Author Topic: Sucking the joy out of walking  (Read 1835 times)

WhitstableDave

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Re: Sucking the joy out of walking
« Reply #15 on: 18:28:40, 12/07/20 »
I did an experiment yesterday.  :)

I walked at a steady 4.5mph with 0% incline on my treadmill and saw that the estimated energy expenditure was 510 Calories per hour.

I raised the incline to 10% and reduced the speed until the est. energy expenditure was 510 Calories per hour. That happened at exactly 3.2 mph.

Therefore, (on a treadmill) walking at 3.2mph up a 10% incline is equivalent (in terms of work done) to walking at 4.5mph on the level.

For those who can't be bothered to work it out, walking for 10 miles up a 10% incline would give an ascent of approx. 5,280ft - or a fair amount!

It might then be argued that, under ideal conditions, walking for 10 miles at 4.5mph would be as demanding as ascending 5,280ft at 3.2mph.

Does that count as sucking the joy out of walking?  ;)


 



Bigfoot_Mike

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Re: Sucking the joy out of walking
« Reply #16 on: 18:46:55, 12/07/20 »
I did an experiment yesterday.  :)

I walked at a steady 4.5mph with 0% incline on my treadmill and saw that the estimated energy expenditure was 510 Calories per hour.

I raised the incline to 10% and reduced the speed until the est. energy expenditure was 510 Calories per hour. That happened at exactly 3.2 mph.

Therefore, (on a treadmill) walking at 3.2mph up a 10% incline is equivalent (in terms of work done) to walking at 4.5mph on the level.

For those who can't be bothered to work it out, walking for 10 miles up a 10% incline would give an ascent of approx. 5,280ft - or a fair amount!

It might then be argued that, under ideal conditions, walking for 10 miles at 4.5mph would be as demanding as ascending 5,280ft at 3.2mph.

Does that count as sucking the joy out of walking?  ;)
That all depends upon how the estimated energy expenditure is calculated and if there is any accuracy in the measure. A 10% slope is almost flat for hill walkers  :)

ninthace

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Re: Sucking the joy out of walking
« Reply #17 on: 19:02:52, 12/07/20 »
Gentlemen - a bit of trigonometry and some simple Mechanics will tell you the work done moving a mass through a horizontal distance as opposed to carrying it up a slope of given gradient for the same distance which will be the work required to move the mass a shorter horizontal distance plus the work required to lift it vertically to the top of the slope (this where the trig comes in).


The rest is friction.



I am off to cook my tea - I am sure you will have it done by the time I have washed up.  O0
« Last Edit: 19:31:49, 12/07/20 by ninthace »
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Mel

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Re: Sucking the joy out of walking
« Reply #18 on: 19:18:09, 12/07/20 »
Well I'm intrigued, what is the 'Parent (MA) bit about and why is it on the High Street? Also why is the catchment in Kent?


Blind stab in the dark...


High Street (the Parent hill) is a (Ma)rylin.


Water flows off the hill into the River Kent.






I've no idea if/why anyone would iron their underpants.







Is the search over if you find nothing?
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richardh1905

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Re: Sucking the joy out of walking
« Reply #19 on: 19:19:08, 12/07/20 »
Gentlemen - a bit of trigonometry and some simple Mechanics will tell you the work done moving a mass through a horizontal distance as opposed to carrying it up a slope of given gradient for the same distance whicj will be the work required to move the mass a shorter horizontal distance plus the work required to lift it vertically to the top of the slope (this where the trig comes in).

The rest is friction.

I am off to cook my tea - I am sure you will have it done by the time I have washed up.  O0


Sometimes I wish that there was a 'like' button on this forum  O0
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richardh1905

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Re: Sucking the joy out of walking
« Reply #20 on: 19:20:23, 12/07/20 »
Does that count as sucking the joy out of walking?  ;)


YES  ;)
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ninthace

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Re: Sucking the joy out of walking
« Reply #21 on: 19:44:57, 12/07/20 »

Sometimes I wish that there was a 'like' button on this forum  O0
Are you going to be the one to point out how fast you go along or up has no bearing on the amount of work done?
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pleb

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Re: Sucking the joy out of walking
« Reply #22 on: 19:50:46, 12/07/20 »
Its Schrodingers "like" button...
Well-meaning old fart.

richardh1905

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Re: Sucking the joy out of walking
« Reply #23 on: 21:15:24, 12/07/20 »
Are you going to be the one to point out how fast you go along or up has no bearing on the amount of work done?


I'll let others work that out for themselves  ;)
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WhitstableDave

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Re: Sucking the joy out of walking
« Reply #24 on: 22:25:52, 12/07/20 »
Are you going to be the one to point out how fast you go along or up has no bearing on the amount of work done?

Hmm... I made it clear in the first two lines that the speed and ascent were related to energy expenditure, which I clearly gave in Calories per hour.

Calories per hour is a measure of power or rate of doing work. It is not a measure of work done.

I admit to being careless in the third line where I put: 'in terms of work done' in brackets. I should written 'in terms of rate of work done'.

Having said all that, I'm surprised you believe that neither speed nor ascent have a bearing on the amount of work done. As I understand it, walking involves movement of the body's centre of mass (in a sort of figure of 8 motion). The CoM moves because muscles provide the forces to accelerate and decelerate the mass. Put simply, work is done on the body's CoM in order to create a walking motion.

In addition to muscles doing work on the CoM, walking requires other muscles (such as those acting on the ankles) to provide forward motion. Also, friction in joints and other areas of the body needs to be overcome.

I do get that you'd probably have gained a tick in a CSE Physics exam, but real life tends to be more complicated. In real life, the body uses more energy per hour and therefore does more work per hour the faster you go. But I expect you meant to put 'total' before 'work done'. If so, then you'd be correct (at CSE level) to point out that when a body moves with no change in elevation from A to B (i.e. 'go along') that no work has been done at all since the energy state of the body remains unchanged. But that would require a frictionless world in which muscles do not create more heat (use more energy) the harder they do work in order to move the body faster. 

A thought experiment: Imaging driving a car at a steady 50mph to a height of (say) 1000ft and noting the mount of fuel used (energy used being equivalent to work done). Now imagine doing the same trip at 70mph (after refilling the tank!). Would you expect more fuel to have been used on the second trip than on the first (assuming the car coped well at both speeds in the same gear)? If more fuel was required, then more energy was required, and therefore more work was done. It just didn't all end up increasing the car's potential energy.
« Last Edit: 22:31:39, 12/07/20 by WhitstableDave »

Theo Frum

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Re: Sucking the joy out of walking
« Reply #25 on: 23:01:28, 12/07/20 »
I did an experiment yesterday.  :)

I walked at a steady 4.5mph with 0% incline on my treadmill and saw that the estimated energy expenditure was 510 Calories per hour.

I raised the incline to 10% and reduced the speed until the est. energy expenditure was 510 Calories per hour. That happened at exactly 3.2 mph.

Therefore, (on a treadmill) walking at 3.2mph up a 10% incline is equivalent (in terms of work done) to walking at 4.5mph on the level.

For those who can't be bothered to work it out, walking for 10 miles up a 10% incline would give an ascent of approx. 5,280ft - or a fair amount!

It might then be argued that, under ideal conditions, walking for 10 miles at 4.5mph would be as demanding as ascending 5,280ft at 3.2mph.

Does that count as sucking the joy out of walking?  ;)


Data from one of my Bruce tests:



ninthace

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Re: Sucking the joy out of walking
« Reply #26 on: 01:01:36, 13/07/20 »
<<snip>>



A thought experiment: Imaging driving a car at a steady 50mph to a height of (say) 1000ft and noting the mount of fuel used (energy used being equivalent to work done). Now imagine doing the same trip at 70mph (after refilling the tank!). Would you expect more fuel to have been used on the second trip than on the first (assuming the car coped well at both speeds in the same gear)? If more fuel was required, then more energy was required, and therefore more work was done. It just didn't all end up increasing the car's potential energy.
Actually I would say the same amount of work was done.  Work done is basically force times distance. If the car is raised to the same height, the same work is done.  In the second instance, it is just done less efficiently so more energy is used but the gain in potential energy is the same.


In my day it was an O-level GCE Physics. CSEs were what people who went to secondary modern schools usually did.  O0   I was using Mechanics though in my example of horizontal movement and vertical lifting.
« Last Edit: 01:45:01, 13/07/20 by ninthace »
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Bigfoot_Mike

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Re: Sucking the joy out of walking
« Reply #27 on: 06:40:27, 13/07/20 »
The efficiency of the human body is not necessarily constant with speed and gradient. Body posture and gait changes , as does the method of energy usage. Friction (including air resistance) is not linear with speed. More energy will be lost as heat (and potentially sound) under higher exertion levels. More energy will be used accelerating to higher speeds (kinetic energy is proportional to the square of velocity). In any event, I assume there are very few walkers who determine their speed and distance to match an energy target produced by some dodgy calculations generated by technology. My Fitbit estimated that I expended much less energy swimming breast stroke for 90 minutes than I did walking on the flat for a similar amount of time. It certainly didnít feel that way.

watershed

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Re: Sucking the joy out of walking
« Reply #28 on: 07:24:40, 13/07/20 »
I Don’t know if these observations are relevant to this thread but here are my 2 pennies worth.
I find that the limiting factor for me with speed when walking on relatively flat surfaces is a combination of my stride length and leg cadence. I find that when wearing boots on the road if I don’t stop to speak to people, take photos etc If I am pushing on it is @ 4.3-4.4mph.
Interestingly aerobically I am not stressed at this speed.
To go much quicker I would need to either wear shoes, not carry a rucksack and/or change leg speed and cadence by starting to jog. If I went much quicker walking, I fear I might start mincing.
To go even quicker I would need to run, cycle, or take the car.
When in the hills the limiting factors are ground conditions (heather, mud, rocky, sandy, river crossings, etc), How hilly, weight of rucksack, views to stop for etc.
In these walks I am often challenged Aerobically when walking at less than even 2-3mph.
In the past, on relatively flat say 10 milers to be challenged aerobically when running, I would need to be moving at nearer 12 mph, Where as when running cross country it would occur at @10mph, but that is for a different forum.

Birdman

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Re: Sucking the joy out of walking
« Reply #29 on: 13:02:37, 13/07/20 »
For me, energy expenditure is mainly dependant on how good the ground is under foot. Climbing a hill with moderate rate of ascend on an excellent trail (flat under the foot, no loose stones etc) is less tiring than a trail that doesn't climb but has many loose rocks etc.
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