Muscle Fiber Question(s)

I found the thread...

http://www.letsrun.com/forum/flat_re...3219327&page=0

I think I would have to agree with the statement -- not many people are physically capable of running a sub-5 minute mile.

You can talk about different proportions of slow twitch (Type I) and fast twitch (Types IIa, IIb, and IIx), but I suppose that's only one limiting factor. For example, some may have the right muscle combination, but lack the mental strength or motivation to train for it and race it.

I'm not an expert on muscle recruitment, but I've seen some arguments here, in some of the few threads not about global warming. There has been some talk of fast twitch muscles becoming oxidative with training, but I've also seen some clarifications that, technically speaking, the muscles aren't "recruited", but nevertheless, the "unused" muscle fibers make adaptations which allow them to release their glycogen, making it available for use by the active muscle fibers. This probably helps in marathons, rather than the mile.

In any case, I don't think we speak of a significant amount of muscle fiber conversion, or its equivalent.

If you equate a 5 minute mile to a 36:46 10K time, and look at any typical 10K roadrace, you see that it is typically less than 10%. Furthermore, consider that the population sample within a 10K race is likely biased, and generally can run faster than a general sample of the population. This leads me to agree with a statement that "a small percentage of people are born [capable] of running a sub 5 minute mile".

rekrunner, thanks that was alittle helpful and greatly insightful. Do you have any recommended reads for me?

I'm calling bull$#!+ on this. As far as males go, I'd say most every male born has the correct mixture of muscle fibers to run a sub-5 mile. This may not be true by high school when a kid has had 13 years of opportunities for something to go wrong with the body, but I seriously doubt it has anything to do with muscle fibers. I'd say 99.99999% of the population never tries to reach their running potential and that 99.999% of runners don't even try to reach their running potential.

The human body isn't very different. My guess is that a majority of males with a decent coach who started running at age 13 (start of high school) would easily break 5:00 in the mile by 21 (end of college). Not doing so has much more to do with factors that aren't muscle fiber related.

Eh, you have Type I (slow oxidative) and Type IIa and Type IIb (Fast oxidative and fast glycolytic respectively) fibers, which are somewhat malleable, especially Type IIb. You can train Type IIb fibers to be essentially Type IIa fibers, and you can somewhat convert Type IIa fibers into Type I fibers, but it's not a complete conversion. Type II fibers have a protein which allows them to contract faster than Type one fibers, and Type I fibers are always going to have more mitochondria than Type II fibers. Some (very few) people don't respond much to any form of training though, so they're pretty much screwed.

As for the 5:00 mile, that's kind of a pointless argument. The only 20-30 year old healthy men out there not capable of training to a 5:00 mile are those who either have an extremely high proportion of Type IIb fibers or guys who are just not built like runners (think tall, muscular and thick boned). Most other males probably could run a 5:00 mile given training.

I can agree that most will never try and reach any kind of running potenial and most will have a coach or coaches that will more hender than help those who do. However my over all question is not really concerned with weather ppl try and fail but rather; I want an answer if we are all pretty much lumped into three general muscle fiber make-up's?

My question stems from the fact that I coach alot of beginngers, it is very easy to get them to improve and it is easy to see as they approach their limits (as far as I can see taking them). I just don't understand that limit minus a few factors...

Thank you this is more of what I was looking for.

dumbass wrote:

My question stems from the fact that I coach alot of beginngers, it is very easy to get them to improve and it is easy to see as they approach their limits (as far as I can see taking them). I just don't understand that limit minus a few factors...

Form drills and more mileage. Any young person running 70+ mpw with decent form should be able to run sub-5.

Gonna go out on a limb here... wrote:

dumbass wrote:

My question stems from the fact that I coach alot of beginngers, it is very easy to get them to improve and it is easy to see as they approach their limits (as far as I can see taking them). I just don't understand that limit minus a few factors...

Form drills and more mileage. Any young person running 70+ mpw with decent form should be able to run sub-5.

Sorry when I said beginngers I meant older ppl new to running or at least new to training. I tend not to have any real problems with my kids. It's the men who are around 36 or 37, and a big part of the problem is they don't want to stick it out in the long run. They start to improve and then leave and just try to repeat what I gave them. I try to explain that this will not work but it is what it is...however the ones that I am referring to for coming close to their limits are my marathoners, I use a mile time trial to measure fitness every two to three months and while they are not training for a mile race I feel that they should be running faster given other workouts. My long term ladies always seem to run dead on for my expectation and they are not limited by my expectation because I never give them a time to aim at.

Gonna go out on a limb here... wrote:

dumbass wrote:

My question stems from the fact that I coach alot of beginngers, it is very easy to get them to improve and it is easy to see as they approach their limits (as far as I can see taking them). I just don't understand that limit minus a few factors...

Form drills and more mileage. Any young person running 70+ mpw with decent form should be able to run sub-5.

Sorry when I said beginngers I meant older ppl new to running or at least new to training. I tend not to have any real problems with my kids. It's the men who are around 36 or 37, and a big part of the problem is they don't want to stick it out in the long run. They start to improve and then leave and just try to repeat what I gave them. I try to explain that this will not work but it is what it is...however the ones that I am referring to for coming close to their limits are my marathoners, I use a mile time trial to measure fitness every two to three months and while they are not training for a mile race I feel that they should be running faster given other workouts. My long term ladies always seem to run dead on for my expectation and they are not limited by my expectation because I never give them a time to aim at.

Gonna go out on a limb here... wrote:

dumbass wrote:

My question stems from the fact that I coach alot of beginngers, it is very easy to get them to improve and it is easy to see as they approach their limits (as far as I can see taking them). I just don't understand that limit minus a few factors...

Form drills and more mileage. Any young person running 70+ mpw with decent form should be able to run sub-5.

Sorry when I said beginngers I meant older ppl new to running or at least new to training. I tend not to have any real problems with my kids. It's the men who are around 36 or 37, and a big part of the problem is they don't want to stick it out in the long run. They start to improve and then leave and just try to repeat what I gave them. I try to explain that this will not work but it is what it is...however the ones that I am referring to for coming close to their limits are my marathoners, I use a mile time trial to measure fitness every two to three months and while they are not training for a mile race I feel that they should be running faster given other workouts. My long term ladies always seem to run dead on for my expectation and they are not limited by my expectation because I never give them a time to aim at. Rather I just tell them they are in mile PR shape so get in a hard one so we can ajust their training paces.

This pretty much nails it on the head. With the whole "conversion" thing, you don't really convert, so to speak. What you do is change the reaction times of the fibers. You can make them slower or faster, depending on training. In the case of type IIa fibers, you can train them so they have more mitochondria, but they still pale in comparison to the amount that type I fibers will have.

Also, humans have type I, IIa and IIx. IIb is only in animals. When the scientists were first examining the muscle tissues, they were using animals(dogs I believe) as they were easier to obtain. When they started looking at cadavers, they saw that humans had a different type II fiber than IIb, hence IIx. Very few humans, such as elite sprinters may have IIb fibers, as those are extremely fast reaction time.

Semantics but humans don´t have FTb fibers, those are FTx fibers.

Your welcome. Recommended reads? You mean besides the "letsrun forum"? Well that seems like a broad question.I don't have any recommended reads regarding muscle types -- I'm not really a muscle expert (although I have lifted weights in the past) nor did I ever do much research.I could direct you to wikipedia:http://en.wikipedia.org/wiki/Musclesor here's another site which basically exceeds all I want to know about how to train the different muscle types:http://www.endurancefactor.com/Articles/article-heartintro.htmlRegarding your training, and your athletes hitting their limits, I have read a small handful of training books:- Daniel's Running Formula- Some Lydiard Books, by Lydiard, by Ron Daws, and the latest one by Keith Livingston, "Healthy Intelligent Training"- The Lydiard website http://www.lydiardfoundation.org/- Timothy Noakes "Lore of Running"- Matt Fitzgerald's "Brain Training"I have a couple more books on my wish list:- Matt Fitzgeralds' "Racing Weight"- Ross Tucker, Jonathan Dugas, and Matt Fitzgerald "The Runner's Body"And finally, I did get a copy of "Once a Runner" (the new printing), and read it, and rather enjoyed it.

dumbass wrote:

rekrunner, thanks that was alittle helpful and greatly insightful. Do you have any recommended reads for me?

I agree that there may be other more important reasons besides muscle fiber type distributions, and that muscle fiber conversion likely doesn't play a big role -- I think I tried to say that.Nevertheless I'd say more people are physically incapable of running sub-5:00 for the mile, than are capable. I still say much more, for all the physical and mental reasons. For example, not many sprinters could do it. Maybe my method is flawed, but seems to me to provide the right perspective and magnitude. I'm happy to be proven wrong though. Good luck trying to show that only 1 person in 10,000,000, and only 1 runner in 100,000 even tries to reach their running potential. Those figures seem just a bit too low.

Pamcake wrote:

I'm calling bull$#!+ on this. As far as males go, I'd say most every male born has the correct mixture of muscle fibers to run a sub-5 mile. This may not be true by high school when a kid has had 13 years of opportunities for something to go wrong with the body, but I seriously doubt it has anything to do with muscle fibers. I'd say 99.99999% of the population never tries to reach their running potential and that 99.999% of runners don't even try to reach their running potential.

The human body isn't very different. My guess is that a majority of males with a decent coach who started running at age 13 (start of high school) would easily break 5:00 in the mile by 21 (end of college). Not doing so has much more to do with factors that aren't muscle fiber related.