T Nation

Determining Muscle Fiber Make-up

Jeez - all I seem to do these days is ask the questions I should have asked years ago. Anyway - is there a simple way to determine muscle fiber make-up, and what are the implications of this regarding the best way to train?

To be honest I already think I am probably fast twitch dominant, but I’d like to confirm this. Assuming one has a high ratio of fast twitch fibrers, would this suggest that better progress in terms of strength and growth would be made with a low rep range?

First, there isn’t one foolproof five minute test.

Also, keep in mind that like with bodyfat, your body isn’t the same across every muscle group.

Standard tests include the 80% max test, for example, bench 80KGs if your max is 100 kilos and count how many reps you manage to do. 10 reps means standard ratio, 5 reps or below means fast twitch, 15 reps+ means you’re probably more a slow twitcher. A more extreme result (like 2 reps or 20 reps) is more meaningful, of course.
Good old sprints also tell a lot about lower body explosiveness. As do two legged jumps, albeit more about hip explosiveness.

Oh my god man, have you even BEEN to a gym yet?

Just go strength train in a moderate range and over the course of several months you will be able to judge what changes you need to make for different bodyparts.

It’s not really even that important. Your body will adapt to the demands you make of it.

There is no way to determine the ratio other than taking a small sample of actual muscle tissue.

Experimenting is really the only way to go about it. Keep in mind that every muscle is going to have a different ratio, so while your hamstrings may be mostly slow twitch, your chest may be more fast twitch. Just try different rep ranges, keep track of what kind of progress you make, keep whats useful, reject whats useless.

[quote]CappedAndPlanIt wrote:
Experimenting is really the only way to go about it. Keep in mind that every muscle is going to have a different ratio, so while your hamstrings may be mostly slow twitch, your chest may be more fast twitch. Just try different rep ranges, keep track of what kind of progress you make, keep whats useful, reject whats useless.[/quote]

Or better yet, do like most other guys have done who have made progress and stick to the same general rep range long enough to see SIGNIFICANT progress. I am not talking about, “look, I gained 5 whole pounds in 6 months”. If months have gone by and you have made no progress, check your diet first. The rep range is the least important factor assuming you aren’t taking some extreme approach and only doing one rep or 30.

Capped is right about experimentation. No one can avoid learning FOR THEMSELVES what works best. If you even try to, you won’t be making much progress.

This is a game of trial and error. No one is going to hand you some magic approach that always works.

Even if you knew the precise muscle fiber make-up of every muscle in your body, would you really let that dictate the way you train? Say, if your chest was slow twitch and your quads were fast twitch, would you bench only in the 10-20 rep range, and squat only in the 1-3 rep range?

No, you would still progress more if you used a variety of both high and low reps in your training. So don’t worry about the minutia.

Well, X and popular beat me to it.

Good game.

According to Charles Poliquin, the two muscle groups that are predominantly fast-twitch compared the the rest of the body are your hamstrings and triceps.

[quote]Fulmen wrote:
Well, X and popular beat me to it.

Good game.

[/quote]

It seems like this website is beginning to take a turn for the better again.

Finally.

[quote]MytchBucanan wrote:
According to Charles Poliquin, the two muscle groups that are predominantly fast-twitch compared the the rest of the body are your hamstrings and triceps.[/quote]

Polquin always say that about the hammies and I’m sure he has empirical data to back it up. My own experience, however, does not jive with that.

For myself, my hams seem more ST and have always responded better to higher reps. The DoggCrapp gang seems to treat them like that too. A good point was made above that you still need to do low-rep stuff too to keep from getting static.

I guess you’ll need to find out for yourself.

As far as the rest of the body, a good starting assumption is that Push muscles tend towards FT and Pull muscles tend towards ST. Delts seem to be all over the place. Legs should be more ST than upper body.

Again, these are all generalizations and you will have to keep a good workout journal to figure it out on your own.

Good Luck,
Scott

P.S. There’s a general test you can do for kicks, just to see what happens.

You use single-joint/isolation exercises, and you need to know the weight that will cause you to fail at ~10 reps. When I say fail, I mean you couldn’t get another rep w/o extreme cheating.

Do slow and controlled reps. Don’t jerk the weight.

When you fail at 10 (or 9 or 11), immediately remove 30% of the weight and go again. It helps to have a buddy on this.

< 6 = FT**
6-8 = Mixed*

8 = ST**
If your first set is 9 or 11 or whatever, adjust the ranges accordingly.

*Mixed is a relative term, since all muscle groups are mixed fibers.

**Pre-dominantly fast- or slow-twitch. Again, no muscle group is made up of all one or the other.

Don’t do more than 2-3 muscles in a single day.

DISCLAIMER (before I’m severely thumped): This is just a short test and is no replacement for tracking your long-term results.

For example, if your pecs test FT, you may do well to train them with low reps most of the time. Your best success, however, will come when you at least periodically move out of that comfort zone and rep-out on those puppies too.

[quote]evo2008 wrote:
is there a simple way to determine muscle fiber make-up?
[/quote]

Autopsy

[quote]simon-hecubus wrote:

For myself, my hams seem more ST and have always responded better to higher reps. The DoggCrapp gang seems to treat them like that too. A good point was made above that you still need to do low-rep stuff too to keep from getting static.
[/quote]

Most DC guys also do deadlifts every week at 6 reps and lower. The higher rep things are done on stuff like leg curls and (maybe) sumo leg press.

[quote]Petrichor wrote:
There is no way to determine the ratio other than taking a small sample of actual muscle tissue.[/quote]

Every single one of them.