IIb are BOTH fast-twitch. But IIb is faster and more powerful. (If I’m wrong, someone please tell me)
IIa is more in-between. These are mainly affected by environmental factors. You can change these to either type I or type IIb through training.
Changing IIb ---->IIa
or
Type I -------> IIa
is also possible because, through training, you can force fiber types to take on different qualities (white muscle fiber gets a bit redder or a red muscle fiber gets a few streaks of white).
However you cannot change type I straight into type IIb.
training can and does influence fiber type but the reason many studies have found a conversion from type 2b fiber to type 2a is because of how they lift. the same conversion was not found in olympic weightlifters just bodybuilders. so its not lifting weights thats the problem its how you lift weights. they convert because type 2a fibers are more metabolically effecient for the given task. train under circumstances inwhich only the most intense muscle contractions are produced and the conversion will happen towards the type 2b end of the spectrum.
Humans do not have type IIb fibers, mice do. Humans have Type IIa, IIx, and I.
BRO!!! I can’t see the images you’ve posted, none of them even the first one
any way you can upload them again or host them somewhere???
You continue to say this kind of stuff, but the science doesn’t back you up.
From Fry, AC, “Muscle fiber characteristics and performance correlates of male Olympic-style weightlifters,” (2003), muscle biopsy results showed the following:
IIC (OL=0.4 +/- 0.2, Control=2.4 +/- 0.8);
IIB (OL=1.7 +/- 1.4, Control=21.0 +/- 5.3),
IIA (OL=50.5 +/- 3.2, Control=26.9 +/- 3.7)
as well as:
percent MHC IIa (OL=65.3 +/- 2.4, Control=52.1 +/- 4.2)
percent MHC IIB (OL=0.9 +/- 0.9; Control=18.2 +/- 6.1)
There are a relatively large number of studies showing that heavy weight lifting results in a conversion of:
IIx -> IIa.
Olympic lifters appear to have a somewhat GREATER conversion to more oxidative (slower) fibers than powerlifters.
By Comparison, D’Antona, Giuseppe “Skeletal muscle hypertrophy and structure and function of skeletal muscle fibres in male body builders” (2006) shows that experienced bodybuilders (6-12 reps/set. multiple sets, 30 sec-2 min rest) have IIx hybrid fibers that are more numerous and faster than controls, and MHC Isoform distribution that is shifted toward the faster IIx compared to controls (and also compared to Olympic and Power Lifters).