% of Fast Twitch / Slow Twitch Fibers and Performance?

jeff828 · #1 09-16.-2008

Hey Guys

First Question, is there a way to find out the percentage of fast twitch/slow twitch fibers a rider has?

Second question is, knowing the ratio of fast vs slow, if you have primarily fast twitch fibers, does anyone have any research and know what percentage can usually be converted over to slow twitch with the proper training to help with FTP, time trailing., etc and if this is relevant to know?
Or would it vary on what you started with, for example if rider A is a sprinter and has 90% fast twitch, 10% slow, he might only be able to convert 5-10% so he will be limited on how much benefit he can get from those fibers, VERSUS rider B who has 60% fast and 40% slow, he might be able to convert up to 20% with proper training , in return become a better road racer, TTer, and will be able to raise their FTP numbers way more than the sprinter can.

Marty Nothstein is a good example, he is a pure sprinter, has won everything on the track, he switched to road racing, did the training but his performances were fair. So if he told his coach that he wanted to win the world TT championships would it be almost impossible because he would not be able to convert that many type2 fibers over that would be needed to do a sub 50min.
Mcewen/Boonen are another example of sprinters, do you think their ratio is not as wide as marty’s and this is possibly why they do better in road races.

Last question, anyone have any research on the above questions and if so can it be correlated to watts, like if a sprinter converts “x” % of those fast twitch fibers he will only add “x” more watts to his FTP?

I am 40, a sprinter, been racing 10+ years, came from bmx, 160lb, can hit 1200-1400w pretty easy, FTP is stuck around 260w, it has increased about 50w over the past 2 years of doing structured workouts, 2x20s etc, is it a reasonable to think I can get a FTP of 325w or even 300w or am I totally off the wall? I race cat 3, can be active and finish top 15, but that’s not good enough, I race the masters 123, can be active and place top 20, sometimes top 10 but that’s not good enough either, how do I play with these guys that have a FTP of 325-350w and get in the top 5, I am sure I can beat these guys in a heads up sprint but getting to the end of the race with more in reserve has been the issue.

Thanks

Piotr · #2 09-17.-2008

Quote:

Originally Posted by jeff828

Hey Guys

First Question, is there a way to find out the percentage of fast twitch/slow twitch fibers a rider has?

Second question is, knowing the ratio of fast vs slow, if you have primarily fast twitch fibers, does anyone have any research and know what percentage can usually be converted over to slow twitch with the proper training to help with FTP, time trailing., etc and if this is relevant to know?
Or would it vary on what you started with, for example if rider A is a sprinter and has 90% fast twitch, 10% slow, he might only be able to convert 5-10% so he will be limited on how much benefit he can get from those fibers, VERSUS rider B who has 60% fast and 40% slow, he might be able to convert up to 20% with proper training , in return become a better road racer, TTer, and will be able to raise their FTP numbers way more than the sprinter can.

Marty Nothstein is a good example, he is a pure sprinter, has won everything on the track, he switched to road racing, did the training but his performances were fair. So if he told his coach that he wanted to win the world TT championships would it be almost impossible because he would not be able to convert that many type2 fibers over that would be needed to do a sub 50min.
Mcewen/Boonen are another example of sprinters, do you think their ratio is not as wide as marty’s and this is possibly why they do better in road races.

Last question, anyone have any research on the above questions and if so can it be correlated to watts, like if a sprinter converts “x” % of those fast twitch fibers he will only add “x” more watts to his FTP?

I am 40, a sprinter, been racing 10+ years, came from bmx, 160lb, can hit 1200-1400w pretty easy, FTP is stuck around 260w, it has increased about 50w over the past 2 years of doing structured workouts, 2x20s etc, is it a reasonable to think I can get a FTP of 325w or even 300w or am I totally off the wall? I race cat 3, can be active and finish top 15, but that’s not good enough, I race the masters 123, can be active and place top 20, sometimes top 10 but that’s not good enough either, how do I play with these guys that have a FTP of 325-350w and get in the top 5, I am sure I can beat these guys in a heads up sprint but getting to the end of the race with more in reserve has been the issue.

Thanks

Yes, you can check your fiber ratio through muscle biopsy, but like VO2max testing it won't tell you anything you don't already know through experience.

I don't know that it's realistic for a sprinter (assuming you are one and didn't simply pidgeon-hole yourself that way) to try to become a climber (325-350W @ 160lbs = 4.4 - 4.8 W/kg). You can certainly improve your FTP, but if you've been at it for a few years and have already plateaued somewhat, a goal of 275-280 W may be more realistic. If you're a sprinter and can't get into top 5 in cat. 3 races, I suggest you get on a team that will help you get to the line in a better position.

Your fiber conversion questions are a bit over my head. I know that some conversion of Type IIB to Type IIA does happen after years of training, but you may need to do some dilligent research to find out how much. Just be careful what you wish for, because you may lose your sprint in the process. Just ask Hincapie, Zabel, even McEwen more recently. And yes, it will happen to Cavendish too. They will never be climbers while no longer being great sprinters. IOW, ride what you brung and make the best of it.

john979 · #3 09-17.-2008

Actually, Type IIB to Type IIA conversion happens fairly quickly. Of equal importance is Type IIA fiber becoming more oxidative, acting as a hybrid between Type IIA and Type I fiber.

Type IIA to Type I conversion is the big unknown, with evidence pointing both ways. This process, if it does actually occur, will take years and may not be of a significant magnitude to turn a Kilo Sprinter into a Tour de France Champion.

I would still get the biopsy, just to have curiousity satisfied. Keep in mind too that a predomenance of Type I fiber alone is not sufficient to allow for increased efficiency; there are other factors as well.

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