The Powermeter Thread

[CoachFergie]

Reliability of Mean Power Recorded During Indoor and
Outdoor Self-Paced 40 km Cycling Time-Trials

M. F. Smith, R. C. R. Davison, J. Balmer, S R. Bird

Abstract
PURPOSE:
To determine the relationship between maximum workload (W(peak)), the workload at the onset of blood lactate accumulation (W(OBLA)), the lactate threshold (W(LTlog)) and the D(max) lactate threshold, and the average power output obtained during a 90-min (W(90-min)) and a 20-min (W(20-min)) time trial (TT) in a group of well-trained cyclists.
METHODS:
Nine male cyclists (.VO(2max) 62.7 +/- 0.8 mL.kg(-1).min(-1)) who were competing regularly in triathlon or cycle TT were recruited for the study. Each cyclist performed four tests on an SRM isokinetic cycle ergometer over a 2-wk period. The tests comprised 1) a continuous incremental ramp test for determination of maximal oxygen uptake (.VO(2max) (L.min(-1) and mL.kg(-1).min(-1)); 2) a continuous incremental lactate test to measure W(peak), W(OBLA), W(LTlog), and the D(max) lactate threshold; and 3) a 20-min TT and 4) a 90-min TT, both to determine the average power output (in watts).
RESULTS:
The average power output during the 90-min TT (W(90-min)) was significantly (P < 0.01) correlated with W(peak) (r = 0.91), W(LTlog) (r = 0.91), and the D(max) lactate threshold (r = 0.77, P < 0.05). In contrast, W(20-min) was significantly (P < 0.05) related to .VO(2max) (L.min(-1)) (r = 0.69) and W(LTlog) (r = 0.67). The D(max) lactate threshold was not significantly correlated to W(20-min) (r = 0.45). Furthermore, W(OBLA) was not correlated to W(90-min) (r = 0.54) or W(20-min) (r = 0.23). In addition, .VO(2max) (mL.kg(-1).min(-1)) was not significantly related to W(90-min) (r = 0.11) or W(20-min) (r = 0.47).
CONCLUSION:
The results of this study demonstrate that in subelite cyclists the relationship between maximum power output and the power output at the lactate threshold, obtained during an incremental exercise test, may change depending on the length of the TT that is completed.

 

[FrankDay]

People seem to think I am against power meters. I am not although I am against them being hyped for more than they are. However, newer power meters may offer a real advantage, especially if they give actual pedaling technique data. One of these new power meters that will give this kind of data will soon be available and it is called the iCranks. A group out of Australia have taken my product and added power meters to each cranks and have software that displays pedal torque for each crank around the circle.

This has been discussed before but the iCranks people have just upgraded their software and it now has a nice feature, they have included a box to show how much power is being lost on each revolution of the cranks. See below.

This image shows a lot of what can be gained from this extra information and the weakness of a traditional power meter that simply gives you total power. Notice the right leg is much weaker than the left on both pushing and pulling. A normal power meter that combines the two cranks and then determines balance by looking at the two downstrokes would underestimate the imbalance between these two legs by a lot since the bigger positives and smaller negatives of the left leg after 180º would get added to the right leg pushing component and the large negatives of the right leg after 180º would be subtracted from the left leg pushing component.

Next, at this point in time, the rider is losing over 10% of his positive propulsive efforts from the negative wattage on the upstroke (156 watts positive, 18 watts negative, 138 watts total). Why on earth wouldn't the rider want to eliminate that waste? How can anyone look at this and argue that negatives on the upstroke help the rider to increase power? By what mechanism would that work?

Next, notice the size of the power at 6 o'clock compared to 12, it is much larger than the 12 o'clock number. I think for this rider, the biggest gains will come from working on improving the forces across the top (without changing anything else) and, of course, improving the right leg to be the equal of the left.

I don't know how anyone could look at this data and say technique doesn't matter but, of course, some will. While it has never been shown that just gathering power helps the rider to improve beyond what he could do otherwise I think it is reasonable to assume that knowing the details of how the power is generated (or lost) can help the rider to improve. Of course, that hypothesis has yet to be proven also.

Anyhow, this software with this example is available for download by anyone with a PC. Go to http://www.icranks.com then to Technical Information then download the installer, follow the instructions to save it. There are two examples you can open and see. Example 1 is probably a PowerCranker because he has very few negatives. Example 2 (shown) is probably not, because there are a lot of negatives and he keeps trying to fix them but can't sustain it.

 

[CoachFergie]

Interesting claims from the iCrank website...

http://icranks.com/product/icranks/

1. Improve running speed/power beyond normal training benefit many are a minute per mile faster in 3 months

Never been shown in the literature.

2. Improve cycling speed/power beyond normal training benefits many are 2-3 mph faster in 6 months

A change of speed can occur for a variety of reasons.

3. Increase VO2max 15-20% improvements have been shown

This refers to the Dixon study where there was no control group. Only proves that training works.

4. Reduce risk of injury in the athlete correcting the cause of many non-impact injuries

Unproven claim.

5. Training additional muscles

Unnecessary. Why train muscles that are not involved in performance?

6. Ensuring leg and core balance

Tenuous link to actual performance and unproven that an uncoupled crank does this.

7. Improve training time management

Unproven. How does something that measures cycling performance improve training time management?

8. Faster/better rehabilitation after injury or surgery

Unproven. How does a power meter speed up the rehab or injury repair process?

9. And, there are benefits for many other athletes and non-athletes.

Yes, improves Golf performance. Unproven.

10. Now with the aid of a second generation power measuring system power improvements can be measured with industry leading accuracy in real time while also getting information important to improving technique.

Where is the research showing a change in pedalling technique leads to an improvement in power, efficiency/economy or performance?

Some rather outrageous claims for a power meter.

 

[BroDeal]

A group out of Australia have taken my product and added power meters to each cranks and have software that displays pedal torque for each crank around the circle.

Here we go. The Frank Day spam destroys another thread as he starts up the BS about pedalling technique.

 

[FrankDay]

Here we go. The Frank Day spam destroys another thread as he starts up the BS about pedalling technique.

I just happen to be able to discuss some of the details of this product. However, almost any of the new power meters that have power coming off the cranks or pedals (or shoes), measuring L and R independently should be able to incorporate this capability. The only difference the iCranks will have is they will be incorporated in the PowerCranks to help the user, who thinks it might be useful to eliminate the negatives, to eliminate the negatives and do the other things the PC's do for them.

If you don't think this additional information will be useful I would suggest you stay with what you have. I throw this out because I think power meters are about to transform themselves into providing information beyond power and that is actually useful to make the athlete better. Of course, as with everything about a power meter, none of my speculation has been scientifically proven.

 

[BroDeal]

If you don't think this additional information will be useful I would suggest you stay with what you have. I throw this out because I think power meters are about to transform themselves into providing information beyond power and that is actually useful to make the athlete better.

Uh-huh. When power measuring gets built into Gimmick Cranks then power meters become useful. How convenient.

 

[CoachFergie]

I just happen to be able to discuss some of the details of this product. However, almost any of the new power meters that have power coming off the cranks or pedals (or shoes), measuring L and R independently should be able to incorporate this capability. The only difference the iCranks will have is they will be incorporated in the PowerCranks to help the user, who thinks it might be useful to eliminate the negatives, to eliminate the negatives and do the other things the PC's do for them.

Seeing you are demanding the science, can you point us in the direction of any papers I may have missed from the Powercrank thread that show a benefit from a change of pedalling technique?

If you don't think this additional information will be useful I would suggest you stay with what you have. I throw this out because I think power meters are about to transform themselves into providing information beyond power and that is actually useful to make the athlete better. Of course, as with everything about a power meter, none of my speculation has been scientifically proven.

Not everything that matters can be counted and not everything that can be counted matters.

So you have data that racing and training with an iCrank improves performance? Do share!

 

[CoachFergie]

Power Output during the Tour de France.

Vogt S, Schumacher YO, Roecker K, Dickhuth HH, Schoberer U, Schmid A, Heinrich L.

Abstract
The aim of this study was to evaluate the demands of riding a "Grand Tour" by monitoring both heart rate and power output in 15 professional cyclists. SRM power output profiles (SRM Trainingsystem, Jülich, Germany) were collected during 148 mass start stages during the 2005 Tour de France and analyzed to establish average power, heart rate (HR) and cadence produced in different terrain categories (flat [FLT]; semi-mountainous [SMT]; mountainous [MT]). The maximal mean power (MMP) for progressively longer durations was quantified. Average HR was similar between FLT (133 +/- 10 bpm) and SMT (134 +/- 8 bpm) but higher during MT (140 +/- 3 bpm). Average power output revealed a similar trend (FLT 218 +/- 21 W [3.1 +/- 0.3 W/kg], SMT 228 +/- 22 W [3.3 +/- 0.3 W/kg], and MT 234 +/- 13 W [3.3 +/- 0.2 W/kg]). Cadence during MT was approximately 6 - 7 rpm lower (81 +/- 15 rpm) compared to FLT or SMT. During MT stages, the MMP for 1800 sec. was highest (394 W vs. 342 W) but the MMP 15 was lower (836 W vs. 895 W) compared to FLT. The data document comprehensively the power output demands during the Tour de France.

 

[CoachFergie]

Of course, as with everything about a power meter, none of my speculation has been scientifically proven.

More trolling.

http://www.ncbi.nlm.nih.gov/pubmed/15235334

When operated according to manufacturers instructions, both SRM and PT offer the coach, athlete, and sport scientist the ability to accurately monitor power output in the lab and the field. Calibration procedures matching performance tests (duration, power, cadence, and temperature) are, however, advised as the error associated with each unit may vary.

 

[CoachFergie]

Physiological and performance characteristics of male professional road cyclists.

Mujika I, Padilla S.

Abstract
Male professional road cycling competitions last between 1 hour (e.g. the time trial in the World Championships) and 100 hours (e.g. the Tour de France). Although the final overall standings of a race are individual, it is undoubtedly a team sport. Professional road cyclists present with variable anthropometric values, but display impressive aerobic capacities [maximal power output 370 to 570 W, maximal oxygen uptake 4.4 to 6.4 L/min and power output at the onset of blood lactate accumulation (OBLA) 300 to 500 W]. Because of the variable anthropometric characteristics, 'specialists' have evolved within teams whose job is to perform in different terrain and racing conditions. In this respect, power outputs relative to mass exponents of 0.32 and 1 seem to be the best predictors of level ground and uphill cycling ability, respectively. However, time trial specialists have been shown to meet requirements to be top competitors in all terrain (level and uphill) and cycling conditions (individually and in a group). Based on competition heart rate measurements, time trials are raced under steady-state conditions, the shorter time trials being raced at average intensities close to OBLA (approximately 400 to 420 W), with the longer ones close to the individual lactate threshold (LT, approximately 370 to 390 W). Mass-start stages, on the other hand, are raced at low mean intensities (approximately 210 W for the flat stages, approximately 270 W for the high mountain stages), but are characterised by their intermittent nature, with cyclists spending on average 30 to 100 minutes at, and above LT, and 5 to 20 minutes at, and above OBLA.

 

[CoachFergie]

Level ground and uphill cycling ability in professional road cycling.

Padilla S, Mujika I, Cuesta G, Goiriena JJ.

Abstract
PURPOSE:
To evaluate the physiological capacities and performance of professional road cyclists in relation to their morphotype-dependent speciality.
METHODS:
24 world-class cyclists, classified as flat terrain (FT, N = 5), time trial (TT, N = 4), all terrain (AT, N = 6). and uphill (UH, N = 9) specialists, completed an incremental laboratory cycling test to assess maximal power output (Wmax), maximal oxygen uptake (VO2max), lactate threshold (LT), and onset of blood lactate accumulation (OBLA).
RESULTS:
UH had a higher frontal area (FA):body mass (BM) ratio (5.23 +/- 0.09 m2 x kg(-1) x 10(-3)) than FT and TT (P < 0.05). FT showed the highest absolute Wmax (481 +/- 18 W), and UH the highest Wmax relative to BM (6.47 +/- 0.33 W x kg(-1)). WLT and W(OBLA) values were significantly higher in FT (356 +/- 41 and 417 +/- 45 W) and TT (357 +/- 41 and 409 +/- 46 W) than in UH (308 +/- 46 and 356 +/- 41). Scaling of these values relative to FA and BM exponents 0.32 and 0.79 minimized group differences, but considerable differences among mean group values remained. FT and TT had the highest Wmax per FA unit (1300 +/- 62 and 1293 +/- 57 W x m2), whereas TT had the highest absolute W x kg(-0.32) and W x kg(-0.79), as well as W x kg(-0.32), W x kg(-0.79), and W x m2 at the LT and OBLA.
CONCLUSIONS:
i) Scaling of maximal and submaximal physiological values showed a performance advantage of TT over FT, AT, and UH in all cycling terrains and conditions; and ii) mass exponents of 0.32 and 1 were the most appropriate to evaluate level and uphill cycling ability, respectively, whereas absolute Wmax values are recommended for performance-prediction in short events on level terrain, and W(LT) and W(OBLA) in longer time trials and uphill cycling.

 

[CoachFergie]

Cycling power output produced during flat and mountain stages in the Giro d'Italia: a case study.

Vogt S, Schumacher YO, Blum A, Roecker K, Dickhuth HH, Schmid A, Heinrich L.

Abstract
Until recently, the physiological demands of cycling competitions were mostly reflected by the measurement of heart rate and the indirect estimation of exercise intensity. The purpose of this case study was to illustrate the varying power output of a professional cyclist during flat and mountain stages of a Grand Tour (Giro d'Italia). Nine stage recordings of a cyclist of the 2005 Giro d'Italia were monitored using a mobile power measurement device (SRM Trainingssystem, Julich, Germany), which recorded direct power output and heart rate. Stages were categorized into flat (n = 5) and mountain stages (n = 4). Data were processed electronically, and the overall mean power in flat and mountain stages and maximal mean power for various durations were calculated. Mean power output was 132 W +/- 26 (2.0 W x kg(-1) +/- 0.4) for the flat and 235 W +/- 10 (3.5 W x kg(-1) +/- 0.1) for the mountain stages. Mountain stages showed higher maximal mean power (367 W) for longer durations (1800 s) than flat stages (239 W). Flat stages are characterized by a large variability of power output with short bursts of high power and long periods with reduced intensity of exercise, whereas mountain stages mostly require submaximal, constant power output over longer periods.

 

[CoachFergie]

Good sites to learn more about racing and training with a power.

The most obvious first

http://www.trainingandracingwithapowermeter.com/

http://alex-cycle.blogspot.co.nz/

http://www.cyclingpowerlab.com/Introduction.aspx

http://srm.de/

http://www.cycleops.com/

http://www.quarq.com/

 

[CoachFergie]

A great article from Dr Andy Coggan on the history of Power Meter use over the last 100 years in the form of cycle ergometers and in the last 25 years in the form of on-bike cycle ergometers.

http://www.trainingandracingwithapo...rief-history-of-training-and-racing_1025.html

I concur that one of the big features of the power meter is the improvement in specificity of preparation. Knowing the power demands of performance in an event, being able to test the rider in relation to those demands and then being able to measure if we are meeting those demands and making suitable progress!

 

[CoachFergie]

Reliability of Power Output during Dynamic Cycling

C. R. Abbiss, G. Levin, M. R. McGuigan, P. B. Laursen

Abstract
!
The aims of the present study were to determine
the influence of familiarization on the reliability
of power output during a dynamic 30-km cycling
trial and to determine the test-retest reliability
following a 6-week period. Nine trained male cyclists
performed five self-paced 30-km cycling
trials, which contained three 250-m sprints and
three 1-km sprints. The first three of these trials
were performed in consecutive weeks (Week 1,
Week 2 and Week 3), while the latter two trials
were consecutively conducted 6wk following
(Week 9 and Week 10). Subjects were instructed
to complete each sprint, as well as the entire trial
in the least time possible. Reproducibility in average
power output over the entire 30-km trial for
Week 2 and 3 alone (coefficient of variation,
CV = 2.4%, intra-class correlation coefficient,
ICC = 0.93) was better than for Week 1 and 2
(CV = 5.5%, ICC = 0.77) and Week 9 and 10 alone
(CV = 5.3%, ICC = 0.57). These results indicate that
high reliability during a dynamic 30-km cycling
trial may be obtained after a single familiarization
trial when subsequent trials are performed
within 7 days. However, if cyclists do not perform
trials for six weeks, the same level of reliability is
not maintained.

 

[CoachFergie]

Power Output Measurement during Treadmill Cycling

D. A. Coleman, J. D. Wiles, R. C. R. Davison, M. F. Smith, I. L. Swaine

Abstract
The studyaimwas to consider the use of a motorised treadmill as a
cycling ergometry system by assessing predicted and recorded
power output values during treadmill cycling. Fourteen male cyclists
completed repeated cycling trials on a motorised treadmill
whilst riding their own bicycle fitted with a mobile ergometer.
The speed, gradient and loading via an external pulley system
were recorded during 20-s constant speed trials and used to estimate
power output with an assumption about the contribution of
rolling resistance. These values were then compared with mobile
ergometer measurements. To assess the reliability of measured
power output values, four repeated trials were conducted on each
cyclist. During level cycling, the recorded power output was
257.2 ± 99.3W compared to the predicted power output of
258.2 ± 99.9W(p > 0.05). For graded cycling, therewas no significant
difference between measured and predicted power output,
268.8 ± 109.8Wvs. 270.1 ± 111.7W, p > 0.05, SEE 1.2%. The coefficient
of variation for mobile ergometer power output measurements
during repeated trials ranged from 1.5% (95% CI 1.2–
2.0%) to 1.8% (95% CI 1.5–2.4%). These results indicate that
treadmill cycling can be used as an ergometry system to assess
power output in cyclists with acceptable accuracy.

 

[CoachFergie]

Assessment Influence on
Peak Power Output and
Road Cycling Performance Prediction

Mark F. Smith

ABSTRACT
The influence of cycling assessment on peak power output and roadbased
cycling performance prediction was evaluated in twelve well-trained
amateur cyclists (mean ± SD; age, 35 ± 8 yr; body mass, 74.1 ± 6.7 kg;
stature: 181 ± 6 cm). Determining peak power output, cyclists completed a
graded i) ramp assessment on a Kingcycle air-braked ergometer
(PPOKING), ii) continuous assessment on a SRM electromagnetically-braked
ergometer (PPOSRM), and iii) discontinuous assessment on a Monark
friction-braked ergometer (PPOMON). Furthermore, a 40-km road-based
individual cycle race was completed. Throughout each, power was
measured using an SRM Training System. Despite no differences (p > 0.05)
in VO2peak across graded assessments, PPOKING (387 ± 49W) was 3.6%
higher (p < 0.05) than PPOSRM (373 ± 38W) and 9% higher (p < 0.05) than
PPOMON (352 ± 41W). Relating assessment-derived peak power output
with road-based performance (mean power: 288 ± 36W; mean time:
62:00 ± 3:13 min:sec), PPOKING (r = 0.94: p < 0.001), PPOSRM (r = 0.87; p<
0.001) and PPOMON (r = 0.90; p < 0.001) were strongly correlated to mean
power, but not time (PPOKING; r = -0.41; p > 0.05: PPOSRM; r = -0.42; p >
0.05: PPOMON; r = -0.41: p > 0.05). Independent of determination, peak
power output was strongly related to performance power and may provide
effective means of obtained training and racing intensities.
Key

 

[CoachFergie]

Optimising distribution of power during
a cycling time trial

Scott Gordon

Abstract
A simple mathematical model is used to find the optimal distribution of a cyclist’s effort during a
time trial. It is shown that maintaining a constant velocity is optimal if the goal is to minimise the
time taken to complete the course while fixing amount of work done. However, this is usually
impractical on a non-flat course because the cyclist would be unable to maintain the power
output required on the climbs. A model for exertion is introduced and used to identify the distribution
of power that minimises time while restricting the cyclist’s exertion. It is shown that, for a
course with a climb followed by a descent, limits on exertion prevent the cyclist from improving
performance by shifting effort towards the climb and away from the descent. It is also shown,
however, that significant improvement is possible on a course with several climbs and descents.
An analogous problem with climbs and descents replaced by headwinds and tailwinds is considered
and it is shown that there is no significant advantage to be gained by varying power output.
Lagrange multipliers are used solve the minimisation problems.

 

[Jeroen Swart]

Are we bored yet?

The years drag on and you guys continue to bicker on this forum using nothing but anecdotal reports to support your ideas.

Meanwhile others are out there doing real science and applying it successfully in World Class competition.

This thread should just be a copy & paste of your last dozen efforts to undermine each other with low blows and hypocritical comments backed by nothing but hot air.

Fergie, I spotted your picture recently. It was in the dictionary under the word "windbag"

 

[CoachFergie]

The years drag on and you guys continue to bicker on this forum using nothing but anecdotal reports to support your ideas.

Meanwhile others are out there doing real science and applying it successfully in World Class competition.

This thread should just be a copy & paste of your last dozen efforts to undermine each other with low blows and hypocritical comments backed by nothing but hot air.

Fergie, I spotted your picture recently. It was in the dictionary under the word "windbag"

Dr Swart, still as Professional as ever.

 

[acoggan]

others are out there doing real science and applying it successfully in World Class competition.

What, you mean like this?

 

[veganrob]

The years drag on and you guys continue to bicker on this forum using nothing but anecdotal reports to support your ideas.

Meanwhile others are out there doing real science and applying it successfully in World Class competition.

This thread should just be a copy & paste of your last dozen efforts to undermine each other with low blows and hypocritical comments backed by nothing but hot air.

Fergie, I spotted your picture recently. It was in the dictionary under the word "windbag"

Perhaps you could enlighten us then. You have not added anything to the discussion.

 

[acoggan]

Perhaps you could enlighten us then. You have not added anything to the discussion.

Dr. Swart was the lead author of this strawman study:

http://www.ncbi.nlm.nih.gov/pubmed/19204572

 

[FrankDay]

Dr. Swart was the lead author of this strawman study:

http://www.ncbi.nlm.nih.gov/pubmed/19204572

Do you guys know how to have a civilized discussion? Strawman study? Anyhow Dr. Coggan, why don't you enlighten us all as to how you would design a study to look at whether a power meter provides any extra benefit to the cyclist.

 

[acoggan]

Do you guys know how to have a civilized discussion?

Phooey.

Strawman study? Anyhow Dr. Coggan, why don't you enlighten us all as to how you would design a study to look at whether a power meter provides any extra benefit to the cyclist.

For starters, I wouldn't design it so as to almost guarantee no difference compared to using heart rate.

EDIT: In the present context, Swart et al.'s concluding sentence is rather interesting:

"Coaches who are unable to monitor progress frequently should prescribe training based on heart rate, when intervals are performed under stable conditions..."

The thoughts that come to mind are:

1) When using a powermeter (but not a heart rate monitor), training is testing and testing is training; and

2) most people don't do their intervals on an ergometer in a climate-controlled laboratory.