Power meters · Public discussion

Training with a Powermeter

fergie · 2006-02-20T23:39:13+00:00

Been training with a Powertap for the last 4 weeks. Here are my observations on it's benefits. Just riding with a powermeter you really get an appreciation of how variable you power output can be. Sitting on 30kph the power could be sitting on 175 watts then jump to 220 as the road slightly inclines then drop to 155 as a car goes past or below 100 if a long truck goes past (see why British TTs use busy Motorways). Because of the variability I tend to use ave power for long rides and long intervals instead of trying to hold watts constant. Even on a windtrainer I find it hard to hold on. Did a ramped test and trying to hold a set wattage was a nightmare. I assume that a Kingcycle (power measuring indoor trainer) updates power at 2-5sec intervals rather than the 1sec updates I use on my Powertap as it's easier holding a constant power using the Kingcycle. I am finding the CyclingPeaks software the best programme to analyse my data. The Powertap software and Poweragent software doesn't cut it and I really like the ease of highlighting any section of my ride and the ability to use the programme as a training diary. As well as long rides I have been trying various intervals using Andy Coggan's (ex physiologist, coach and competitor) levels of training. These are based on long endurance rides, medium rides at tempo, long intervals around your threshold, medium intervals around your vO2max, short intervals above the vO2max and very short sprints. From the charts produced on Cycling Peaks I can work my max and ave power for each effort. The shorter the effort the more important the peak power while for the more aerobic efforts the ave power is more important. The Cycling Peaks software can also determine your max power for any duration. This is a good way to test for improvement over a season although you do have to take into account that much of the power may have come from anaerobic sources. This is why I think I will do a test for each type of aerobic effort rather than base my training off the max mean power for any duration. From this I can try and add 5 watts every subsequent time I do an effort. The other option is to use the max power for the duration and start an interval session at a percentage below this. Various sources have suggested 80-85% is a good figure to start at. If I don't have much luck with the TTs then I will switch to this approach. I did use lactate testing to determine HR training zones but can now see the high variability with HR and how many factors affect HR in comparison to power. Also I have concerns with the variability in results when doing lactate testing. Andy Coggan has suggested using the Dmax method of determining a threshold point from the lactate curve and from the tests I have performed on several riders has proved to be a better predictor of performance than threshold's determined by assessing a turnpoint on the lactate curve, using 2 or 4mmol of lactate, power at vO2max or max minute power. Dmax has also correlated highly with the Functional Threshold. This is based on max mean power one can sustain for 60min. One could do a 60min TT, or take the average power from a 60min road race as other ways to determine this point. This figure predicted performance in my riders in both 2k Pursuit and road TT better than any other figure. Buggered if I am doing a 60min TT though so will stick with Dmax or pulling info from road races. The meter can also be used to track ones progress on various courses. Measuring ave power on a TT course can give you a constant assessment of progress even if weather conditions vary from week to week. I rode a hill section two weeks ago and yesterday was pleased to have gone up there at 10 watts higher than last time. Although you can't fit my Powertap to a track bike I can see why all the top track teams use SRM on the track. The data is invaluable for knowing how one is going. You can also use the SRM to equate power from one track to another. It's only been 4 weeks but learnt heaps already. NZ Track Coach Terry Gyde has suggested it takes up to year to fully appreciate the value of training with power so I look forward to the next 48 weeks! Hamish Ferguson Cycling Coach *Dmax http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=1459746&dopt=Abstract *Andy Coggan Training with power http://www.midweekclub.ca/articles/coggan.pdf *MAP test http://www.cyclingnews.com/fitness/?id=powerstern

Started by fergie · 20 February 2006 · Last activity 21 February 2006 · 8 posts · 1,883 views

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Original section: Power meters
Published: 20 February 2006
Last activity: 21 February 2006
Original author: fergie
Posts: 8
Discussion status: Public discussion
Total views: 1,883
Views / 30 days: 0
Topics: Cadence Power meters VO2 max Heart rate training Indoor trainers Training with power

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Original post
fergie
Archived post

20 February 2006, 23:39 UTC #1

Been training with a Powertap for the last 4 weeks. Here are my observations on it's benefits.
Just riding with a powermeter you really get an appreciation of how variable you power output can be. Sitting on 30kph the power could be sitting on 175 watts then jump to 220 as the road slightly inclines then drop to 155 as a car goes past or below 100 if a long truck goes past (see why British TTs use busy Motorways).
Because of the variability I tend to use ave power for long rides and long intervals instead of trying to hold watts constant. Even on a windtrainer I find it hard to hold on. Did a ramped test and trying to hold a set wattage was a nightmare. I assume that a Kingcycle (power measuring indoor trainer) updates power at 2-5sec intervals rather than the 1sec updates I use on my Powertap as it's easier holding a constant power using the Kingcycle.
I am finding the CyclingPeaks software the best programme to analyse my data. The Powertap software and Poweragent software doesn't cut it and I really like the ease of highlighting any section of my ride and the ability to use the programme as a training diary.
As well as long rides I have been trying various intervals using Andy Coggan's (ex physiologist, coach and competitor) levels of training. These are based on long endurance rides, medium rides at tempo, long intervals around your threshold, medium intervals around your vO2max, short intervals above the vO2max and very short sprints.
From the charts produced on Cycling Peaks I can work my max and ave power for each effort. The shorter the effort the more important the peak power while for the more aerobic efforts the ave power is more important.
The Cycling Peaks software can also determine your max power for any duration. This is a good way to test for improvement over a season although you do have to take into account that much of the power may have come from anaerobic sources.
This is why I think I will do a test for each type of aerobic effort rather than base my training off the max mean power for any duration. From this I can try and add 5 watts every subsequent time I do an effort.
The other option is to use the max power for the duration and start an interval session at a percentage below this. Various sources have suggested 80-85% is a good figure to start at. If I don't have much luck with the TTs then I will switch to this approach.
I did use lactate testing to determine HR training zones but can now see the high variability with HR and how many factors affect HR in comparison to power. Also I have concerns with the variability in results when doing lactate testing.
Andy Coggan has suggested using the Dmax method of determining a threshold point from the lactate curve and from the tests I have performed on several riders has proved to be a better predictor of performance than threshold's determined by assessing a turnpoint on the lactate curve, using 2 or 4mmol of lactate, power at vO2max or max minute power.
Dmax has also correlated highly with the Functional Threshold. This is based on max mean power one can sustain for 60min. One could do a 60min TT, or take the average power from a 60min road race as other ways to determine this point. This figure predicted performance in my riders in both 2k Pursuit and road TT better than any other figure. Buggered if I am doing a 60min TT though so will stick with Dmax or pulling info from road races.
The meter can also be used to track ones progress on various courses. Measuring ave power on a TT course can give you a constant assessment of progress even if weather conditions vary from week to week. I rode a hill section two weeks ago and yesterday was pleased to have gone up there at 10 watts higher than last time.
Although you can't fit my Powertap to a track bike I can see why all the top track teams use SRM on the track. The data is invaluable for knowing how one is going. You can also use the SRM to equate power from one track to another.
It's only been 4 weeks but learnt heaps already. NZ Track Coach Terry Gyde has suggested it takes up to year to fully appreciate the value of training with power so I look forward to the next 48 weeks!
Hamish Ferguson
Cycling Coach
*Dmax
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=retrieve&db=pubmed&list_uids=1459746&dopt=Abstract
*Andy Coggan Training with power
http://www.midweekclub.ca/articles/coggan.pdf
*MAP test
http://www.cyclingnews.com/fitness/?id=powerstern

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frenchyge
Archived post

21 February 2006, 00:36 UTC #2

fergie said:
Been training with a Powertap for the last 4 weeks. Here are my observations on it's benefits.

Good comments, and I'm glad to hear you're having some success with it. I hope this doesn't mean you're going to become a career *trainer* like some of the rest of us who just want to talk about FT-this and MP20-that. 😉 It's still race results that matter, right?
fergie said:
Just riding with a powermeter you really get an appreciation of how variable you power output can be. Sitting on 30kph the power could be sitting on 175 watts then jump to 220 as the road slightly inclines then drop to 155 as a car goes past or below 100 if a long truck goes past (see why British TTs use busy Motorways).

A you aware of the effect of 'precession' that affects the powertap readings? The PT records the data every 1.26 seconds, but the display updates every 1 second. The mismatch between the recording rate and the display rate *creates* jumps in the power readout every few seconds as the two go in and out of synch. Setting a longer display averaging interval not only smooths power fluctuations caused by the rider, but the precession effects as well.

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jerryz
Archived post

21 February 2006, 04:41 UTC #3

frenchyge said:
Good comments, and I'm glad to hear you're having some success with it. I hope this doesn't mean you're going to become a career *trainer* like some of the rest of us who just want to talk about FT-this and MP20-that. 😉 It's still race results that matter, right?
A you aware of the effect of 'precession' that affects the powertap readings? The PT records the data every 1.26 seconds, but the display updates every 1 second. The mismatch between the recording rate and the display rate *creates* jumps in the power readout every few seconds as the two go in and out of synch. Setting a longer display averaging interval not only smooths power fluctuations caused by the rider, but the precession effects as well.

At least for me I found that I became a smoother pedaler. Or at least power output became more consistent as time went on.

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frenchyge
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21 February 2006, 14:11 UTC #4

jerryz said:
At least for me I found that I became a smoother pedaler. Or at least power output became more consistent as time went on.

The effect is also a function of cadence, so it is possible to mitigate the jumpiness by pedalling in certain ways. While it makes the display look nicer, I'm not sure that's beneficial to the rider.

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jerryz
Archived post

21 February 2006, 15:49 UTC #5

frenchyge said:
The effect is also a function of cadence, so it is possible to mitigate the jumpiness by pedalling in certain ways. While it makes the display look nicer, I'm not sure that's beneficial to the rider.

Not sure I understand the function of cadence statement. For instance I find that overall output is smoother, on both my powertap and my ergomo, when my cadence is above 90. I assumed that had to do with the fact that it required less force per stroke at higher cadences. Hence a smoother output? And since a higher cadence is beneficial..... Or am I on the wrong track completely? If so how?

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acoggan
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21 February 2006, 16:09 UTC #6

jerryz said:
Not sure I understand the function of cadence statement. For instance I find that overall output is smoother, on both my powertap and my ergomo, when my cadence is above 90. I assumed that had to do with the fact that it required less force per stroke at higher cadences. Hence a smoother output? And since a higher cadence is beneficial..... Or am I on the wrong track completely? If so how?
The PowerTap calculates power as a function of time, not as a function of pedal cycles. Thus, except at particular "magic" cadences (i.e., 47.6, 95.2, 142.8 rpm), it constantly over- or underestimates your true power output as a result of including/excluding partial pedal revolutions from the calculation. This is the "precession" effect to which frenchyge was alluding.

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frenchyge
Archived post

21 February 2006, 16:38 UTC #7

acoggan said:
The PowerTap calculates power as a function of time, not as a function of pedal cycles. Thus, except at particular "magic" cadences (i.e., 47.6, 95.2, 142.8 rpm), it constantly over- or underestimates your true power output as a result of including/excluding partial pedal revolutions from the calculation. This is the "precession" effect to which frenchyge was alluding.
Right, and the closer you get to one of the "magic cadences", the smoother the display will appear, even without changing the application of force - on the PT at least, not sure about the Ergomo.

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jerryz
Archived post

21 February 2006, 17:04 UTC #8

frenchyge said:
Right, and the closer you get to one of the "magic cadences", the smoother the display will appear, even without changing the application of force - on the PT at least, not sure about the Ergomo.

Ah. I see. So as I got my avg cadence closer and closer to 95 the display became smoother as a function of the precession not as a function of smoother application of power. Then why does it still seem to hold true for my new ergomo?

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