Distribution of Fibre Types

Training Bodybuilding
1

There was a lot of demand for this info - especially Poliquin types - so here it is. All ratios refer to type I fibers (slow twitch) - to obtain total type II percentage subtract type I % from 100% and voila.

Also, note that these are the averages found by the University that posted them. Furthermore it is theorized type II fibers can convert to type I fibers through type IIC fibers, and vice-versa. Also, type II fibers will convert to type I fibers after 4 months of electrical stimulation an 10 Htz (or was it MHtz).

Muscles with more than 50% of type I fiber are considered tonics and their function revolves around maintaing posture and stability during an activity such as catching a ball or running.

Trunk
Deltoid: 57.1%
Erector Spinae: 56.4 %
Supraspinatus: 59.5%
Frontalis: 64.1%
Trapezius: 53.2%
Latissimus Dorsi: 50.2%
Gluteus Maximus: 52.4%
Infraspinatus: 45.3%
Rectus Abdominis: 46.1%
Temporalis: 46.4%
Rhomboid: 44.6%
SCM: 35.2%
Pectoralis: Unfortunately it wasnt posted and I dont know

Upper Limb
Biceps Brachii: 46.5%
Brachioradialis: 39.8%
Triceps: 32.6%

Lower Limb
Adductor Magnus: 58.2%
Biceps Femoris: 66.9%
Peroneus Longus: 62.6%
Soleus: 87.7% (has highest ratio of type I fibers)
Tibialis Anterior: 73.0%
Vastus Medialis Oblique: 52.1%
Vastus Lateralis: 42.3% (ranging from 39.5% to 51.4%)
Sartorius: 49.6%
Gastrocnemius (lat head): 50.5%
Gastrocnemius (medial head): 43.5%
Rectus Femoris: 35.4%

Something of interest
% of type I fibers in Vastus Lateralis (VL) according to sport:
Cyclist: 61.4%
Canoeist: 61.4%
Runner: 58.9%
Swimmer: 57.7%
WEIGHTLIFTER: 46.1%
Orienteer: 68.8%
SPRINTER: 26.0%
Soccer player: 52.9% (sustained effort with bursts of sharp sprints)
Untrained: 42.1%
***while the University page didnt note, I believe these percentages relate to cross-sectional area of type I fibers due to hypertrophy, and not to number of fibers.

Also of interest, Endurance training increases activity of Oxidative enzymes (which metabolize fats for energy)
Short Bursts of maximal effort on the other hand, increased activity of Glycolitic Enzymes, which means an increase in use of Glycogen for energy.

ALSO of interest, between ages 20-30 yrs old, cross-sectional area of type II fibers is 15-20% bigger than that of type I fibers. By age 70, the cross-sectional areas are roughly equal for either type of fiber.

Sorry for the long post. Just some interesting info I came across.

2

thanks

3

Are these averages of weight-trained or untrained individuals?

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Also, what university commissioned the study and where can an abstract be found?

5

Yessir, a lot of demand.

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Curtin University of Technology: http://physiotherapy.curtin.edu.au/community/educational_resources/ep552_97/fibretypedist.html

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Diesel,
Cool. This is the kind of factual info I expect to get from this site. Thanks for the link.

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Curtin University of Technology

CUnT?

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LOL!!!

10

How about penis fiber distribution? More fast twitch or more slow twitch? :wink:

11

thanx for the info, printing now…

12

Great post

13

ONLY DocT could have caught that.

Diesel: I may have to commend you on this post!

14

sorry.
dont seem right at all.
hamstring is slow twitch?
biceps is more slow then triceps?

contradicts everything Ive heard.

15

Why do weightlifters have such a high slow twitch % in the VL vs sprinters?

doesn’t make sense at all!

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I agree with Spanky. We are missing
something here. No way this could be true. Look at the data!

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intreasting info diesel. But, the question is can we apply this info into the real world scenario, probably not.

Neverthless, intreasting info.

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Thank you very much.

Spanker:

Biceps Brachii: 46.5%

All ratios are for type I fibers (slow twitch). That means the Biceps has 53.5% Fast twitch fibers (type II).

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Coolcolj, for your information, Sprinters are wide known for their MASSIVE legs.

Furthemore it’s widely known to become an elite Sprinter you need to be genetically endowed with above average ratios of Fast twitch fibers.

Fitone, do you have a problem with me? Every damn thread I post I see your name followed by a negative comment. Put it to rest for fuck’s sake.

20

yes right.
rectus abdominus and triceps are more fast twitch then biceps…

COME ON!