energy required to clmb a hil....
Comments
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YIMan wrote:It is not linear but for cyclists the relative power difference is negligible compared to the energy required to get up the hill - assuming one rider isn't doing 6 times the speed of the other. And assuming there isn't a huge headwind....or if there's a tailwind the minimal effect is reduced further.
True, but then you're the one arguing the toss over how much energy is used converting food to usable energy. If you're going to argue over a watt or two, at least be consistent.0 -
Froomes Edgar wrote:
Nice pic.0 -
diy wrote:there are two parts to the question.
1. two riders of same weight, speed etc. will require the same energy to get to the top irrelevant of fitness.
2. two riders of different fitness (but same weight speed etc) will have different requirements to output that energy.
1) Yes, I believe so, or at least there's no significant "overcoming air resistance" difference for cyclists at normal uphill speeds
2) Yes, I believe so......but I think the debate is around how big a difference this is.....it could be just as negligible as the air resistance.....it could be huge......no-one's really had any idea so far.
If both factors are equally negligible, it could be there is not difference in the energy required, it's just that
a) The fitter cyclist has a greater power output capability and can ride up the hill faster in the first place
and
b) The fitter/trained cyclist has the physical capacity to do the hill repeatedly, whereas an unfit cyclist may be finished after riding up the hill once at a slow speed.0 -
Froomes Edgar wrote:Maths pet peeve - its not exponential. Power vs speed is cubic.
I'm glad I have made this valuable and absolutely necessary correction.
you'll be familiar with Einstein's theory of special relativity then
but back on topic.
I'm still not convinced that the differences between a fit person and an unfit person are so trivial. The whole argument behind interval and sprint training. good summary here: http://www.pponline.co.uk/encyc/0129.htm0 -
YIMan wrote:diy wrote:there are two parts to the question.
1. two riders of same weight, speed etc. will require the same energy to get to the top irrelevant of fitness.
2. two riders of different fitness (but same weight speed etc) will have different requirements to output that energy.
1) Yes, I believe so, or at least there's no significant "overcoming air resistance" difference for cyclists at normal uphill speeds
2) Yes, I believe so......but I think the debate is around how big a difference this is.....it could be just as negligible as the air resistance.....it could be huge......no-one's really had any idea so far.
If both factors are equally negligible, it could be there is not difference in the energy required, it's just that
a) The fitter cyclist has a greater power output capability and can ride up the hill faster in the first place
and
b) The fitter/trained cyclist has the physical capacity to do the hill repeatedly, whereas an unfit cyclist may be finished after riding up the hill once at a slow speed.
I think we do have an idea of the extra wattage required by an average cyclist v pro cyclist just to take account of less developed cardio system. Heart at full gas requires 2W to operate. No idea about diaphragm muscles but let's guess the same. Even if the pro cyclist heart and breathing rates were half the average cyclist, this would only have a 2W effect
I could work out the wind resistance effect in watts but I'm half way thru a bottle of wine. Suffice to say it's a lot more than 2W0 -
Yep, that's what efficiency is: the ability to use delivered energy (via the bloodstream) completely by the cell for each delivered heart stroke. It's like an untrained athlete blows fuel out via the exhaust pipe and a trained athlete uses it all.rstabler11 wrote:I don't think having more / a higher density of mitochondria should make a difference, shouldn't it just mean you can convert more food into more energy, but not change efficiency? If, however, you can change efficiency of mitochondria that would be significant. I'm not sure though.
BTW if you do want to see any primary papers PM me which ones and I might well be able to get you the pdf on my uni access0 -
The guy whose done the most HIT training wins..........................the deeper the section the deeper the pleasure.0
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Froomes Edgar wrote:diy wrote:I don't think we have even established that everyone can convert food to output equally. I think all that has been shown is that for a given amount of processed fuel (cell level) and oxygen, we have broadly the same ability to convert that in to muscle movement and output. Seems logical, but its only the very last part of the chemical process.
Well that's beyond the scope of a cycling forum, and the question at hand, I'd suggest. But since the average (sedentary) bloke requires in the region of 2,500 calories per day to take care of food digestion as well as all other bodily processes, and cycling at a chippertastic 250w up a big hill requires about 1,000 per hour, I'd question whether we're straying into the grounds of immateriality again.
The mitochondria stuff - yes, increasing mitochondrial density is a known adaptation to aerobic exercise and is one of the components of Froome's bigger (as compared to the chipper) engine. Doesn't say anywhere that conversion form fat is more efficient than from glycogen though (it might well be BTW, I don't know). Would contradict the finding that efficiency doesn't vary much if so.
This has gone too far. No-one knows what they're talking about, including me.
The efficiency of converting food into energy by the mitochondria doesn't change, the efficiency of he digestive tract into converting mars bars into small useful molecules doesn't change, what changes is the volume of blood (stroke volume), and the amount of mitochondria (engine size). An untrained rider doesn't get the same volume of blood supplied to his working muscles and cannot use he given amount of glucose supplied by the blood ( less mitochondria).
It's a little similar ( by analogy) to a 4stroke carburettor engine compared to a modern fuel injected v8,but both running on the same premium fuel. The energy required to get to to he top of the hill is the same, the modern engine can do it much faster.
Where the analogy falls down is that in the body the fuel delivery system is circular and unused fuel (glucose) and exhaust products ( co2) are not blown out the exhaust, but recycled through the system (where wastes are removed and unused glucose has to be pumped back around{ losing efficiency}). this points to the efficiency gains created by he fit guy, more complete burning of delivered fuel For every heart stroke. There's more stuff going on but this is a simplistic and as much as I can remember from bioscience.0 -
nickyboy zz wrote:YIMan wrote:diy wrote:there are two parts to the question.
1. two riders of same weight, speed etc. will require the same energy to get to the top irrelevant of fitness.
2. two riders of different fitness (but same weight speed etc) will have different requirements to output that energy.
1) Yes, I believe so, or at least there's no significant "overcoming air resistance" difference for cyclists at normal uphill speeds
2) Yes, I believe so......but I think the debate is around how big a difference this is.....it could be just as negligible as the air resistance.....it could be huge......no-one's really had any idea so far.
If both factors are equally negligible, it could be there is not difference in the energy required, it's just that
a) The fitter cyclist has a greater power output capability and can ride up the hill faster in the first place
and
b) The fitter/trained cyclist has the physical capacity to do the hill repeatedly, whereas an unfit cyclist may be finished after riding up the hill once at a slow speed.
I think we do have an idea of the extra wattage required by an average cyclist v pro cyclist just to take account of less developed cardio system. Heart at full gas requires 2W to operate. No idea about diaphragm muscles but let's guess the same. Even if the pro cyclist heart and breathing rates were half the average cyclist, this would only have a 2W effect
I could work out the wind resistance effect in watts but I'm half way thru a bottle of wine. Suffice to say it's a lot more than 2W
Ok...that's the heart....what about the effect of the rest of the body's physiology/efficiency?
I did find this, so assuming its calculations are correct:
http://www.exploratorium.edu/cycling/aerodynamics1.html
Using this:
180lb rider riding up a 8% slope, no wind, at 10mph = 7.31 calories per minutes energy required
A rider of the same weight but MUCH less fit so let's say doing only 5mph = 3.6 calories per minute
So if the 5mph rider were capable of going twice as fast you'd expect him to expend 7.2 calories per minute. So the delta that "air resistance" makes is 0.31 calories per minute.....i.e. negligible compared to the overall energy required just to get up the hill.
Obviously the faster they go the more air resistance comes into play, but I am assuming people don't climb proper hills at 20mph.0 -
So much broscience in this thread...0
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I thing the fundamentals of the second part of the question is what differences are occurring in the fit riders body vs the unfit riders body. Nothing else is really going to make a difference.
its going to be things like:
- cycling efficiency - was lucky enough to be inches away from cav on a big climb - stone cold face, no movement whatsoever apart from his legs.
- biological efficiency - the impact of training on the body which will physically change the fit riders body and tune him to the job. This will be right down to a cellular and chemical level
- Metabolic efficiency - The ability of the fit person to turn food in to fuel.
- Cardiovascular efficiency - The efficiency of the o2 delivery system.
In all these areas I think we'll find substantial differences between the two riders.0 -
Haven't read all of this thread, but if you want to calculate the power needed to climb a hill given a certain speed, or speed given a certain power (taking into account all significant non-biological factors such as air resistance, rolling resistance etc), you can do it here:
http://analyticcycling.com/DiffEqMotion ... _Page.html
Hit the "tool kit" button on the right, then pick "static forces on rider", and either "power, given speed" or "speed, given power". Alex Simmons on the training forum told me the best estimates for the physical parameters to enter for your average climbing contitions - about 0.35 for effective frontal area, 1 for drag coefficient and 0.005 for rolling resistance. You also need total weight of rider, bike and gear (don't forget to add about 2kg for your shoes, clothes, helmet etc..). For slope, enter the average for the climb in decimal, e.g. a 6% average slope is 0.06. If you are calculating power you will need to enter speed in meters per second - so, e.g., if you took 50mins to climb 13km that's 13000 meters in 50 x 60 seconds, = 4.33 m/s.
So that will give you the average power-to-the-pedals required to do the climb at at a certain speed. You can directly convert power to kilojoules per hour, and then use the time taken to calculate the total amount of energy used to turn the pedals in kilojoules.
BUT... You actually expend far more energy when you are exercising than you are able to put into the pedals, because you are not very efficient and most energy you burn is converted into heat... For a fit person, the total amount of energy expended is about 4 times the amount converted into external power, while for an unfit person it might be 5-6(?) times. There is also energy lost through pedalling efficiency, etc.
So a fit person will be able to put out more power (and so more energy over a certain time period) and will thus climb the hill faster, but he will ALSO be slightly more efficient in converting the energy he is burning into motion, through metabiolic and mechanical efficiency etc. So he will either use more energy to climb the hill and climb it faster, or if he slows down and climbs it at the same speed as a less fit person of the same weight, he will use slightly less energy to do so.0 -
Do we have any evidence for and/or quantification of this possible higher efficiency of the fitter rider? Thought not.0
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Ok, it seems to be controversial.Froomes Edgar wrote:Do we have any evidence for and/or quantification of this possible higher efficiency of the fitter rider? Thought not.
There are certainly differences in efficiency between individuals (up to 30%), but it's controversial how much this is due to fitness (history of training) or to other factors, e.g. see:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1805795/0 -
I've yet to see any evidence presented that this basic common sense of a fitter rider being more efficient doesn't exist.
But then I used the ignore button some time ago.
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YIMan wrote:I've yet to see any evidence presented that this basic common sense of a fitter rider being more efficient doesn't exist.
But then I used the ignore button some time ago.
Well done. Argue on the internet, but ignore anyone who disagrees with you.0 -
I really regret being offline for a few hours, this is so much fun! Unfortunately I am now in Amsterdam airport waiting for a connecting flight and am half cut already so please bear with me
Re air resistance, thanks for doing the calcs for me! I was half cut last night so couldn't (there is a worrying trend developing here it seems). Anyway, seems we all agree that the wind resistance effect (albeit small compared to total Watts required to climb) is quite a bit more than the effect of faster heartbeat, faster respiration etc etc
But let's cut out the common sense stuff. Just do the science. There may (or may not) be some link between training and the body's efficiency in converting energy into work. Until that's clear, let's assume that there is not effect. Despite how un-common sense that seems
Now, where's that zinfandel.....0 -
nickyboy zz wrote:I really regret being offline for a few hours, this is so much fun! Unfortunately I am now in Amsterdam airport waiting for a connecting flight and am half cut already so please bear with me
Re air resistance, thanks for doing the calcs for me! I was half cut last night so couldn't (there is a worrying trend developing here it seems). Anyway, seems we all agree that the wind resistance effect (albeit small compared to total Watts required to climb) is quite a bit more than the effect of faster heartbeat, faster respiration etc etc
But let's cut out the common sense stuff. Just do the science. There may (or may not) be some link between training and the body's efficiency in converting energy into work. Until that's clear, let's assume that there is not effect. Despite how un-common sense that seems
Now, where's that zinfandel.....
Excellent, arguments from a drunken idiot0 -
ShutUpLegs wrote:nickyboy zz wrote:I really regret being offline for a few hours, this is so much fun! Unfortunately I am now in Amsterdam airport waiting for a connecting flight and am half cut already so please bear with me
Re air resistance, thanks for doing the calcs for me! I was half cut last night so couldn't (there is a worrying trend developing here it seems). Anyway, seems we all agree that the wind resistance effect (albeit small compared to total Watts required to climb) is quite a bit more than the effect of faster heartbeat, faster respiration etc etc
But let's cut out the common sense stuff. Just do the science. There may (or may not) be some link between training and the body's efficiency in converting energy into work. Until that's clear, let's assume that there is not effect. Despite how un-common sense that seems
Now, where's that zinfandel.....
Excellent, arguments from a drunken idiot
I'm happy to take the drunken bit of your insult so long as you hang on to the idiot bit. You seem well suited0 -
ShutUpLegs wrote:Excellent, arguments from a drunken idiot
To be fair, that puts him in the top 5% of BikeRadar.0 -
Froomes Edgar wrote:ShutUpLegs wrote:Excellent, arguments from a drunken idiot
To be fair, that puts him in the top 5% of BikeRadar.
Actually Idiots classify below Morons and Imbeciles on the old official nomenclature. I'm hurt, I thought I would at least classify as an Imbecile0 -
neeb wrote:
Well, that article I linked to above appears to do exactly that..YIMan wrote:I've yet to see any evidence presented that this basic common sense of a fitter rider being more efficient doesn't exist.
Although you could probably present evidence for the other argument too.
My comment wasn't aimed at you, it was for the now invisible nuisances who have added nothing to this discussion but snide comments and insults.....and think that's ok because that's just what everyone does on the Internet.0 -
Something else I thought of actually - let's say the two riders ascend at the same speed and that physiological efficiency differences are negligible. The fitter rider is cruising and the less fit rider is at his limits.
During the climb the energy expended is exactly the same.....but after the climb the less fit rider will burn many more calories as his body recovers from the exertion and expends energy into repairing and "upgrading" his body?0 -
I assume that the two riders are same weight. Certainly they will experience different training loads, because they will have been working at different percentages of their maximum capacities (say different percentages of their functional threshold power, or FTP). The less fit rider will indeed require more recovery and may gain more benefits from it in terms of fitness. Probably this will involve the burning of more energy afterwards, but I have no idea how much...YIMan wrote:Something else I thought of actually - let's say the two riders ascend at the same speed and that physiological efficiency differences are negligible. The fitter rider is cruising and the less fit rider is at his limits.
During the climb the energy expended is exactly the same.....but after the climb the less fit rider will burn many more calories as his body recovers from the exertion and expends energy into repairing and "upgrading" his body?0 -
YIMan wrote:Something else I thought of actually - let's say the two riders ascend at the same speed and that physiological efficiency differences are negligible. The fitter rider is cruising and the less fit rider is at his limits.
During the climb the energy expended is exactly the same.....but after the climb the less fit rider will burn many more calories as his body recovers from the exertion and expends energy into repairing and "upgrading" his body?
Jesus wept. You can make up any sh!te you like - proving it is the tricky bit.0 -
Methinks we have maybe exhausted this thread even more than the fat kid trying to climb Alp D huez!!!!!0
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Yep. There's always some muppet who makes something up then says "but you can't prove its not true".
Besides, unless Alex or Ric show up, we're not going to get anywhere.0 -
You could read my comments earlier, most efficiency gains are produced by using more of the available o2and glucose that the heart can deliver with each stroke. There's many other factors, such as increased blood volume, myoglobin content in muscles, mitochondrial density, increased blood delivery, clearance of waste products etc.not all of which are efficiency gains per se, more quantitative gains in energy utilisation. But as this means less recycling of energy substrates per heart beat, these technically are additive to overall efficiency.Froomes Edgar wrote:Do we have any evidence for and/or quantification of this possible higher efficiency of the fitter rider? Thought not.
It's pretty obvious that a trained cyclist is more efficient, biomechanically or metabolically -how else do you explain the value of training in light of the principle of conservation of energy?
Where these efficiencies lie is the province of physiological effects of training and the mechanical/neuromotor gains, ain't no mystery.
If you want to know what degree of efficiency is gained:can't help you.0 -
Wily-Quixote wrote:
You could read my comments earlier, most efficiency gains are produced by using more of the available o2and glucose that the heart can deliver with each stroke. There's many other factors, such as increased blood volume, myoglobin content in muscles, mitochondrial density, increased blood delivery, clearance of waste products etc.not all of which are efficiency gains per se, more quantitative gains in energy utilisation. But as this means less recycling of energy substrates per heart beat, these technically are additive to overall efficiency.Froomes Edgar wrote:Do we have any evidence for and/or quantification of this possible higher efficiency of the fitter rider? Thought not.
Yeah, I did read and it was interesting - thanksWily-Quixote wrote:It's pretty obvious that a trained cyclist is more efficient, biomechanically or metabolically -how else do you explain the value of training in light of the principle of conservation of energy?
The same way I would explain the fact that a Ferrari is faster than a Toyota Yaris. It has a bigger engine and can use more fuel. Doesn't necessarily follow that the Ferrari is more efficient.Wily-Quixote wrote:Where these efficiencies lie is the province of physiological effects of training and the mechanical/neuromotor gains, ain't no mystery.
If you want to know what degree of efficiency is gained:can't help you.
That's the key really. If its one or two watts, who cares? If its 20 or 30, then also who cares? Strangely, me.0
