Run-Down Forums

[Guest]

Is there a way to tell if u have fast fiber
muscle?does weight lifting make fast fiber
mucles to slow fiber.

[Dan]

Fast/slow twitch muscle fiber composition is not an either/or. Everyone has a mix of the two types in varying amounts, and the different fiber types can behave differently in different individuals. Lots of grey area there. It is believe that fast twitch fibers can be developed, but I'm not aware of any unanymous agreement on the matter.

Dan

[Guest]

the only way they can find out is if they cut open your tissue and do like a biopsy or something like that
genetics are a good indicator though

[Anonymously Posted by: 'knowing']

[training2run]

When you go out to run with your friends, do you beat the heck out of them? Yes, then the odds are you have plenty of fast twitch fiber.

On the other hand, do you seldom get tired, but usually come in last or near last in a foot race? Yes, then it's slow twitch that you have.

In my case, I probably don't have a single fast twitch muscle in my entire body, and I can't jump very high either (but I can sure climb). Mad Dog Mike www.training2run.com

[Paul]

One of the best predictors of your personal fast twitch/slow twitch composition is the simple standing vertical jump. If you are a young kid, 1st couple of years in high school, and your vertical jump is over 24", you can assume you have a good amount of fast twitch fibers. If you are in your 20's and your vertical jump is 20" or less, you know you have a lot of slow twitch fibers.
That said, the terminology of fast and slow twitch is a bit of a misnomer. In reality what you are dealing with are high intensity and low intensity fibers. It is important to know this distinction and to know how the fiber types respond to stimuli when you are dealing with training issues. Fast twitch fibers hypertrophy much greater than slow twitch fibers do. So if you are doing a lot of short duration, intense work, and you have a decent supply of fast twitch fibers, that muscle group will get significantly larger.
So the key is not necessarily speed of movement, but the intensity of the movement. If you have no load except for gravity and you are sprinting, the amount of fast twitch fibers determine your speed and acceleration. If you are under a heavy load as in lifting, even though the movement may seem slow, the force requirement is intense so you are still actively recruiting fast twitch fibers.
Fast twitch fibers overwhelm slow twitch fibers in intense movements. Many times the only time slow twitch fibers come into play in sprinting or intense weightlifting movements like the snatch, and clean and jerk in the Olympic movements are at the beginning when inertia is first being overcome. Fast twitch fibers have such a forceful contraction rate, that as the speed or intensity of a movement increase, the slow twitch fibers are left way behind, and add nothing to the effort even if they are firing.
A trickier subject would be the more multi-faceted inbetween fibers. These are fast twitch fibers with an oxidative component. They can be stimulated with both high intensity and low intensity work. They are also the fibers that will change the most with training. If most of your training is endurance oriented, then the fast oxidative fiber (FO) will take on more of an oxidative state. If your training is more of the intense, short duration kind, then those FO fibers will take on more of a glycolitic state.
Getting back to your weightlifting example, if you are doing fairly light weights for 10 repetitions or more you are training more of the slow twitch component. If your training is higher intensity, 5 reps or less, even if it is slow because of the load, you are training much more of the fast twitch component.
It is far easier to train the oxidative component of a fast twitch fiber. It is very difficult, some would say impossible, to change the speed component of a slow twitch fiber.

Paul

[training2run]

The standing vertical jump sounds like a fun and possibly useful test - for those who haven't actually been running since childhood.

From a purely practical stand point (especially for those who are not enamored with jargon, and don't believe that naming something means you control it or necessarilyunderstand it), running itself is a fine indicator.

If you can naturally run fast, you can train yourself to run even faster. If you are a naturally slow runner (or slogger), take up distance running, and leave the shorter stuff and sprints for the "speed demons."

Actually the fast folks might do just fine at distance, but not vicy-vercy - slow is slow. Mad Dog Mike www.training2run.com

[Distance_Guru]

Well put Paul. Another thing to remeber about muscle fiber types is that not everyones slow twitch is all that slow and not everyones fast twitich is all that fast. Geb is a great example of this. With his amazing endurance he has to have a pretty high percentage of slow twitch muscle fibers (at least 50%), he also probably has a pretty good percentage of fast twitch type 1 fibers (FT fibers with oxidative abilities). However his slow twitch fibers undoubtedly contracts at a faster rate than many peoples fast twitch muscle fibers.
_________________
Time is the fire in which we burn

[Paul]

Thanks, DG. I wonder if runners like Geb have a high complement of FO fibers that get trained hard from both sides with their long (1000m-2000m) intervals run at near lactate rate. There has been some evidence of people being able to change some amount of slow twitch fibers into FO and back again. If that were Geb's case, then that would be ideal, since he could train for a marathon and then make the change for the 10K. I'd like to see Geb push the 1/2 mar under 58 min and the 10 mile under 44 if they aren't there already. I'm not up to speed on some of the odder marks. The one hour run would be an interesting one, also.

Hey, this is my 100th post!! Mike made it on Friday. You know what this means?? It means we can train on the track between 2:30 and 6:00!!

Paul

[training2run]

Joe and I tried the standing vertical jump test - you could barely see daylight between our flats and the pavement.

Today was our long-run day. After two hours (2 1/2 for me) we came off the trail, ran to the track, and Joe did a time trial.

Since I had started an hour earlier than he, I could stand around and stretch and do the timing. He's becoming a real animal - doing a time trail *after* a long run.

He's gotten his one mile time down from 12 minutes to 9:35, and can hold 9:42 for three miles...he's doing great. It won't be long until he's down to 8 something. Mad Dog Mike www.training2run.com

[Dan]

I believe Tergat's half marathon record is at 59:18. I think he ran sub-59 (by a second or two) in the race that was later disallowed because it was short by a few meters.

Dan

[training2run]

Can you imagine working that hard, and then being shut down because of a measuring error. I'd want to chew the pavement. Mad Dog Mike www.training2run.com

[Dan]

That would definitely suck. I bet the meet director did a lot of apologizing!!

Dan

[training2run]

hanging by his thumbs, I hope. Mad Dog Mike www.training2run.com[url][/url]