The Powermeter Thread

[CoachFergie]

Nice wee summary of racing and training with a Power Meter.

http://www.youtube.com/watch?v=cSqEAX9mRq8

 

[CoachFergie]

Huh? What comments about power? I didn't find anything except this:

"Cancellara putting out some massive watts"

from the live coverage. Did I miss something?

I'm sure he was putting out some massive watts. They just weren't being measured.

 

[durianrider]

bottom line if you want to pace properly then use a power meter. the reason I can smash so many riders on the climbs is I know my wattage I can hold from 1 minute to 30mins up a climb.

All those KOM's I have on strava is largely due to me using a power meter. That way I can use my super high watts per kg to KOM all day without blowing up too early.

Premature lactic acid build up is the main reason riders explode up a climb and lose overall time relative to what they could have done if they pace with a power meter.

 

[CoachFergie]

bottom line if you want to pace properly then use a power meter. the reason I can smash so many riders on the climbs is I know my wattage I can hold from 1 minute to 30mins up a climb.

All those KOM's I have on strava is largely due to me using a power meter. That way I can use my super high watts per kg to KOM all day without blowing up too early.

Premature lactic acid build up is the main reason riders explode up a climb and lose overall time relative to what they could have done if they pace with a power meter.

Was talking with Gordon MacCauley after his win in the NZ Club Champs last week. 6 lap race. First two times on the climb at 380 watts, 2nd two at 400 watts and final two laps at 420 watts. Tempo on the climbs and driving the break on the flat.

People accuse Sky of being predictable using power to measure their efforts (both meanings) but it is highly effective.

 

[durianrider]

bingo.

for the next 5 years I will dominate the local climbs until more riders get on board power meters and start calling my bluff lol!

 

[Alex Simmons/RST]

bottom line if you want to pace properly then use a power meter. the reason I can smash so many riders on the climbs is I know my wattage I can hold from 1 minute to 30mins up a climb.

All those KOM's I have on strava is largely due to me using a power meter. That way I can use my super high watts per kg to KOM all day without blowing up too early.

Premature lactic acid build up is the main reason riders explode up a climb and lose overall time relative to what they could have done if they pace with a power meter.

While I don't know the precise details of the climb (only been up it once myself about 12 years ago), and don't propose to analyse your data in any detail, your comment when analysing your pacing of the climb, about spiking of power on steep bits and recovering a bit on the lesser gradients might need some smoothing out to gain a better time may not be correct.

When faced with variable gradients, it makes sense to vary the power output accordingly, and within certain optimisation limitations, such as your overall capability for climb duration, as well as shorter duration mean maximal powers.

IOW - you get more speed return for your overall energy budget if you apply a higher power on the harder sections and less power on the easier sections.

If the climb is all steep, then steady state will typically be faster, but where there are flatter sections interspersed along the way, then the strategy for fastest time requires a variable power output.

 

[Dear Wiggo]

Was talking with Gordon MacCauley after his win in the NZ Club Champs last week. 6 lap race. First two times on the climb at 380 watts, 2nd two at 400 watts and final two laps at 420 watts. Tempo on the climbs and driving the break on the flat.

People accuse Sky of being predictable using power to measure their efforts (both meanings) but it is highly effective.

6W/kg is tempo eh?

 

[JayKosta]

...
Premature lactic acid build up is the main reason riders explode up a climb and lose overall time relative to what they could have done if they pace with a power meter.

-
Do you NOW really 'need' the power meter to guide your level of exertion, or can you determine the level by how you feel - RPE (relative perceived exertion), breathrate, heart pounding, etc.?

Jay Kosta
Endwell NY USA

 

[CoachFergie]

6W/kg is tempo eh?

Depends on the duration. The climb was 800m long.

 

[CoachFergie]

-
Do you NOW really 'need' the power meter to guide your level of exertion, or can you determine the level by how you feel - RPE (relative perceived exertion), breathrate, heart pounding, etc.?

When analysing race files the most common thing I see if poor pacing. Expending too much energy early in the race and hitting the climbs too hard. Seeing you can't record RPE every second like power you would have no way to assess how well a rider was pacing by feel.

 

[Dear Wiggo]

-
Do you NOW really 'need' the power meter to guide your level of exertion, or can you determine the level by how you feel - RPE (relative perceived exertion), breathrate, heart pounding, etc.?

Jay Kosta
Endwell NY USA

Yes, you can. Especially on climbs you train on repeatedly.

 

[Krebs cycle]

So while they have interesting technology, why does these unfounded/unproven notions persist as some kind of perceived benefit?

Provide the measurement tool, prove it works as claimed, but please let the scientific process assess whether or not such such notions have any valid grounding for performance improvement (because so far the science would suggest it doesn't).

It's not really the job of the manufacturer though to conduct research about whether or not cycling efficiency can be altered using real-time biofeedback of both positive and negative work performed during cycling, which is what the Axiscranks ergometer does. Can any other ergometer do this at present? Has a study been conducted which uses such methodology and then examines pedalling efficiency and performance?

You are correct, the scientific process needs to do the work, however at present I don't believe there is a single study using this ergometer because as far as I know, there are only about 4 or 5 in existence at present.... one of which just happens to be in the ex phys lab just across the hall from my office

So I can assure you, the science WILL be done! In the meantime, I believe there is enough evidence around to suggest that muscle recruitment patterns can affect performance....

http://www.ncbi.nlm.nih.gov/pubmed/22089483

http://www.ncbi.nlm.nih.gov/pubmed/20086134

http://www.ncbi.nlm.nih.gov/pubmed/17258470

Now back to power meters.

 

[CoachFergie]

It's not really the job of the manufacturer though to conduct research about whether or not cycling efficiency can be altered using real-time biofeedback of both positive and negative work performed during cycling, which is what the Axiscranks ergometer does. Can any other ergometer do this at present? Has a study been conducted which uses such methodology and then examines pedalling efficiency and performance?

Has this been validated that it does indeed measure what they claim?

 

[Alex Simmons/RST]

Now back to power meters.

I can't even recall what that was about.

 

[Krebs cycle]

I can't even recall what that was about.

Is wasted force at "top dead centre" detrimental to performance?

We just got one of the AxisCranks ergos in our lab and I'm interested to know if using real time biofeedback of pedalling force could be used to improve muscle coordination. If muscle coordination can be improved and negative work can be reduced, there is a physiological rationale for improved efficiency.

Will this work? Don't know, need to conduct a study to find out. Hopefully we're going to do it within the next 12 months.

Has this been validated that it does indeed measure what they claim?

The page of interest on the website is here...

http://axiscranks.com/market-applications/bicycle-cranks/

What the manufacturer claims is that it measures both compression/tension and bending forces on each crank arm independently (ie: both cranks each have an array of strain gauges), and therefore both gross power and tangential power are being measured. When you ride it, you can select various stuff to watch in real time such as the graphs shown on the webpage, or simply just "positive" and "negative" power which I assume refers to the tangential and (gross -tangential) power respectively.

One of my colleagues has discussed the dynamic calibration procedure with the manufacturer (who is well known and trusted within Australian sport engineering circles) and it seems pretty comprehensive. Put it this way, the best way to "validate" the claim that it measures both gross power and tangential power is to build a custom designed dynamic calibration rig. The manufacturer has done that already so essentially it comes "factory calibrated".

 

[CoachFergie]

Thanks. I laid my hands on a pair at Massey a couple of years ago. I look forward to seeing your research.

 

[FrankDay]

Is wasted force at "top dead centre" detrimental to performance?

We just got one of the AxisCranks ergos in our lab and I'm interested to know if using real time biofeedback of pedalling force could be used to improve muscle coordination. If muscle coordination can be improved and negative work can be reduced, there is a physiological rationale for improved efficiency.

I would like to point out one area that I think has been a source of error in interpretation. Other studies have tried to correlate "force effectiveness" with efficiency and found no correlation. The problem is pedal forces can come from both gravity (and inertia) and muscle contraction. Of course, only the muscle contraction component is important to mechanical efficiency. The muscle contraction force might be in a very "effective" direction but the gravity component might make the total look very ineffective. By the same token a very ineffective muscle contraction force might be made to look more "totally" effective when we add in the gravity component, which would actually make the rider less efficient. Interpreting pedal forces and overall efficiency becomes extremely complicated and difficult as a result. If your study could be done in space, a zero gravity environment, this would be much less an issue. Good luck.

Will this work? Don't know, need to conduct a study to find out. Hopefully we're going to do it within the next 12 months.

The page of interest on the website is here...

http://axiscranks.com/market-applications/bicycle-cranks/

What the manufacturer claims is that it measures both compression/tension and bending forces on each crank arm independently (ie: both cranks each have an array of strain gauges), and therefore both gross power and tangential power are being measured. When you ride it, you can select various stuff to watch in real time such as the graphs shown on the webpage, or simply just "positive" and "negative" power which I assume refers to the tangential and (gross -tangential) power respectively.

One of my colleagues has discussed the dynamic calibration procedure with the manufacturer (who is well known and trusted within Australian sport engineering circles) and it seems pretty comprehensive. Put it this way, the best way to "validate" the claim that it measures both gross power and tangential power is to build a custom designed dynamic calibration rig. The manufacturer has done that already so essentially it comes "factory calibrated".

It seems to me that these cranks could also be "validated" by comparing their output to force plate pedals which have been around for awhile (although your institution may not have these). Anyhow, good luck.

 

[JayKosta]

As Frank mentioned earlier, there will be non-muscular forces due to gravity, and circular inertia/momentum. Those should be incorporated into the data analysis - possibly with the assistance of a computational physicist.

Jay Kosta
Endwell NY USA

 

[CoachFergie]

An updated review on the Stages power meter.

http://www.dcrainmaker.com/2013/06/stages-review-update.html

 

[CoachFergie]

Some good information for those interested in racing and training with a power meter.

http://www.slowtwitch.com/Tech/Power_Meter_101_3643.html

http://www.slowtwitch.com/Tech/Power_Meter_201_3672.html

http://www.slowtwitch.com/Tech/Power_Meter_301_3696.html

 

[FrankDay]

We just got one of the AxisCranks ergos in our lab and I'm interested to know if using real time biofeedback of pedalling force could be used to improve muscle coordination. If muscle coordination can be improved and negative work can be reduced, there is a physiological rationale for improved efficiency.

This was posted back in April. I wonder if Krebs has some initial impressions/thoughts?

 

[CoachFergie]

Should also mention that Golden Cheetah 3.0 is now available. Still a little clunky to move around compared to WKO 3.0. WKO+ 4.0 is in the works and Dr Coggan has been teasing us with some of new analysis tools it may offer. I'm hoping that TrainingPeaks online will eventually shift from Flash to HTML5.

http://goldencheetah.org/

I was using it this afternoon. WKO+ allows me to set up charts looking at what I see but I need GC to download two files into excel to publish that chart I used a few pages ago.

Instead of TSS, Golden Cheetah uses Bike Score. Dr Phil Skiba has done a nice write up about Bike Score...

http://www.physfarm.com/bikescore.pdf

 

[Parrot23]

Useful info., CoachFergie. Keep it coming.... Thanks.

 

[acoggan]

We just got one of the AxisCranks ergos in our lab and I'm interested to know if using real time biofeedback of pedalling force could be used to improve muscle coordination. If muscle coordination can be improved and negative work can be reduced, there is a physiological rationale for improved efficiency.

Will this work? Don't know

Ask Peter Cavagnagh/the 1984 US Olympic Team Pursuit squad.

 

[CoachFergie]

An abstract from a study presented at European College of Sport Sciences in Barcelona...

RESULT OF AN INDIVIDUALIZED CYCLING TRAINING PROGRAM THROUGH POWER METERS
Authors: FERNÁNDEZ-MONTILLA, J.A., LÓPEZ-GRUESO, R., SARABIA, J.M., ARACIL, A., GUILLÉN, S., PASTOR, D., MOYA, M. - [Contact]
Institution: GIAFIS, SPORTS RESEARCH CENTRE, UNIVERSIDAD MIGUEL HERNÁNDEZ DE ELCHE (SPAIN)
Department: PSICOLOGIA DE SALUD
Country: SPAIN
Abstract text
Introduction The theoretical framework for quantifying the training proposed by Dr. Coggan (Allen and Coggan, 2010) parts of the biparametric models theory applied to cycling and bike segment in triathlon. The aim of the study was to evaluate the influence that an individualized training program at different percentage of functional threshold power (FTP) Methods Fourteen triathletes (aged 38.12 ± 6.37 years) were divided into two groups (Control -C- and Experimental, -E-) and developed six weeks of planned workouts, with a pre and post-test in both cycle ergometer (Monark ergomedic 839) and field tests (Powertap, CycleOps, Madison, USA). The program focuses on the critical pedaling power with normalized power (NP) and decreasing by 30% the intensity factor (IF), developing a working method based on the and training stress score (TSS) on the basis of an individualized FTP for each subject (E) versus usual training group (C). The variables evaluated were: maximal oxygen uptake (VO2max), time to exhaustion (tExh), power generated at the second ventilatory threshold (wVT2), lactate threshold (LT) on a cycle ergometer test, and volume in kilometers (Vkm), absolute and relative power generated in the FTP field test (wFTP and w/kgFTP). Results The average values show no significant differences between both groups in the different tests and variables assessed at the pre y post- tests. However, a beneficial trend (in favor of experimental group) is clearly marked in all of them: wFTP (C: 256.6±22.4 to 260.0±16.9w vs E: 236.0±19.3 to 248.0±25.0w), w/kgFTP (C: 3.34±0.32 to 3.33±0.27w/kg vs E: 3.53±0.21 to 3.67±0.20w/kg), tExh (C: 14.71±1.08 to 14.89±1.43min vs E: 12.29±1.89 to 13.50±1.86min), wVT2 (C: 267.9±12.2 to 271.4±17.3w vs E: 239.3±19.3 to 260.7±24.4w), wLT (C: 200.0±0.0 to 204.2±19.0w vs E: 158.3±34.0 to 170.8±43.0w), w/kgLT (C: 2.60±0.08 to 2.60±0.27w/kg vs E: 2.42±0.53 to 2.63±0.73w/kg) and lactate production at LT kgLT (C: 2.23±0.37 to 1.95±0.61mM vs E: 2.12±0.60 to 2.32±0.73mM). The decline in VO2max had a negative trend less marked in the experimental group also (C: 55.1±2.1 to 54.0±2.2 ml/kg/min vs E: 55.4±3.5 to 55.0±3.9ml/kg/min, p=0.088). Discussion For group C which was training a larger volume at different IF and not individualized %UPF (but the same NP) is not guaranteed performance improvement. This group even manifests a negative trend, while group E, with relatively lower but personalized volumes, shows a slight improving trend, although not significant. References Allen H, Coggan A. (2010). Training and racing with a power meter. Velopress, Colorado.

Topic: TRAINING AND TESTING
Keyword I: FTP
Keyword II: BIPARAMETRIC MODELS THEORY
Keyword III: TRIATHLON