mighty_wombat

Hi guys, first off, i'm not a physiological egghead by any means but i know everyone is made up of slow and fast twitch muscle fibers more or less. For hypertrophy i have read it is better to have more fast twitch muscle fibers.

I read this article awhile ago by Shane Giese:
http://www.teenbodybuilding.com/shane6.htm

Most say 8 to 12 reps is what you should shoot for. And looking at the chart in the article it makes sense, it lists 9-12 reps as excellent for fast twitch muscle fibers (type IIa), and 6 to 8 reps as excellent for fast twitch muscle fibers (type IIb).

My question is what if your mainly slow twitch muscle fibers? It lists 6 to 12 reps as very low to low in working those muscles. 25-50 is listed as excellent for slow twitch muscle fibers (type I). Yet i have not read anywhere that recommends 25-50 reps...

I'm a bit confused here, do we try to work fast twitch muscle fibers that might not be there (wishful training???)? Or does working low reps change slow twitch muscle fibers into the more preferable fast twitch muscle fibers?

Please excuse me if this has been talked about before, but i don't seem to be seeing much results training with low reps for a couple years now, i have a feeling i am mostly slow twitch muscle fibers. Any input would be great, thanks for your time reading this.

topolo

I have type II muscle fibers.....in my pants

LexusGS

How the fuck can you know what type of muscle fibers you have?

TJ Cline

have to go get a muscle biopsy done

Rock_fght

a big strong person (sprinter) has lots of fast twitch fibers and a skinny marathon runner has mostly slow twitch fibers.

Age: 16
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Var

Like Foreman said, without a muscle biopsy you can only guess at your predominant fiber type. Best approach is to use both high reps and low reps to keep your body guessing and find what works best for you. I've found that I'm (guessing here) more fast twitch. Therefore, I usually build my routine around heavy weights/lower reps and use higher reps periodically to fight plateaus.

Finally, most of the reading I've done and anecdotal experience I've had shows that reps higher than 14 or so will only build local muscular endurance in most people, not hypertrophy.

Damn that was long-winded.

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CowPimp

Fast twitch fibers are capable of hypertrophying to a greater degree than slow twitch fibers. So, this should really be the focus of your training if mass and strength are your goals.

Also, you always stimulate your slow twitch fibers to some degree, except there is some evidence suggesting otherwise during certain explosive dynamic effort type movements. Fibers are recruited in order from slowest to fastest as necessary. So, during maximal effort exercises (A one rep maximum), you are recruiting more fibers than with lighter weights.

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Phred

Generally most muscle grps (bi, tri, pec, delts, etc) have both slow and fast twitch fibers. However, the calfs, forearms and to a lesser degree the delts are made up of more slow twitch fibers. And the opposite is true for the other muscle groups. Now it is not like a 25/75 ratio. It is more like a 45/55 ratio. So there is not a lot of difference, but enough that you may want to consider going more reps with the muscles made up of more slow fibers. The question of how many reps greatly depends on the individual. I have read some studies that indicate the fast twitch fibers respond to the rep ranges of 6-12 and some studies that suggest 8-15. And the slow twitch fibers rep range is more in the 12-25 area.

The best way to find out what works best for you is to work out in a specific rep range and monitor your results. Change the rep range and monitor your results. After several months of data, you should see what rep ranges work best for strength and which ones seem to work best for muscle growth. This means keeping track of exercises/reps/wts/etc. And keeping your diet fairly consistent as well. IMO, One of the strengths (no pun intended) of p/rr/s is that you target smaller more specific rep ranges within the normally accepted rep ranges. And therefore have a better opportunity to damage all the fibers.

Bottom line is everyone is different, and what works for me may not work for you. So experiment and monitor your results.

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Lepa

You may have more slow twitch fibres than fast twitch, but it will not be as high a percentage as you seem to think. Slow twitch fibres have the potential to hypertrophy yes, but only to a small extent (approx. 7-22%).

It is stupid to be doing 25-50 reps if you are trying to gain mass, due to the small ability of slow twitch fibres to grow. And without a muscle biopsy, you cannot be sure you have more slow twitch fibres anyway. I wouldnt be making that assumption.

I think that the reason you have not grown much is probably due to your diet, or that you are overtraining.

I wouldnt even be considering doing 25-50 reps if you are looking at growing. Keep to 8-12 reps, make sure u arn't overtraining, and eat!

And muscle fibres can not change between slow and fast twitch, but with endurance training, some type 2b fibres can change to type 2a.

Mike.

mighty_wombat

thanks to the last 4 posters. i will stick with low reps still along with my high reps, but i will try even more reps when i do high reps (but only up to 25 max), and keep track of all the results and my diet better, i think my inconsistant diet and not keeping track of my reps/results may have been hurting my goals.

i did not know it was only a 55 to 45 ratio even with more dominate slow twitch muscle fibers.