Power Data Estimates for the climbing stages

[halamala]

On stage 13 of the 2008 Vuelta a Espana, Contador had around 6.3 W/kg +/- 0.1 W/kg on the massive Angliru. I watched it with great interest.

Tour 2007, Stage 14, Plateau de Beille
Contador: VAM 1680 m/h, 6.00 w/kg

Tour 2007, Stage 15, Col de Peyresourde
Contador: VAM 1619 m/h, 5.86 w/kg

Tour 2007, Stage 16, Col d'Aubisque
Contador: VAM 1637 m/h, 6.01 w/kg

Giro 2008, Stage 15, Passo Fedaia
Contador: VAM 1572 m/h, 5,48 w/kg

Vuelta 2008, Stage 13, Angliru (last 6.5 km, Grade 13.12 %)
Contador: VAM 1847 m/h, ? w/kg because the last 6.5 km steeper than 11 %

Vuelta 2008, Stage 14, Fuentes de Ivierno
Contador: VAM 1555 m/h, 5.82 w/kg

Vuelta 2008, Stage 20, Puerto de Navacerrada (ITT)
Contador: VAM 1441 m/h, 5.38 w/kg

Tour 2009, Stage 7, Arcalis
Contador: VAM 1676 m/h, 6.19 w/kg

Tour 2009, Stage 17, Col de Romme
Contador: VAM 1807 m/h, 6.17 w/kg

Tour 2009, Stage 17, Col de la Colombiere
Contador: VAM 1687 m/h, 5.91 w/kg

Tour 2009, Stage 20, Mont Ventoux
Contador: VAM 1642 m/h, 5.97 w/kg

 

[Cozy Beehive]

That's standard "cardiac drift": stroke volume, I think, declines with dehydration/heat. Heart compensates for lower stroke volume by beating faster. Doesn't mean you are working harder. One reason why Lemond wished he had an SRM in his day.

Right, that too. So I'm talking about a HR drift superimposed upon a slow component of VO2 drift with prolonged exercise at moderate to submaximal levels. Cycling at constant power output or "perceived effort" or whatever it maybe doesn't mean your HR is staying mum where you want it to be. There's lots of variables that can affect HR, which is what I meant to Dr. Coggan.

 

[Cozy Beehive]

Tour 2007, Stage 14, Plateau de Beille
Contador: VAM 1680 m/h, 6.00 w/kg

Tour 2007, Stage 15, Col de Peyresourde
Contador: VAM 1619 m/h, 5.86 w/kg

Tour 2007, Stage 16, Col d'Aubisque
Contador: VAM 1637 m/h, 6.01 w/kg

Giro 2008, Stage 15, Passo Fedaia
Contador: VAM 1572 m/h, 5,48 w/kg

Vuelta 2008, Stage 13, Angliru (last 6.5 km, Grade 13.12 %)
Contador: VAM 1847 m/h, ? w/kg because the last 6.5 km steeper than 11 %

Vuelta 2008, Stage 14, Fuentes de Ivierno
Contador: VAM 1555 m/h, 5.82 w/kg

Vuelta 2008, Stage 20, Puerto de Navacerrada (ITT)
Contador: VAM 1441 m/h, 5.38 w/kg

Tour 2009, Stage 7, Arcalis
Contador: VAM 1676 m/h, 6.19 w/kg

Tour 2009, Stage 17, Col de Romme
Contador: VAM 1807 m/h, 6.17 w/kg

Tour 2009, Stage 17, Col de la Colombiere
Contador: VAM 1687 m/h, 5.91 w/kg

Tour 2009, Stage 20, Mont Ventoux
Contador: VAM 1642 m/h, 5.97 w/kg

Thanks a lot. How did you calculate all this? Or was this from a data base?

Here, I must say very importantly that the 6.3 W/kg was calculated by me with a limited Eurosport footage, from the 4K to go mark. He took 15.4 minutes to complete it, going by the footage. For the entire length of climb (12.5 K or so), his average W/kg would be a bit lower, which is why I gave the error bars. So I say 6.1 to 6.2 W/kg for the entire climb, not more. Still an eye popping effort. I never get bored watching it.

 

[acoggan]

I think you mean the Daupine? They tend to do the Tour de Suisse in, well, Switzerland.

Yes, I meant the Dauphine (remember what I said about not paying much attention to men's pro road racing?).

do you have any insight into the rigor those guys apply to such things?

Only enough to say that 1) it varies with the individual, and 2) there doesn't seem to be any relationship whatsoever between someone's talent as a cyclist and their attention to such details.

To your greater point about power needing to drop over a 3 week stage race, I'll say that like you on Lance's alleged doping, I'm agnostic. As you've pointed out, I've seen personal best numbers during periods of high fatigue. However, a drop in HCT has been documented (Basso's blood values, anecdotal comments from team physicians, comments from LeMond ((I honestly don't know if this is supposition on his part or actual test results)), the published study on the MTB stage race guys). Of course, your link seems to demonstrate that it's not absolutely necessary.

Likewise, I guess it's possible that an increase in efficiency could overcome a drop in HCT.

Don't confuse changes in hematocrit with changes in total red cell mass (with which performance is much more closely correlated).

 

[acoggan]

When I used to be into heart rate monitors, I discovered the simple principle of the slow component of VO2. On several flat 70-100 mile rides where my goal for the day was to maintain constant speed (or effort) just to enjoy the day, I was surprised to find that heart rates kept climbing up steadily until towards the end of the rides, my lungs were heavy and I was beyond 70% of my max HR. I wondered if I had some kind of heart problem. Why could I not get my HR to be constant in spite of trying to bike at submaximal level. There is a definite relationship between exercise intensity indicators of VO2 and HR. 55% VO2 max corresponds to about 70% max heart rate. This is why I wrote that maintaining a constant power output or speed does not necessarily mean your HR is steady. It will climb as your body needs more oxygen to process for sustaining the same workload, in other words...body becomes less efficient.

Due to cardiac drift, you can't use changes in heart rate during prolonged exercise as an indicator of changes in metabolic rate.

How do you know efficiency goes up throughout a 3 WK grand Tour?

I don't know that it does. That is, however, what you would predict to occur (and what has been found by, e.g., Brent Ruby, to occur upon a sudden and sustained increase in training load).

 

[acoggan]

I'm talking about a HR drift superimposed upon a slow component of VO2 drift with prolonged exercise at moderate to submaximal levels.

There is little or no increase in metabolic rate during prolonged cycling at such intensities. The "slow component" is only evident during exercise at higher intensities.

 

[Cozy Beehive]

There is little or no increase in metabolic rate during prolonged cycling at such intensities. The "slow component" is only evident during exercise at higher intensities.

Right. For higher intensities, as seen in the Tour, it definitely comes into play. I always want to see HR info along with power output. Just power output alone is as good as no information.

 

[Lajeretta4Ever]

It looks like the good doctor has a different take on the Power numbers in this year's tour. He claims AC and AS did the Tourmalet at 6.4

53x12

 

[Cozy Beehive]

It looks like the good doctor has a different take on the Power numbers in this year's tour. He claims AC and AS did the Tourmalet at 6.4

53x12

Its for last 9 km. I came up with 6.03 W/kg for the last 8. Overall, for the full climb, 5.8-6.0 W/kg, not more not less.

Interesting he says :

From this perspective, it's been a rather boring and disappointing TdF, dominated by Contador.

He apparently had no problem with LA doping up (according to many people) and dominating for 7 years.

 

[Le breton]

Approaching the final figures for Tourmalet 2010

...........
Overall, for the full climb, 5.8-6.0 W/kg, not more not less.

Note : I answer here but I could have posted this anywhere else, it's not Cozy in particular that I address.

Copied from my TOURMALET WEST SIDE post
Today the stage ends at the Tourmalet.
Bottom of the climb in Luz St-Sauveur at 711m asl.
top, 18.7 km later and 1404 m. higher.

Assume no draft, a 70 kg cyclist, with 8kg equipment.
Take CdA = 0.4 m^2

assume average temperature 25°C. -> av. air density 1.03 g/cm^3.

Neglect the fact that the 1st km is not so steep . 4.5% or so.

Run various climbing speeds on analyticcycling.com

49 min : air resist = 53 watts , grav+rr = 383 W Total 436 watts
ie 6.23 watts/kg
add 2.5% for transmission loss = 6.38 W/kg
add 3% to compare with sea-level effort => 6.57 W/kg.

52 min : air res. 44 W, grav+r.r. = 361 watts total 405 watts
ie
5.78 W/kg
add 2.5% transmission -> 5.9 W/kg
add 3% to compare to sea-level => 6.07 W/kg.-----

Drafting behind one racer reduces air resistance by about 25%, a saving of 11 watts for 52 min, ie 0.16 W/kg

At 49 min, the saving is 13 watts, ie 0.19W/kg.

End of copy

Therefore, a 70 kg racer (*+8kg) would require
1314 SRM kJ to climb Tourmalet in 49 min
1295 SRM kJ to do it in 52 min.
Interpolating we get 1304 SRM kJ for 50:37

If we assume drafting for half the duration the reduction in kJ required will be 18 kJ, which gives 1286 kJ. => 423 SRM watts or 6.05 W/kg for Schlek (without altitude effect correction)

Note that this still depends on the altitude difference covered being really 1404 meters over 50:37.

COMPARISON WITH HORNER’S SRM

Now, what do we get for a 64 kg (+8kg) racer drafting for the whole 52:22 duration of the climb?
Energy expenditure for a 70 kg (+8kg) racer climbing in 52:22 no drafting => about 1295 kJ reduced to 1260 kJ if drafting the whole time.

For a 64 kg(+8 kg) racer drafting the whole time this becomes 1163 kJ
For a 65 kg(+8 kg) racer drafting the whole time this becomes 1179 kJ

Insignificant adjustements could be made for the temperature and , slightly more significant corrections should be made for the somewhat flattish first 2 km and for the CdA not scaling exactly as the weight ( but the latter would really be a nonsensical adjustment).

This 1163 kJ is to be compared with 1132 kJ registered by Horner’s SRM, an overestimation of 2.7%. But then, of course, I only know Horner’s weight from the SRM comment that 377 watts corresponds to 5.9W/kg and we don’t know about the calibration of his SRM.

Is a difference of 2.7% acceptable? Not completely because I would have expected to end up with an underestimation as some factors were not taken into account: significant speed variations in the first minutes of the climb, wet road which increased slightly the weight of the equipment (clothe, shoes). Note that with a SRM there is no need to correct for transmission efficiency.

But it’s too early for final conclusions as there are still uncertainties on the starting and finishing altitudes for that 18.6km climb. We’ll come back to this when Portoleau publishes his observations on cyclismag.

NOTE . Constructive criticism more than welcome

 

[acoggan]

Right. For higher intensities, as seen in the Tour, it definitely comes into play.

The slow component of VO2 is only really significant during exercise above critical power/maximal lactate steady state/functional threshold power. IOW, you wouldn't expect to see much, if any, VO2 drift during extended climbs such as being discussed here.

I always want to see HR info along with power output. Just power output alone is as good as no information.

I don't think heart rate data really adds any useful information in the present context, as it is too influenced by multiple extraneous variables and only indirectly reflects the strain imposed on one physiological system.

 

[acoggan]

Note that with a SRM there is no need to correct for transmission efficiency.

??

(BTW, I think 0.4 m^2 is a large overestimate of someone like Horner's or Contador's CdA...I'm 1.83 m and 67-68 kg, and my CdA on a Merckx-style road bike is only 0.3 m^2. Of course, the amount of power required to overcome wind resistance while climbing a mountain isn't huge, but every little bit helps, right?)

 

[Le breton]

??

(BTW, I think 0.4 m^2 is a large overestimate of someone like Horner's or Contador's CdA...I'm 1.83 m and 67-68 kg, and my CdA on a Merckx-style road bike is only 0.3 m^2. Of course, the amount of power required to overcome wind resistance while climbing a mountain isn't huge, but every little bit helps, right?)

Remember that this is a climb, and with the exception of Ullrich in the AdH 2004 TT, I don't remember many racers adopting an aerodynamic position while climbing.
Also, I thought it was meaningless to try to reduce the CdA for a 64 kg racer as compared to a 70 kg racer in view of uncertainties on the effects of drafting and of wind ( was it favorable or significant? don't know at this point).

0.3m^2! man you are aerodynamic! I am less 1.70m (shrinking with age, don't want to know how much) and around 60-61 kg (probably less right now), very flexible, bend down low, less spokes than Merckx, yet I only get down to about 0.32m^2! (much more uphill of course). Maybe I should shave my legs

 

[Cozy Beehive]

The slow component of VO2 is only really significant during exercise above critical power/maximal lactate steady state/functional threshold power. IOW, you wouldn't expect to see much, if any, VO2 drift during extended climbs such as being discussed here.

Reiterated. High intensities.

I don't think heart rate data really adds any useful information in the present context, as it is too influenced by multiple extraneous variables and only indirectly reflects the strain imposed on one physiological system.

Reiterated. I want to see HR info. It is absolutely relevant along with power information, speed and grade.

 

[acoggan]

Reiterated. High intensities.

You seem to be missing the point: you won't see significant VO2 drift during a 40+ min effort (although heart rate can drift upwards quite a bit).

Reiterated. I want to see HR info. It is absolutely relevant along with power information, speed and grade.

Heart rate data are at best redundant and at worst misleading.

 

[acoggan]

0.3m^2! man you are aerodynamic!

Better than average, yes, but not hugely so.

I am less 1.70m (shrinking with age, don't want to know how much) and around 60-61 kg (probably less right now), very flexible, bend down low, less spokes than Merckx, yet I only get down to about 0.32m^2! (much more uphill of course). Maybe I should shave my legs

It sounds to me as if you are significantly overestimating your CdA - how did you quantify it?

 

[Cozy Beehive]

You seem to be missing the point: you won't see significant VO2 drift during a 40+ min effort (although heart rate can drift upwards quite a bit). Heart rate data are at best redundant and at worst misleading.

You make me laugh. Thanks for your opinions.

 

[ProfTournesol]

hey, interesting thread - keep it up, I'm learning a lot

 

[Le breton]

...........
you are significantly overestimating your CdA - how did you quantify it?

A long time ago by "dropping down" mountain passes. Ventoux, Malaucène side would be GREAT for this, but it's far.

About 5-10 years ago by trying to get consistent results tying up my Powertap watts data with calculated watts estimates on flat loops, particularly one 3.1 km loop around a lake, on windless days (over a range of speeds). I can't remember ever getting below 0.31 m^2.

Also tried a cement 350m track on the days of the LOOK Max1 with my road bike, but that was hopeless really , it drifted too much over just a 1 or 2000km, had to recalibrate all the time over a given mountain slope.

 

[Cozy Beehive]

A long time ago by "dropping down" mountain passes. Ventoux, Malaucène side would be GREAT for this, but it's far.

I remember writing this two years back. A Field Test for Calculating Aerodynamic Drag Area. Hope that can help you. 0.3m^2 for drag area is an ideal figure for very lean racers. Numbers I have seen working with some anthropometric data for Navy Seals is around 0.32 - 0.33m^2. The best methods to determine frontal area now seem to be CAD related measurements. Pro/E or Solidworks could do it.

 

[Mr.38%]

Don't confuse changes in hematocrit with changes in total red cell mass (with which performance is much more closely correlated).

I found this study really interesting. But aerobic fitness is not just about blood volume and red cell mass. Cortisol goes up, creatine kinase goes up, testosteron goes down. Once you start overreaching sleep gets worse, you lose your appetite and dang - you're spiraling down.

 

[Le breton]

AdH at Dauphiné 2010 (june 12)

His maximal power for 10 min
..........
(BTW, has anybody attempted to estimate Contador's power from the l'Alpe de Huez stage of the Tour de Suisse? I have a very good idea of what it was, so it's interesting to compare that value - produced at the end of a much shorter stage race - to the estimates in this thread for when he and Schlek went mano y mano after 3 wk of racing.)

Yes, F.P. at cyclismag wrote
Alberto Contador a bien débuté l'Alpe

Alberto Contador vainqueur de l'étape du Critérium du Dauphiné a escaladé l'Alpe d'Huez en 42min20s à une vitesse moyenne de 19.56 km/h. C'est 5min25s de plus que le record de Pantani de 1995.
Entre le pied du col et la Chapelle saint Férréol (à 6.5 km du sommet), Contador et Brajkovic ont développé une puissance moyenne de 420 watts (pour un coureur étalon de 78 kg) pendant un effort de 23min17s. A ce moment là, ils avaient un *** de 1min25s sur le temps de passage de Carlos Sastre en 2008.
Plus haut,le fort vent de face n'a pas permis d'estimer la puissance développée. Contador et Brajkovic ont ralenti leur rythme. En maintenant la même allure, ils auraient pu grimper l'Alpe d'Huez dans sa globalité en 40min20s environ.
Brajkovic et Contador ont réalisé une performance assez élevée sur la première partie de l'ascension.
-----------
The estimate of 420 watts is as usual for a 70 kg racer. i.e 6.0 watts/kg from the foot of the climb to a place 6.5 km from the finish line, ie roughly 7km into the climb.
Due to the wind, he did not try to estimate Contador-Brajkovic power over the whole climb. (I was at hairpin #1 and I can confirm that the wind was pretty annoying, pushing clouds downwards.)

 

[tobsie]

Any numbers on Contador and Michael Rasmussen from the col d'aubisque climb in 07?

 

[acoggan]

Yes, F.P. at cyclismag wrote
Alberto Contador a bien débuté l'Alpe

Alberto Contador vainqueur de l'étape du Critérium du Dauphiné a escaladé l'Alpe d'Huez en 42min20s à une vitesse moyenne de 19.56 km/h. C'est 5min25s de plus que le record de Pantani de 1995.
Entre le pied du col et la Chapelle saint Férréol (à 6.5 km du sommet), Contador et Brajkovic ont développé une puissance moyenne de 420 watts (pour un coureur étalon de 78 kg) pendant un effort de 23min17s. A ce moment là, ils avaient un *** de 1min25s sur le temps de passage de Carlos Sastre en 2008.
Plus haut,le fort vent de face n'a pas permis d'estimer la puissance développée. Contador et Brajkovic ont ralenti leur rythme. En maintenant la même allure, ils auraient pu grimper l'Alpe d'Huez dans sa globalité en 40min20s environ.
Brajkovic et Contador ont réalisé une performance assez élevée sur la première partie de l'ascension.
-----------
The estimate of 420 watts is as usual for a 70 kg racer. i.e 6.0 watts/kg from the foot of the climb to a place 6.5 km from the finish line, ie roughly 7km into the climb.
Due to the wind, he did not try to estimate Contador-Brajkovic power over the whole climb. (I was at hairpin #1 and I can confirm that the wind was pretty annoying, pushing clouds downwards.)

Thanks - so more evidence that such estimates are no better than +/- 5%.

 

[Le breton]

QUOTE=acoggan;311939]Thanks - so more evidence that such estimates are no better than +/- 5%.[/QUOTE]

Easy for you to say.
Do you have any supporting evidence that it is not better than +/- 5%? If so, show it. Or must we stay in the dark? Are you going to tell us that you have privileged information that you are not allowing yourself to divulge.

Besides, how are we going to know that the powermeter was well calibrated, etc.?
--
I just ran a quick analyticcycling calculation to get an idea of the maximum possible error on the estimate.
Air resistance with the parameters given = 8% of total for a lone racer.

If you know the exact altitude at the start and finish, there is no error on the calculation in normal circumstances for the gravity part ( near 90% of total energy expenditure).
One should make a slight correction for the altitude equivalence of 1/m.v^2 at the start and finish (about 4-5m equivalent for those guys).
The error on rr is negligible in absolute terms.

So the only real source of error is drafting estimate and CdA while climbing.
But the total air resistance represents only 8% for a lone climber, so that it seems impossible to overestimate the total power by more than about 2%.

However, I noted recently that FP applies a 2.5% increase on his calculated power to account for loss in transmission efficiency, maybe he is forgetting that unlike the Powertap the SRM measures power at the crank . I don't know how long he has been applying that (unwarranted in my mind) correction to his estimates.

Got to go
Cheers