People are born with a pre-determined ratio of fast to slow twitch fibers. These are what determines the energy systems that athletes have a propensity for. Most untrained individuales fall around the 50-50 range, but training in endurance sports obviously increases the ammount and size of the slow twitch fibers. Certain people are born with an ammount of fast twitch fibers alread=y in their body that they cannot change, and will always have a natural tendency towards anaerobic, power type sports. There is nothing they can do about it. Not everyone is ment to be a sub-10 hour triathlete, but not everyone can slam-dunk a basketball either.

tommy

"Certain people are born with an ammount of fast twitch fibers already in their body that they cannot change, and will always have a natural tendency towards anaerobic, power type sports."

It's quite frustrating because my running really sucks. I'm a very fast runner in my AG up to 200 m. After that forget it. Was on the high school track team as a 100 m specialist and anchor for the 4 x 100 relay team. Until I got into tri, the longest distance I ever ran was 400m.

>People are born with a pre-determined ratio of fast to slow
>twitch fibers

Sure, that is true. But it isn't purely genetic because the type of training does matter. There are sub-types within fast twitch fibers. The Type IIb Fast Glycolytic (FG) fibers are the "classic" white fibers, whereas the Type IIa Fast Oxidative Glycolytic (FOG) fibers do have mitochondria and are red colored. Thus, they kind of display some slowtwitch characteristics such as better ability to resist fatigue and perform aerobically instead of anaerobically.

With appropriate aerobic training, the body can gradually convert a portion of its Type IIb fibers to Type IIa. Similarly, with appropriate power training, it can convert Type IIa fibers to Type IIb. So the body has some flexibility in how it responds to training stimulus.

Also, as we age our fast twitch fibers gradually convert to be more slowtwitch-like.

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~~Bob

"Also, as we age our fast twitch fibers gradually convert to be more slowtwitch-like. "

Bob that's good to hear since I'm now middle aged, but my running still sucks. It frustrates me because I can pass people on the bike and then they blow by me on the run. I can easily smoke my fellow AG tri friends on the bike or x-country skate skiing but haven't a chance of getting near them on the run. But then who ever said life is fair.

cerveloguy,

damn, i know how you feel

In highschool i played football, hockey and did javelin, discus and 4*100m relay

I did run a 3000m as well, but i wasnt fast.

This triathlon stuff is sure a big change to my body!!! im definitly not made for this sport yet...about 5'10 and 205ish, but im hoping to get there.

I think it is possible to become good in a sport, but it will not happen overnight. As per the slow muscle/fast muscle fibre stuff, you do have the ability to recruit more muscle fibres through training, it may just take longer to shift from one side of the equilibrium to the other

just my $0.02



-kevin

P.S. check out our webpage and tell me what you think. and sign the guestbook!

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"Anyone can work hard when they want to; Champions do it when they don't."

Good page Kevin. Obviously you run the Kingston Tri. That's one of my favorites.

Hey Kevin,

Our club paid less than 50 per year through the server you probably use for your website. We got rid of the annoying pop-ups!

Matt

www.trikats.com