What is the limiting factor for aerobic performance in trained athletes? - Page 5

One could argue that muscle fiber type makeup is more important, given that those with a higher percentage Type I and Type IIa have greater FTP than those with a similar VO2 max and more Type IIb fiber.

So how does one find out what type of fibers they have?

Muscle biopsy. One can also infer such to some degree from their Power Profile.

yeah, I thought as much. ouchh! I think I prefer to infer rather than know for sure

Take a look at Horowitz, J.F., et al. High efficiency of type I muscle fibers improves performance. International Journal of Sports Medicine 15(3):152-7, April 1994.

I have wondered many times as others about O2 delivery to the muscles as many other posters and it males lots of sense especially supraphysiological O2 carryng-capacity as well as Blood doping. HOwver those do not happen under normal situation and then are not considered physiological. Being devils´ advocate, if I were too skini and low VO2max but could replicate huge muscle power in my legs I could be the man....regardless of my VO2max,

On the other hand McArdle´s diseases is a disease where the muscle lacks of muscle posphorilase which inhinbits glycogen breakdaown and therefore glycolytic pathway. Therefore highly liming exercise performance, regardless that ventilatory thresholds are found similar in normal subjects or McArdle´s. That is another Non-Physiological condition, but also as in the opposite exapmle of O2 delifery, muscle metabolism es very important and to, me probably the limiting factor.

IN the 70, 80, and low 90´s Cardiorespiratory physiological adaptations came down to lung capacity, cardiac output, capilarisation, VO2max...However moder physiology has turned into Exercise biochemistry and muscle metaolism, since what we are looking at now is at the cell and all the events occuring there, many of which are still unknown and the direction is that it seems that the limiting factor could be in that pathway. About CArdiorespiratory physiology and adaptations we know many things but not many about events at the cellular level.

I believe there is not a single cause. Many of the causes we are talking about are a "requisite" to be elite, but Science still has not rpovided the answer, although modern studies are following the muscular metabolism pathway.

Cheers.

While I totally agree that there are various factors which contribute to aerobic performance (Dr. Coyle has published several outstanding papers on the subject that are freely available), VO2 Max is the ultimate limiter to aerobic performance. However, for individuals of equal VO2 Max, threshold power can vary significantly based upon 1) muscle fiber type and 2) training. Those who posses both a high VO2 Max and high percentage Type I fiber are at a significant advantage...

interesting stuff. Since we're talking about performance ... ultimately watts to the rear wheel ... what about devices like PowerCranks? In laymans terms I view them as 'focused training on the smaller muscles' of the pedal cycle. And the reported/claimed power increases (and Vo2max and perhaps efficiency?) are quite high.

Just wondering ....

__________________
rmur

This from a guy who doesn't like Friel?

Ooops.--Sorry about the mistakes...It is late at night here and I did not double checked my English...so I edited again. Sorry

I have wondered many times as others about O2 delivery to the muscles as many other posters and it males lots of sense especially supraphysiological O2 carryng-capacity as well as Blood doping. HOwver those do not happen under normal situation and then are not considered physiological. Being devils´ advocate, if I were too skini and low VO2max but could replicate huge muscle power in my legs I could be the man....regardless of my VO2max,

On the other hand McArdle´s diseases is a disease where the muscle lacks of muscle posphorilase which inhinbits glycogen breakdaown and therefore glycolytic pathway. Therefore highly liming exercise performance, regardless that ventilatory thresholds are found similar in normal subjects or McArdle´s. That is another Non-Physiological condition, but also as in the opposite exapmle of O2 delifery, muscle metabolism es very important and to, me probably the limiting factor.

IN the 70, 80, and low 90´s Cardiorespiratory physiological adaptations came down to lung capacity, cardiac output, capilarisation, VO2max...However moder physiology has turned into Exercise biochemistry and muscle metaolism, since what we are looking at now is at the cell and all the events occuring there, many of which are still unknown and the direction is that it seems that the limiting factor could be in that pathway. About CArdiorespiratory physiology and adaptations we know many things but not many about events at the cellular level.

I believe there is not a single cause. Many of the causes we are talking about are a "requisite" to be elite, but Science still has not rpovided the answer, although modern studies are following the muscular metabolism pathway.

Cheers.

I doubt this would occur as the best aerobic performers all have comparatively high VO2 Max as a prerequisite.

[QUOTE=john979][QUOTE=Urkiola2]Being devils´ advocate, if I were too skini and low VO2max but could replicate huge muscle power in my legs I could be the man....regardless of my VO2max,It was just an extreme agument...although you would be very surprised sometimes...at least with elite cyclists.

Do you have any specific examples?

As I mentoned several times before, VO2max is a prerequisite to be an elite athlete but it is actually a "poor" performance indicator for a same (homogeneous) group, especialy elite athletes. Anyone, and there are many labs worldwide, working with elite athletes could confirm you this.

As I mentioned also, many elite athletes obtain their best performance years long after reaching their VO2max...and what I have observed is that the correlation between lactate oxidation ("washout") and drecreased blood lactate accumulation and performance is extremely tight. At least from my experience and results. That is for an individual athlete comparing with him/herself, but a very similar occurs with any elite athlete. For the most part, and again from my data working with very different sports, blood lactate accumulation is the laboratory´s diagnosis which discriminates the best among athletes.

I asked for the person's educated opinion of them. Surely no harm in that?

__________________
rmur