Power Duration Curve

Krank
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Power Duration Curve

Postby Krank » Fri Jan 01, 2016 1:25 pm

Hello All.

Keen to read your thoughts on power duration curve.

I understand this is likely to be different for both indoors and outdoors. I have read that many riders output more power for short durations indoors than outdoors, perhaps because it allows more muscle mass to be engaged as you're working around more of the pedal stroke, so for short durations where that is a limiter, the indoor trainer enables to output more power.

But for longer durations, the extra muscles being used are less efficient and fatigue more quickly, so power output drops off a lot more quickly than it does outdoors.

Some riders think it's much better to simply look at the effectiveness of training sessions in terms of adaptation and fatigue, based on how you feel in the days after each session, and work to that rather than testing power over a given duration and setting targets as %s of that. It is noted by riders, that the difference between a session being too hard and too easy can be quite small, so they cannot see that mindlessly targeting a % of a test result is ever going to accurately identify the optimal power to perform a session at.

Keen to hear your thoughts on using power as a measure of progress vs perceived effort?

What effective information do you obtain from the power duration curve to assist with your training regime?


Krank

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Alex Simmons/RST
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Re: Power Duration Curve

Postby Alex Simmons/RST » Fri Jan 01, 2016 3:44 pm

I use the power duration curve and associated models and PD metrics to inform about a rider's phenotype, their relative strengths and areas for development (keeping in mind the specific demands of their goal events), helping to decide when to target specific elements of fitness and for constantly tracking progress on these key aspects of fitness, in particular a rider's threshold power, functional reserve capacity and their Pmax (peak power capability).

It's now possible to constantly track subtle variations in each of these key elements of fitness with new power duration models.

e.g. for one client recently I could see that we had attained good steady progress with threshold power but it was time to give them more focus on developing their Pmax as it was a limiter for them. After a nearly a month of including some specific work, their Pmax is up 7% while threshold power has been maintained (actually threshold was also slightly up which is pretty hard to do). And it's showing as their ability and results when the pointy end of a race comes around has improved nicely.

Setting of power targets isn't something that requires a high level of precision - all you are after is that work is done at about the right level of effort which will be a power range, and duration. Using power for guiding intensity of effort is an example of what I call a low-fi application of power meter and power data, and that's why perceived effort can in large parts work quite well. PE is not so good for shorter duration efforts in and around a few minutes duration, that's where an indoor trainer or a track and stopwatch can help if you don't have power and struggle to pace well. Sprints are all out, no need for power to guide, just record and report.

The more in depth analysis and understanding of PD metrics and how to use them as actionalble intelligence however is a bit more hi-fi.

As to indoor/outdoor power, there are many aspects to what causes differences. When it comes to training, you simply adjust power / effort to the conditions, after all, "alls you can do is alls you can do".

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g-boaf
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Re: Power Duration Curve

Postby g-boaf » Fri Jan 01, 2016 3:52 pm

There is a graph in training peaks that tracks your power over certain durations, so you can see how you are going. But it depends on what you are doing on the bike.

I don't look at anything less than 30 second power. :oops:

But I can do alright over 5, 10, 20, 30, 60 minutes or more.

I don't really pay that much attention to it at the moment. Just going out a couple of times a week in a regular route riding as hard as I can, then see what power and time I got.

Not so easy to do outdoors as you can get so many variables. But it is fun - and as long as I feel at the end of it like I couldn't possibly have done any more than that, I'm happy.

Edit: See above reply. All you need to know.
Last edited by g-boaf on Fri Jan 01, 2016 5:11 pm, edited 1 time in total.

Krank
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Re: Power Duration Curve

Postby Krank » Fri Jan 01, 2016 4:54 pm

Thanks guys.

great responses and gives me more to research.

What impact does Erg mode have on the Power Duration Curve ?

keank

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Re: Power Duration Curve

Postby Alex Simmons/RST » Fri Jan 01, 2016 6:28 pm

Krank wrote:Thanks guys.

great responses and gives me more to research.

What impact does Erg mode have on the Power Duration Curve ?

keank
Unrelated concepts.

The PD curve is simply a means of displaying what power bests you have attained for each duration from seconds out to hours. Whether or not it or models derived from it are reflective of actual capability depends on whether the data includes sufficient maximal or near maximal efforts across a range of durations.

Erg mode is simply a means of having a trainer provide a pre-set resistance level.

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Re: Power Duration Curve

Postby Bluejay87 » Fri Jan 01, 2016 7:56 pm

Alex Simmons/RST wrote:
It's now possible to constantly track subtle variations in each of these key elements of fitness with new power duration models.
Can I just ask exactly what you mean by that?

Do you mean using something like the extended CP model on golden cheetah and comparing actual bests to predicted bests to find areas to improve?

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Re: Power Duration Curve

Postby Alex Simmons/RST » Sat Jan 02, 2016 7:10 am

Bluejay87 wrote:
Alex Simmons/RST wrote:
It's now possible to constantly track subtle variations in each of these key elements of fitness with new power duration models.
Can I just ask exactly what you mean by that?

Do you mean using something like the extended CP model on golden cheetah and comparing actual bests to predicted bests to find areas to improve?
By tracking daily changes in FTP, FRC and Pmax using WKO4 and examining the relative PD curve expressed in a strengths and weaknesses chart format.

The GC equivalent of the former would be a chart tracking changes in CP, W' and P-max but I'm not sure if you can do the latter in GC as it requires a version of power profiling based on population PD curves and phenotype classification.

I'm a little less confident in the robustness of the CP model then the WKO model, but that's another discussion entirely.

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Re: Power Duration Curve

Postby Mjainoz » Sat Jan 02, 2016 8:16 am

Krank wrote:Hello All.

Keen to read your thoughts on power duration curve......

.....

What effective information do you obtain from the power duration curve to assist with your training regime?


Krank
As I was reading the OP I was thinking oh this needs Alex's insight.

First reply is from Alex :).

Bluejay87
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Re: Power Duration Curve

Postby Bluejay87 » Sat Jan 02, 2016 12:46 pm

Thanks Alex. I'll have to read more deeply about this stuff. Can you recommend any reading?

Mjainoz
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Power Duration Curve

Postby Mjainoz » Sat Jan 02, 2016 1:16 pm

Bluejay87 wrote:Thanks Alex. I'll have to read more deeply about this stuff. Can you recommend any reading?
jumping In. Alex's web site. See link above. Or alex-cycle.blogspot.com.au.
FYI. I've only met Alex a few times ... doubt he knows who I am - but his stuff on forums around the world is gold and its free. We are all lucky to get his insights IMO).
Also - I'm pretty new on this forum but looks like I'll be hanging around - it's good.

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Re: Power Duration Curve

Postby Bluejay87 » Sat Jan 02, 2016 3:34 pm

Yes and that google groups he runs is very interesting. Even saw dcrainmaker posting there

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Alex Simmons/RST
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Re: Power Duration Curve

Postby Alex Simmons/RST » Sat Jan 02, 2016 6:54 pm

Google WKO4 power duration model and you'll find a bunch of stuff from the scientific basis for the model by Andy Coggan, slide presentations covering many aspects, through to videos and items on practical usage.

Krank
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Re: Power Duration Curve

Postby Krank » Mon Jan 04, 2016 7:11 pm

Thanks Alex - Good stuff!

Krank

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