Turbo Session v Road miles

amaferanga

Chiggy wrote:

P_Tucker wrote:

Chiggy wrote:

The ONLY way you can observe and record "Intensity" of human activity is to firstly measure the O2 and CO2 content of the ambient air, and secondly, measure the O2 and CO2 content of the poor chap's exhaled breath.

Try doing that on a road ride without a truck full of gas analysers..

So what's a powermeter then?

A powermeter is a dynamometer. It measures the power generated by the engine either at the crank, at the hub or at the roller.
In an engine test cell, the dynamometer is measuring the power generated by the engine. The engine will NEVER get to its full potential if you continuously swill freezing cold water through the cylinder head and not allow it to warm up to normal operating temperature.

On a Turbo trainer or ergometer, the rider will NEVER get to his/her full potential if he/she has freezing cold air blasing on his/her legs and ribcage throughout the test.

On an indoor Turbo, the room's ambient air and therefore the rider's skin temperature can be controlled to be the same at every test. On the road, it can't.

The purpose of a turbo trainer is to quantify any improvement in performance. This is done realistically with two O2 and CO2 analysers. These directly measure the rider's VO2 uptake and operates by the 'Carbon balance' theory of combustion efficiency.
If the cyclist uses the same equipment with every test, the turbo's powercurve is known, and the bike remains close to constant, AND SO DO THE ATMOSPHERIC CONDITIONS, so a faster speed with less VO2 indicates a more efficient engine. A powermeter merely confirms the fact.

In an engine test cell, intake air, exhaust gas AND fuel flow are measured as well as power output. On a cyclist on a turbo, it is difficult to measure fuel flow, so O2 and CO2 are used to calculate fuel usage for the power output.

Without knowing the balance of CO2 and O2, the research engineer can but guess the intensity of the rider's session.

Does that explain it better?

That's all very uninteresting, but you haven't explained why a powermeter is not a useful gauge of intensity and useful for assessing improvement? It measures work done by the human body after all....

Chiggy

The powermeter ( dynamometer ) only measures PART of the work done by the body.

To be of any use, the other energy expulsion routes have to be consistant and repeatable from test to test.

The other energy expulsion routes are Thermal. A person's VO2 uptake has to take care of ALL power generation and body temperature stabilisation work.
When the body's system is called to work more on keeping the skin warm, muscular power in the legs is sacrificed.

amaferanga

Chiggy wrote:

The powermeter ( dynamometer ) only measures PART of the work done by the body.

To be of any use, the other energy expulsion routes have to be consistant and repeatable from test to test.

The other energy expulsion routes are Thermal. A person's VO2 uptake has to take care of ALL power generation and body temperature stabilisation work.
When the body's system is called to work more on keeping the skin warm, muscular power in the legs is sacrificed.

So assuming a moderate winter temperature of say 5 degrees Celsius, how much work is done over an hour keeping a cyclist warm (assuming that they're wearing appropriate clothing) compared to the work they expend cycling at say 200 Watts? How much different would the work done keeping warm/stabilising body temperature be if it were 0 degrees or -5 degrees or +20 degrees (again assuming that appropriate clothing is being worn)? If they're wearing appropriate clothing then I'd say that the work done stabilising temperature is negligible compared to the work done turning the cranks.

I think you're making this sound much more complicated than it actually is.

jibberjim

amaferanga wrote:

I think you're making this sound much more complicated than it actually is.

He's also ignoring the fact that cycling indoors on a turbo and cycling outdoorson the road are different activities so if we assume what we care about is measuring changes in fitness at cycling on roads. Then measuring what happens on a turbo is kind of pointless as changes could simply come from improvements in turbo efficiency and no overall change or even a decline in outdoor cycling performance.

But it's Chiggy so we don't really need to worry about it, just enjoy.

Chiggy

Everyone and their dog should know the human being is somewhere between 20 and 30% efficient.
This means the amount of kCals used for 'Tractive' motion is about a quarter of all the calories burned.

In ideal conditions where ambient air close to the body under clothing is 33 C, the same as Neutral Skin Temperature, the cyclist's efficiency will be greatest, as there is energy lost trying to keep cool as well.

This 'ideal condition' efficiency might be as high as 30%!!

So in answer to your question, the energy lost through thermal routes is about twice as much as what gets to the tyre road interface.

My model of a five hour Audax 100 at 20 C shows 1.1 kCals/min tractive and 4.8 kCals/min thermal. So when I do an Audax 100 at 20 kmh average, I'm just under 23% efficient. Which is OK because they are 'weight loss' sessions.

Anyway; The purpose of an indoor trainer is to flog yourself to lose fat, build strength and improve endurance, so you want efficiency to be low.

amaferanga

I often wonder who you're debating with Chiggy and how much of what you write is misinterpreted from Wikipedia....

So now you're telling us that 70% of calorie expenditure goes on regulating body temperature?

secretsqizz

You are debating with Bhima's dad.

rich164h

amaferanga wrote:

So now you're telling us that 70% of calorie expenditure goes on regulating body temperature?

Sounds about right to me. someone that does zero exercise still needs thousands of calories everyday just to survive and that's in the case where they are in normal indoor environments where there aren't extreme temperature gradients to cope with. Compare that to the calorie intake of someone that exercises regularly and there isn't a huge difference.

Think about it, you've got a mass that's, I don't know, 70-100kg for a male that need to be kept 10-20 degrees above the ambient air temperature at all times. Do you really think that this takes a small amount of energy to do that? Imagine a pot with 100 litres of water in it, to keep that elevated by 20 degrees you'd probably need to constantly have a gas burner underneath it.

Anyway; The purpose of an indoor trainer is to flog yourself to lose fat, build strength and improve endurance, so you want efficiency to be low.

I'm not sure that's right though is it? surely all you want is for there to be a high overall power usage. How efficient the use is is irrelivent.

amaferanga

70% on regulating body temperature or 70% on maintaining normal bodily function?

rich164h

I'd say that most of the internal energy is spent on temperature control, but the two things aren't seperate. Many of the normal bodily functions only happen because the temperature conditions allow it to.

I'd also say that 70% is probably a ball park figure anyway so whether the 70% is actually 65% heat and 5% other things, or 70% heat and 75% including other things is neither here nor there.

I'm a scientist but not a medical professional so I stand to be corrected on any of the above.I'm just looking at it from a physics/engineering point of view (with a touch of chemistry thrown in)

jibberjim

rich164h wrote:

amaferanga wrote:

So now you're telling us that 70% of calorie expenditure goes on regulating body temperature?

Sounds about right to me. someone that does zero exercise still needs thousands of calories everyday just to survive and that's in the case where they are in normal indoor environments where there aren't extreme temperature gradients to cope with. Compare that to the calorie intake of someone that exercises regularly and there isn't a huge difference.

Think about it, you've got a mass that's, I don't know, 70-100kg for a male that need to be kept 10-20 degrees above the ambient air temperature at all times. Do you really think that this takes a small amount of energy to do that?

Except of course when exercising hard heating yourself up is not the problem, indeed keeping cool is the problem - heat being a waste product of the work done producing the power.

Also, almost no sedentary person requires thousands of calories either, and 1000calories an hour could quite easily be burnt when exercising.

amaferanga

The trouble with stating that 70% of calorie expenditure goes on temperature regulation is that logically there should therefore be an ambient temperature that matches body temperature such that calorie expenditure to maintain body temperature would be close to zero. But there is no such temperature....

P_Tucker

Chiggy wrote:

P_Tucker wrote:

Chiggy wrote:

The ONLY way you can observe and record "Intensity" of human activity is to firstly measure the O2 and CO2 content of the ambient air, and secondly, measure the O2 and CO2 content of the poor chap's exhaled breath.

Try doing that on a road ride without a truck full of gas analysers..

So what's a powermeter then?

A powermeter is a dynamometer. It measures the power generated by the engine either at the crank, at the hub or at the roller.
In an engine test cell, the dynamometer is measuring the power generated by the engine. The engine will NEVER get to its full potential if you continuously swill freezing cold water through the cylinder head and not allow it to warm up to normal operating temperature.

On a Turbo trainer or ergometer, the rider will NEVER get to his/her full potential if he/she has freezing cold air blasing on his/her legs and ribcage throughout the test.

On an indoor Turbo, the room's ambient air and therefore the rider's skin temperature can be controlled to be the same at every test. On the road, it can't.

The purpose of a turbo trainer is to quantify any improvement in performance. This is done realistically with two O2 and CO2 analysers. These directly measure the rider's VO2 uptake and operates by the 'Carbon balance' theory of combustion efficiency.
If the cyclist uses the same equipment with every test, the turbo's powercurve is known, and the bike remains close to constant, AND SO DO THE ATMOSPHERIC CONDITIONS, so a faster speed with less VO2 indicates a more efficient engine. A powermeter merely confirms the fact.

In an engine test cell, intake air, exhaust gas AND fuel flow are measured as well as power output. On a cyclist on a turbo, it is difficult to measure fuel flow, so O2 and CO2 are used to calculate fuel usage for the power output.

Without knowing the balance of CO2 and O2, the research engineer can but guess the intensity of the rider's session.

Does that explain it better?

No, I'm going to need more detail.

Also, if you think body temperature can't be regulated on the road, then you've never tried Assos clothing.

kayakerchris

treble post

kayakerchris

About 70% of a human's total energy expenditure is due to the basal life processes within the organs of the body (see table). About 20% of one's energy expenditure comes from physical activity and another 10% from thermogenesis, or digestion of food (postprandial thermogenesis)

The comments on thermogenesis or thermoregulation are not quite accurate as the 70% is to do with all the activities of body maintenance and then another 10% comes from the energy released from food digestion.

Obviously for us cyclists pushing the turbo round for an hour will change the percentages, so that our total energy expenditure on physical activity is probably about 22%. This small change is why exercising on its own is a bad way to lose weight. The main benefits of exercise is a change in BMR as a result of increased lean muscle mass (high metabolic demand) and a decrease in fat (low metabolic demand). Some energy expenditure of course will also come from repairing the damage done by exercise to the body!!

The energy expended on thermoregulation increases as the temperature decreases or increases (shivering vs sweating) and there is a temperature at which the metabolic demand is least. I forget the exact temperature but go into any burns unit and you will find out pretty quickly!

UpTheWall

Thanks for the info chaps; fascinating stuff..

And chiggy - well done for rising above the rudeness of some of the other guys.

flanners1

Having done nearly 3 weeks on the rollers and no road ride. I have been climbing the walls, so ventured out this evening for a brisk 20 odd miler. Having been paranoid that my fitness was going I felt good on the bike, my pedalling was fluid and fast, a couple of the hills were hard but all in all the rollers have kept the base fitness going, I am happy

Chiggy

To bring us all back down to Earth.

Nice afternoon yesterday so I went out and took a little pootle round the hills nearby.

There's a 12% about 15 miles away, so I got a move on to warm up before takling the hill.

I went up the 12% at 7.5 mph, turning the cranks at 50 rpm on a 32 x 17 ( 50" ). The bike is 23 lb and CTC's PowerCalc.xls reckons I was pulling 420 Watts. The climb lasted 2 1/2 minutes so according to the 'Cycling Science' chart from Dave Wilson's book, I'm better than a 'Healthy man'.

I was dancing about a bit at 50 rpm, but it felt good. I wouldn't do that on the turbo!!

I was all dressed up for the winter and had a 3 ish mph sidewind from the west. More accuracy than this is futile. I'm chuffed as it is...

Tom Butcher

P_Tucker wrote:

x hours at y intensity on the road = x hours at y intensity on the turbo. The end.

+ 1

Tom Butcher

Chiggy wrote:

The purpose of a turbo trainer is to quantify any improvement in performance.

Sorry for coming to this late - posted the +1 comment when trawling through to page 3 and at last someone mentioned that there is nothing magical in turbo training that makes it worth more than road cycling.

Just to pick up on the quote above though - people can have different reasons for owning a turbo trainer but I'd guess that mostly it's about allowing them to train indoors rather than providing the ability to hold conditions constant so they can get some kind of gas analysis done on what they are breathing in and breathing out.

In reality of course yes many of us find it easier to do a hard interval session on a turbo than on a road on our own. On the other hand plenty find that a chain gang can bring out even greater levels of effort - or another way would be to stick a number on your back and race.

Chiggy

Doh!

What we are saying is IF you train at close on VO2 max, to allow oxygenated blood flow to the working muscles for TRAINING them to be stronger and more durable, it is beneficial to reduce temperature effects to a minimum, so less blood is pumped to the skin to keep warm or cool.

Disagree with me that VO2 uptake is the measure of intensity? If you can only uptake x VO2, part of it will be used for propulsion and part of it will be used to keep you alive.
Don't let the 'keeping you alive' part thieve off the 'propulsion' part.

PS When you work at such a high intensity that the 'keeping you alive' part is diverted to 'propulsion, you get "numb nuts", loss of feeling in the extremities and a dizzy head.

If you are old like me and your baby making days were a long time ago, "numb nuts" happens first.

Butterd2

Interesting debate there - thanks all.

For me turbo and road miles are 2 different things. I cannot imagine doing base endurance rides on the Turbo the boredom would too much to overcome, I can only do this on the roads.

However last night on the Turbo I did "The Hunted" and for the final 50sec sprint at 9/10 effort I had my head on the stem with my eyes shut, not something I think I should be doing on the road.

Bottom line the turbo allows me to do shorter but higher intensity workouts without worrying about crashing or bonking and not being able to get home. (I can also look after the kids at the same time, provided they keep their hands out of the spokes!)

Chiggy

One of cycling's golden rules is "Never close both eyes at the same time."

Therefore, even on the dyno, never do it. Make as if you're riding for real.

Tom Butcher

Chiggy wrote:

Doh!

What we are saying is IF you train at close on VO2 max, to allow oxygenated blood flow to the working muscles for TRAINING them to be stronger and more durable, it is beneficial to reduce temperature effects to a minimum, so less blood is pumped to the skin to keep warm or cool.

Disagree with me that VO2 uptake is the measure of intensity? If you can only uptake x VO2, part of it will be used for propulsion and part of it will be used to keep you alive.
Don't let the 'keeping you alive' part thieve off the 'propulsion' part.

PS When you work at such a high intensity that the 'keeping you alive' part is diverted to 'propulsion, you get "numb nuts", loss of feeling in the extremities and a dizzy head.

If you are old like me and your baby making days were a long time ago, "numb nuts" happens first.

Chiggy what I am disagreeing with you about is your statement that the purpose of a turbo trainer is to allow for a super accurate measurement of what your oxygen intake is.

Further I think so long as people rely on common sense to keep a comfortable temperature - using clothing, fans etc as appropriate - it's very unlikely that there is a significant difference in the training benefit derived from working at a given wattage for a given duration. However if you can point to any research showing that this is something we should all be taking into account I'm open to persuasion.

Further unless you are working at the limit your heart can pump blood round the body then having to divert some small amount of blood for cooling shouldn't necessarily reduce the amount of O2 the available to the relevant muscles should it - so whilst a gas analysis may show you are working harder would that be relevant to the training benefit for the muscles involved in cycling ?

Anyway off to work now.

UpTheWall

Interesting that some find it easier to go higher intensity on the turbo.

I find it more difficult to go hard on the trainer.

Also, to echo the reasoning for riding indoors. It's the temperature. My legs are just dead weights in the cold. I don't really get going until it hits around 20 degrees, (and find the zone closer to 30 degrees) so in the current weather I find myself riding like a granny on a tricycle.

I'm guessing this is to do with
a) muscles being tighter in the cold and hence less good circulation and efficieny
b) more energy required to warm the air in my lungs before I can process it, so harder to get the o2 to the muscles
c) more energy to stay warm.

Is that sensible?

Butterd2

Chiggy wrote:

One of cycling's golden rules is "Never close both eyes at the same time."

Excellent!! I'll try to remember that.

Chiggy

"your statement that the purpose of a turbo trainer is to allow for a super accurate measurement of what your oxygen intake is"

Did I say that?

What I implied was,, if you keep everything else consistant from turbo session to turbo session, you can see if you are improving or deteriorating.

The O2 and CO2 analysis scenario was to indicate what goes on behind close doors at Cycle team training camps. You won't find anything ( or very little ) on the internet because people who earn their wages trying to win races are not goiing to tell the world how they get better than the opposition.

What Chris Boardman did for the hour record surprised me!

There are scraps now and again in Cycling magazines showing riders on ergometers with mouthpeices to strange blue boxes, and a guy giving the rider a thumb prick test every five minutes.

In the absense of gas analysis equipment and a blood Lactate tester, the home rider can use a HR monitor and go on the web to find a calculator for VO2 uptake.

P_Tucker

Chiggy wrote:

What I implied was,, if you keep everything else consistant from turbo session to turbo session, you can see if you are improving or deteriorating.

Well now, that depends on the turbo and whether you calibrate it or not. I was surprised to find, when I started using a PT on the turbo, that for the same effort (as measured by the powermeter) the speed changed by 3kmh during the course of a 20 minute interval. One suspects that, longer term, as a turbo starts to wear the resistance will change.

Possibly even more relevant is that (for my fluid trainer at least) temperature affects the speed - turbo in my garage at about 5-10 degrees vs my ktichen at probably 20+ gives a difference of about 2kmh for the same power. If you turbo in a garage, you might find that from winter through spring to summer you are apparently improving, whereas in reality its just because it's getting warmer.

So, to sum up, turbos aren't that great as a measure of output. And don't get me started on the ones that supposedly measure power like the Tacx ones.

flanners1

Crikey shall we just ride our bikes?! This is getting scary................ :shock:

Pokerface

P_Tucker wrote:

x hours at y intensity on the road = x hours at y intensity on the turbo. The end.

Of course this is correct - in the strictest interpretation.

But it's significantly harder (perception-wise?) to maintain the same intensity on the road.

Please explain to me why I can easily do 3 hours on the road at an average of say 200w, but cannot do 2 hours on the turbo at the same wattage?

Could it be because the power outputs vary on the road (going up hills, resting going downhill, etc) while on the turbo the effort needs to be constant? I agree that the amount of work done and the total amount of power produced, etc is the same - but please explain why it is so much harder to do it on the turbo.