What determines efficiency ???

More specifically, through what mechanism/ biological adaptions does efficiency increase in response to training? What contributes to differing efficiencies in different athletes at similar work levels ???

Taken from here:

"It is hypothesized that the improved muscular efficiency probably reflects changes in muscle myosin type stimulated from years of training intensely for 3-6 h on most days."

I hope it helps, but these hypotheses didn't help me any.

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Thanks, and sorry for the brief and abrupt posting, i was at work and trying to not get caught wasting time.

This (posted above) is one of the few references i have found on the subject, the article has been posted on here a few times, but it seems strange that a variable whch directly correlates to power output is only dealt with in passing. Obviously varying muscle composition is a big contributor to differing efficiencies, but i would love to see an in depth treatment of the subject to help get my head around it all.

It is of slight personal importance as my efficiency is too low, I have a Vo2 max of almost 70ml/kg/m but a PVo2max of only 340 watts.

There are lots of things that can potentially affect cycling efficiency. Everything from your muscle fibre type (as hypothesized by Coyle), to cadence, position on the bike, pedaling style, and the condition of your chain and bearings. All of these, except for perhaps muscle fibre type, are potentially optimizable. A nice discussion of most of these can be found in the book Bicycling Science. My product (PowerCranks) has been demonstrated to improve pedaling efficiency in trained cyclists approxiamtely 10% in only 6 weeks. See Luttrell. Another unpublished study by Dixon showed similar benefits.

Why Coyle would hypothesize that Lance's documented efficiency changes were due to his changing muscle fibre type without a single shred of evidence while ignoring all other potential explanations is simply bizarre, and boggles my mind.

I can improve pedaling efficiency by, instead of having your thighs do all the work, spreading the power generation and application workload evenly over the upper and lower leg muscles and hips. This has the same effect on the strain on knees and thighs when using high gears as the difference between climbing a stairs one step at a time compared to two steps at a time. How does your PC equipment improve efficiency and why does it take so long ?

Well, we don't know exactly what they do, although we have several ideas. All those that have studied PC's have shown is we do affect efficiency. Someday, we hope they will also try to ask and answer the question: Why? or what are they doing to effect this change?

What we think they do, and they may do any or all of these things in any one person, depending upon their weaknesses.

1. They distribute the work amongst more muscles, keeping all the muscles working in a more efficient range.

2. They affect the pedaling dynamic, especially the direction of the applied forces, such that these become more efficient.

3. They help the user optimize their pedaling cadence to something that is more efficient for them.

There may be other things but I think these are the three major things we do.

And why does it take so long? Well, in my view, improving efficiency 10% in 6 weeks is amazing fast for such an achievement, not slow. Many think it impossible to change this. Greg LeMond told me it took him years of training to learn how to pedal in the PC fashion and that now people can learn it in months. So, to be able to reliably do so in 6 weeks is pretty amazing. But, what do I know?

Because:

1) Coyle has previously demonstrated a close relationship between fiber type and cycling efficiency;

2) if significant changes in fiber type are possible, they will tend to occur over a prolonged period of time (i.e., the time course makes sense);

3) there really are no other plausible explanations.

In any case, the Discussion of a paper is where the author(s) have the liberty to speculate, and you can't really criticize a paper on such basis if the speculation is plausible (which it was).

Fiber type (and cadence, of course) is really the only thing that has been shown to correlate well with cycling efficiency. Notably, the pattern of force application at the pedals does not, and acute attempts to "improve" said pattern to result in a more "circular" pedaling style has been shown to reduce efficiency.

Oh, phooey. the fact that Coyle has demonstrated a close relationship between fiber type and cycling efficiency doesn't mean that is the only relationship with cycling efficiciency. Further, since the most efficient muscles are the slow twitch muscles, he doesn't explain how a rider like Lance would change his training to increase the proportion of slow twitch muscles to achieve such changes as he documented, let alone document that Lance changed his training in such a fashion. Coyle's explanation is only "plausible" if Lance changed his training in a fashion to encurage such a change. The only way I can envision that someone might make such changes in fiber type would be to do exclusively long slow distance aerobic training. I would suspect high intensity work would be counter productive to this end. I doubt Lance did little high intensity work. Anyhow, there is no documentation that muscle biopsy showed such changes nor that Lance changed his training to encurage such changes so his speculation is hardly plausible.

And, sure there are other possible explanations. Study after study has shown efficiency varies with cadence. Did Coyle control for this? If he did it would seem he would have commented. He did not. further, there have to be other explanations or else the efficiency improvements documented by Luttrell in his study would be impossible, since they occurred over a period of 6 weeks so highly improbable these are due to a change in fiber type so must be due to another explanation (and it wasn't cadence since he controlled for that).

And, sure, I can criticize the paper for his "speculation" as to this being the explanation as to this change (the only significant change seen in Lance over this period of time) without some discussion as to how Lance achieved this change, or discussion of other possible explanations since it was the only really important finding from this analysis. I wonder if Coyle happened to ask Lance how he might explain such a change? Probably not. What would he know about it anyhow? The problem here is Coyle is so highly regarded that shoddy work isn't seen as shoddy so any speculation he puts forth is taken by the masses as having been proven by him. That change was so large and so important to explain Lance's domination (and evidence his domination was not due to drugs) that it certainly need a deeper analysis than a single sentence proclaiming what the author thought was the explanation. His "speculation" in this instance is hardly much more than pure guessing based upon his bias, at least as far as can be determined from the text of the article.

I come from a running background, and find it interesting that we use different terms for the same concept. In running, I think what you're calling efficiency is called economy. Either way, its the same concept - how much useful power output per unit of energy consumption.

To your question, I don't understand what happens at the cellular level to explain an increase in economy. I do know it can be improved by doing hard reps at 98 ~ 100% sprint speed (Daniels, et al)

This is complete amateur speculation, but from a first law perspective, thinking of the body as a closed system, improvements in economy/efficieny could be achieved by minimizing the energy requirements of "auxilliary" systems, e.g. the body's cooling system, and by reducing frictional energy losses in the movements of joints and muscles. That would be a great research area (actually, someone probably already has published some work on that topic).

What's shoddy is that you continue to lean upon misleading "the masses" so that you can sell another set of your PowerCranks.
Even a summary review of your posts here shows that they are continually blown apart by those with scientific minds with no financial gain to cloud their statements.

True for running, maybe, but alas, not true for cycling, which appears to have almost no significantly trainable "skill" element. In cycling, the only differences which have been demonstrated to alter efficiency are metabolic and cellular. Tho' there's apparently money to be made trying to convince cyclists otherwise...

Incorrect, leaving the circular style aside, the correct unweighting technique improves efficiency. In my opinion Coyle did more damage to the advance of cycling (pedalling) science than any other scientist.

Please provide some evidence instead of your opinion. Keep in mind that if you read Dr. Coyle's complete body of work carefully, you will find that early on he was under the belief that a rounder pedaling style was better. One good thging abou him, he isn't trying to sell you something...

actually, it's 'economy' in cycling too..some posters are just using the term to include things that aren't really efficiency.