Gross (Mechanical) Efficiency

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ft_critical
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Gross (Mechanical) Efficiency

Postby ft_critical » Fri Jul 17, 2015 10:56 am

This has been discussed variously on the forum. Here is a great blog from Alex.

http://alex-cycle.blogspot.com.au/2013/ ... tnnw5NQssq

and from the forum
Alex Simmons/RST wrote:There will be a limitation on what's physiologically possible/plausible based on your VO2max, and the ceiling is then a function of your fractional utilisation of VO2max at threshold and your gross efficiency. Physiologically there are a multitude of central and peripheral adaptations required and these changes occurs over days, weeks, months and years. The greatest gains, if consistent and smart with training, come in the first years. They can continue for many years after that but the gains are smaller and harder won, but are often the difference between the best and the also rans.

Of course there are other factors involved with success and that depends on what sort of events you are targeting - skills, tactics, strategy, execution, psychology, experience and so on all contribute to performance beyond power output alone.
In the blog, Alex states that "One thing efficiency is not: it isn't how you pedal, nor the way in which you apply forces to the cranks."

My question, is why is this 'how efficient you are mechanically on the bike' is not captured in the formula [FTP = Energy per litre O2 (J) x VO2max (ml/kg/min) x Fractional VO2max at threshold (%) x GME (%) / 60 (seconds/minute) / 1000 (ml/litre)] (or seemingly irrelevant)?

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Re: Gross (Mechanical) Efficiency

Postby Alex Simmons/RST » Fri Jul 17, 2015 11:48 am

GME is in the formula.

Not sure I quite understand your question. Keep in mind that GME is a measure of energy supplied to the cranks as a proportion of total energy metabolised.

Perhaps you are wondering about what factors influence GME?

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Re: Gross (Mechanical) Efficiency

Postby ft_critical » Fri Jul 17, 2015 11:56 am

One thing efficiency is not: it isn't how you pedal, nor the way in which you apply forces to the cranks.

Why is how you pedal and other mechanical adaptations you make as you develop as a cyclist not included in GME or somewhere else in the formula Alex?

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Re: Gross (Mechanical) Efficiency

Postby Alex Simmons/RST » Fri Jul 17, 2015 3:00 pm

ft_critical wrote:One thing efficiency is not: it isn't how you pedal, nor the way in which you apply forces to the cranks.

Why is how you pedal and other mechanical adaptations you make as you develop as a cyclist not included in GME or somewhere else in the formula Alex?
I think I see the source of confusion. Let me explain my comment which you've quoted.

There are made up metrics, often from power measurement device manufacturers (e.g. power measurement pedals, indoor trainers that measure/display crank torque), that use the term "efficiency" in their metric. e.g. "Pedalling efficiency" or something similar using the word "efficiency". What these measures really relate to is the nature of torque measurements made by the devices (e.g. how even the torque profile is around a pedal stroke, or a ratio of peak to average torque, that sort of thing - there are a number of them).

While they sometimes use the term "efficiency" in their name, they are not measures of efficiency in a physiological or physical sense (which is a ratio of energy output as a proportion of energy input). These terms are misnomers.

If you do things in training and development that:
- raise VO2max, and/or
- raise fractional utilisation of VO2max at threshold, and/or
- raise efficiency

then they clearly are included in the formula.

The questions then become, what influences these three key factors and what training and development activity results in positive adaptations?

You may be surprised to learn that pedalling "technique" training is yet to be shown to do much for any of them, despite numerous studies and all sorts of pedalling intervention inventions over the last century. Indeed varying from one's preferred natural method often has a negative impact.

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Re: Gross (Mechanical) Efficiency

Postby ft_critical » Fri Jul 17, 2015 7:44 pm

Thanks Alex, good answer to my question. A good blog post also, sort of a must read for training.

I have found that efficiency, mechanically, of my body might not be important at a point in time, but my overall mechanical efficiency (not overusing a particular muscle) provides the ability to train more frequently at higher thresholds. It is something I struggle with constantly; evenly distributing work across all my muscles.

Though I am not a track rider, I imagine that starting track as a junior sets you up well in this respect. It is like a basic skill before you even get to the three above. Solid foundation.

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Re: Gross (Mechanical) Efficiency

Postby Alex Simmons/RST » Fri Jul 17, 2015 9:42 pm

That and a bike that's properly fitted for you.

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Re: Gross (Mechanical) Efficiency

Postby MattyK » Thu Jul 23, 2015 2:01 pm

ft_critical wrote:It is something I struggle with constantly; evenly distributing work across all my muscles.
What makes you think this is a good thing? Some of your muscles are naturally stronger and more capable than others, as a result of millions of years of evolution to walking and running. Your natural technique will tend to favour these muscles.

There's a few GCN videos on the topic.

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Re: Gross (Mechanical) Efficiency

Postby ValleyForge » Tue Jul 28, 2015 10:06 am

MattyK wrote:
ft_critical wrote:It is something I struggle with constantly; evenly distributing work across all my muscles.
What makes you think this is a good thing? Some of your muscles are naturally stronger and more capable than others, as a result of millions of years of evolution to walking and running. Your natural technique will tend to favour these muscles.

There's a few GCN videos on the topic.
Absolutely right MK. Certain muscles have mechanical advantage in certain movements, others act as stabilisers. Simple example might be sprinters with well developed upper bodies swinging the bike from side to side using the muscles of the shoulder girdle to gain more power. The muscles are far from ideally mechanically placed to develop power to the pedals efficiently, but they may add a few crucial additional Newtons of forceto the pedals.
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Re: Gross (Mechanical) Efficiency

Postby ft_critical » Fri Jul 31, 2015 6:11 pm

Evenly was misleading. I should better say efficiently, but in the sense of not over relying on my quadriceps as I am trying to correct

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Re: Gross (Mechanical) Efficiency

Postby toolonglegs » Fri Jul 31, 2015 6:27 pm

Quads and butt is what it is all about isn't it? ... coming from someone with 63cm quads vs 41cm calves :oops:

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Re: Gross (Mechanical) Efficiency

Postby ValleyForge » Sat Aug 01, 2015 11:25 am

toolonglegs wrote:Quads and butt is what it is all about isn't it? ... coming from someone with 63cm quads vs 41cm calves :oops:
Many years ago when I joined an invitation-only bunch, the elder statesman sidled up to me and got me in a conversation headlock. He's a vey fit senior road champion and what he loses in years, makes up in craftyness. He asked me what sort of rider was I, and added quickly based on my thighs I would sprint. I didn't quite know how to answer him and ummed &ahhed. He kept badgering me - "come on - not a climber but you've got a climber's bike, domestique..?". I said "phone-support". He nearly fell off laughing. I was in.
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Re: Gross (Mechanical) Efficiency

Postby toolonglegs » Sat Aug 01, 2015 5:30 pm

:lol:
The old dogs know all the tricks :mrgreen:

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Re: Gross (Mechanical) Efficiency

Postby CKinnard » Sat Aug 01, 2015 6:19 pm

one of the most significant things you can do to improve cycling efficiency is not only lose body fat, but as much lean tissue as possible that does not make significant contribution to propelling a bicycle forwards. In doing this, you increase the relative size of the heart's chambers to the rest of the body, and thereby improve blood flow rate to cycling muscle, ergo you get more oxygen to the muscle and better CO2 clearance.

This is what Chris Froome has excelled at, and has helped enormously to improve his power/wt ratio. I don't know of any other top pro who has stripped as much lean tissue off his trunk and upper limbs.

Image

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Re: Gross (Mechanical) Efficiency

Postby Alex Simmons/RST » Sat Aug 01, 2015 9:19 pm

Image

Of course you can always be a chicken...
Image
Although he had other help.
:)

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Re: Gross (Mechanical) Efficiency

Postby ValleyForge » Mon Aug 03, 2015 1:53 pm

CKinnard wrote:one of the most significant things you can do to improve cycling efficiency is not only lose body fat, but as much lean tissue as possible that does not make significant contribution to propelling a bicycle forwards. In doing this, you increase the relative size of the heart's chambers to the rest of the body, and thereby improve blood flow rate to cycling muscle, ergo you get more oxygen to the muscle and better CO2 clearance.
IIRC CO2 clearance is not a limiting factor in exercise. Only where there is significant lung disease or VQ mismatch (ventilation/perfusion). Also there is little reduction in baseline blood flow to non-exercising muscle rather just less weight to accelerate or climb with. However, were are dealing with fractions of a percent at the elite level.

So - improve your O2 uptake and shed weight. For most of us, losing an extra kilo of muscle from our upper body isn't a deal-breaker. Fat, yes; muscle, no.
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Re: Gross (Mechanical) Efficiency

Postby CKinnard » Mon Aug 03, 2015 10:27 pm

ValleyForge wrote:
CKinnard wrote:one of the most significant things you can do to improve cycling efficiency is not only lose body fat, but as much lean tissue as possible that does not make significant contribution to propelling a bicycle forwards. In doing this, you increase the relative size of the heart's chambers to the rest of the body, and thereby improve blood flow rate to cycling muscle, ergo you get more oxygen to the muscle and better CO2 clearance.
IIRC CO2 clearance is not a limiting factor in exercise. Only where there is significant lung disease or VQ mismatch (ventilation/perfusion). Also there is little reduction in baseline blood flow to non-exercising muscle rather just less weight to accelerate or climb with. However, were are dealing with fractions of a percent at the elite level.

So - improve your O2 uptake and shed weight. For most of us, losing an extra kilo of muscle from our upper body isn't a deal-breaker. Fat, yes; muscle, no.
hmmm.... from memory, at higher exercise intensities, lactic acid accumulates due to higher reliance on carbohydrate over fat, which has to be buffered (into CO2), and this can produce 10% more CO2 than oxygen consumed.

re V/Q mismatch, I have it on good authority that Froomey's unique posture on the bike leads to more favorable equal pressure point and physiological dead space.

also, review oxygen tension of the higher climbs in the GTs

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Re: Gross (Mechanical) Efficiency

Postby Alex Simmons/RST » Tue Aug 04, 2015 10:24 am

One of the unfortunate factors at pro level is the use of prohibited substances or medical product abuse to aid the weight loss process. While I don't single out any specific individual pro athlete, I really don't think it helps to suggest to an audience such as on this forum that they approach such things is the manner that pro cyclists do.

Pros can and do go to extremes that may not be ethical, permitted or good for your long term health. Of course they also use strategies that are completely legitimate and can be sensibly applied at amateur/recreational level as well.

Same goes for training - do the training/riding that makes sense for you, not because that's what a pro does.

It's better to consider/apply strategies that are sensible for your individual situation than to follow what a Pro does.

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Re: Gross (Mechanical) Efficiency

Postby ValleyForge » Tue Aug 04, 2015 10:40 am

I didn't see anyone on Le Tour eating kale. :lol:
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Re: Gross (Mechanical) Efficiency

Postby CKinnard » Tue Aug 04, 2015 7:43 pm

Alex Simmons/RST wrote:Pros can and do go to extremes that may not be ethical, permitted or good for your long term health. Of course they also use strategies that are completely legitimate and can be sensibly applied at amateur/recreational level as well.
totally agree. in fact, my esteemed US osteopathic physician mentor advised that the aerodynamic position on a racing bicycle was extremely deleterious to the cervical and lumbar discs and facets joints, and many bodily functions under the control of the autonomic nervous system.....it also compromised cerebrospinal fluid flow between the cranial vault and spinal canal. Recent research reveals anything that impedes such csf flow impairs clearance of metabolic waste from the central nervous system, and thereby increases risk of dementia and accelerated cognitive decline.

I don't doubt that 100 years from now, people will look back with bemusement at the highly unnatural extremes people went to to go slightly faster on a bicycle, for no good reason other than recreational pleasure.

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Re: Gross (Mechanical) Efficiency

Postby CKinnard » Tue Aug 04, 2015 7:53 pm

ValleyForge wrote:I didn't see anyone on Le Tour eating kale. :lol:
what did you see them eating?

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Re: Gross (Mechanical) Efficiency

Postby Alex Simmons/RST » Tue Aug 04, 2015 8:37 pm

CKinnard wrote:
Alex Simmons/RST wrote:Pros can and do go to extremes that may not be ethical, permitted or good for your long term health. Of course they also use strategies that are completely legitimate and can be sensibly applied at amateur/recreational level as well.
totally agree. in fact, my esteemed US osteopathic physician mentor advised that the aerodynamic position on a racing bicycle was extremely deleterious to the cervical and lumbar discs and facets joints, and many bodily functions under the control of the autonomic nervous system.....it also compromised cerebrospinal fluid flow between the cranial vault and spinal canal. Recent research reveals anything that impedes such csf flow impairs clearance of metabolic waste from the central nervous system, and thereby increases risk of dementia and accelerated cognitive decline.

I don't doubt that 100 years from now, people will look back with bemusement at the highly unnatural extremes people went to to go slightly faster on a bicycle, for no good reason other than recreational pleasure.
Does your mate have some actual evidence on cyclists to back up his hypothesis?

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Re: Gross (Mechanical) Efficiency

Postby NeillS » Tue Aug 04, 2015 8:46 pm

Yeah I'm with Alex on this one, that sounds like rubbish.

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Re: Gross (Mechanical) Efficiency

Postby CKinnard » Tue Aug 04, 2015 9:05 pm

Alex Simmons/RST wrote:
CKinnard wrote:
Alex Simmons/RST wrote:Pros can and do go to extremes that may not be ethical, permitted or good for your long term health. Of course they also use strategies that are completely legitimate and can be sensibly applied at amateur/recreational level as well.
totally agree. in fact, my esteemed US osteopathic physician mentor advised that the aerodynamic position on a racing bicycle was extremely deleterious to the cervical and lumbar discs and facets joints, and many bodily functions under the control of the autonomic nervous system.....it also compromised cerebrospinal fluid flow between the cranial vault and spinal canal. Recent research reveals anything that impedes such csf flow impairs clearance of metabolic waste from the central nervous system, and thereby increases risk of dementia and accelerated cognitive decline.

I don't doubt that 100 years from now, people will look back with bemusement at the highly unnatural extremes people went to to go slightly faster on a bicycle, for no good reason other than recreational pleasure.
Does your mate have some actual evidence on cyclists to back up his hypothesis?
actual evidence is an interesting thing isn't it.
there's no actual evidence poor posture predisposes to herniated lumbar discs.
I suppose one's grasp of science determines what level of evidence they need to accept or refute a position not specifically subjected to a randomized controlled trial.

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Re: Gross (Mechanical) Efficiency

Postby Alex Simmons/RST » Wed Aug 05, 2015 8:04 am

CKinnard wrote:actual evidence is an interesting thing isn't it.
there's no actual evidence poor posture predisposes to herniated lumbar discs.
If a complete lack of evidence really is the case, then it is reasonable to question the premise.
CKinnard wrote:I suppose one's grasp of science determines what level of evidence they need to accept or refute a position not specifically subjected to a randomized controlled trial.
Indeed, and the better you grasp science the more you recognise that claims made without at least some sound evidence/rationale to support them should be questioned.

This is (was) a thread about cycling efficiency.

You then pop up and suggest aerodynamic bike positions may be a cause of dementia. I think that's an extraordinary claim. And you know what they say about extraordinary claims.

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