Sciguy wrote: "Sorry but it's you who really don't understand and are unwilling to admit your error. Please feel free to contact them if you'd like a little remedial schooling.
From Denis Loiselle- bold added by me
- Denis Loiselle <
ds.loiselle@auckland.ac.nz> wrote: > Dear Hugh > > I infer that you are familiar with our 2005 Review, in general, and its Figure 1, in particular. There is much to be learned from the Figure but, germane to your enquire is the constancy of slope across a wide range of work-loads and individuals ranging in 'cardiovascular fitness' from sedentary folk to endurance athletes. 'Constant slope' implies constant 'cycling efficiency'. That is, a trained athlete can perform work at a higher rate but is subject to the same basic energy-converting limitations - both mechanical and metabolic. In all cases, the efficiency is approximately 20%. > > I have no doubt that your new training technique can produce an increase of power. But I would predict that your result has not changed your cyclists' efficiencies - as the Figure implies. > > Exercise Physiologists selectively turn to either the treadmill or the stationary bicycle ergometer for estimates of efficiency. The reason for this is that walking, running and stationary cycling are LOW SKILL activities. > > Finally, I am moved to state that Appeals to Authority, such as "I'm a doctor, so believe me", have no place in Science. Recall Einstein's response when, upon arriving at work one morning, his secretary informed him that a book had just been published entitled, "One-Hundred Scientists Against Einstein". His reply, 'One would suffice'. > > Yours sincerely, > Denis Loiselle "
and then the reply from: Chris Barclay:
Hi Hugh Let me add to Denis's comments. I think your doctor colleague's argument is founded on the false statement in the first sentence that you quote: there is, in fact, no evidence that human muscle efficiency is 40%! As Denis pointed out and as you seem to know, our best estimates of overall efficiency (i.e. using oxygen cost as an index of energy input) of human muscle are those measured during cycling. In that mode of activity, there can be no power generated by elastic recoil of tendons that had been stretched by the effects of gravity, as there is in running for example. Obviously there is additional energy expenditure by muscles not directly associated with power generation and, as you suggest, there maybe a small component of energy expenditure to overcome resistances of the cycle itself. I think the idea of calculating delta efficiency is to minimise the contributions of these factors to estimates of efficiency. So cycling data suggest that muscle efficiency, excluding resting metabolism, is about 25%. Where might the figure of 40% come from? It most likely is a value taken from frog muscle, the classical muscle preparation. And furthermore, that figure only applies to the conversion of energy from ATP into work thus does not include the energy lost in converting metabolic substrates into ATP. And even that is not strictly correct as the 40% figure used the enthalpy change associated with ATP breakdown as an index of the energy input to the system and this is not the energy from which work can be extracted! A serious issue to understanding efficiency is thus revealed: the energy input term, the denominator of the efficiency formula, can be defined in multiple ways and thus affects the value of efficiency calculated. The 2005 review went to some lengths to clarify the different definitions and to quantify how they are related (and the data in the review are not from "fatigued muscle"!) For your argument, however, I think you can be assured that your cyclists with delta efficiencies of about 25% are as efficient as can be and that there is not some magic formula (e.g. "technique") that will improve efficiency. You probably know the story that beetroot juice can improve efficiency but demonstration of that effect seems to have required very careful subject selection and a number of other research groups have been unable to replicate the effect. I have recently made another attempt to place some limits of likely efficiency values (see page 989 of attached paper) and concluded that the absolute maximum efficiency of muscle lies between 30 and 35%. The only muscle that approaches these values is the very slow tortoise muscle. Most other muscles studied contract faster than tortoise and also have lower efficiency. I would be quite happy with the idea that the maximum efficiency of human muscle is close to 25%. I hope this helps. Feel free to ask for clarification of any of these points. Chris Chris Barclay School of Allied Health Sciences Griffith University Gold Coast Queensland 4222 Australia "
So can you actually admit that you're wrong for once Frank?”
LOL. Did you forget to show Denis Loiselle Luttrell who demonstrated an improvement in gross efficiency from 20 to 22% in 6 weeks of training to change pedaling technique using the product that shant be named.
And, my claim of 40% efficiency is what is measured in isolated muscle preps on the bench. Chris states the best measure of muscle efficiency is cycling. Wrong! The best measure of muscle efficiency is isolated muscle testing.
Bring them here and lets have a discussion.
Frank Day
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