Question for the Ex.Phys Boffin(s) (AWC, Power-Duration)

amartinez

With my own data the fit also was quite good and I was curious of others (thanks Alex for your data), it could be useful to model longer durations for which the critical power model doesn't seem to work anymore.
The formula seems to work quite well for running and swimming.

The Slope is related to what Riegel called "Fatigue Factor" but I think it doesn't have a direct Ex.Phys. interpretation.

Anyway I don't have answers for your questions, no Ex.Phys Boffin here

The article in American Scientist can be found her: Athletic Records and Human Endurance

acoggan

FWIW, I would refer to it as "stamina" or "endurance", i.e., the extent to which one can avoid slowing down as duration progressively increases. (I would also hypothesize that changes in this slope are related to long-term CTL, but that's a bit of a different question.)

Steve_B

Oops. Yeah, you (and Andy) are right. I was thinking of the plot of energy vs. time where the slope is CP - the rate of change of energy vs. time is power - and didn't think. This is power vs. time (Ok, log transformed).

Alex Simmons

OK - I know that's another question but I just wanted to be clear what you mean by long term CTL.

How long it's been up there in the clouds and not having just ascended to that level perhaps?

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amartinez

Nice, lets call it ei=endurance index, would be an insteresting value to track ?

A nice math property of this "endurance index" is it fully describe the "aspect/shape" of the power-duration relation for long(er) durations, when coupled with FT we could estimate any other MMP:

MMPt = FT * t^ei
where:
t is duration in hours
ei is the slope of the log(MMP)-log(Duration) relationship for (longer, >10' for ex.) durations (provided we have a good fit)

Just thinking in loud voice, are there real studies about this ?

acoggan

I suppose "long term CTL" is a bit redundant, eh?

What I meant was that in addition to moving the power-duration curve upward (well, the aerobic portion, anyway), endurance training also tends to flatten the curve (i.e., decrease the negative slope of the terminal component), and it is this latter effect that I would hypothesize is most impacted by how many miles/hours/years you have under your belt.

At the extreme, I think you can see this in the performance of young pursuiters (e.g., Tyler Phinney), who can often approach the times of the best in the world at 4 km, but lack the stamina to compete at the same level in 3 wk stage races. As such talents continue to train (and reach maturity...development undoubtly plays a role), they may (or may not) get a little faster at shorter durations, but they get a lot faster at longer durations.

acoggan

I know that there have been various attempts to develop equations describing the speed-duration (or power-duration) relationship over very long periods of time (e.g., in migratory birds). I'd have to dig around a bit, though, to see what has emerged from such efforts.

Steve_B

Ummm...dare I say, "raise the left and then fill the right"?

doctorSpoc

i'm not one of the "boffins" but i'll chime in on what i've observed anecdotally..

i'm not going to quantify it because i don't know how to separate which portion is coming from AWC and the degree of the effect is dependent one's AWC ability but... i know that as long as for the preceding period i keep intensity slightly below FTP... the ending period i can bang out a good ~10 min a fair bit above FTP... and the last 5 mins far in excess of FTP... the ave power for the total period far in excess of what i could do for an isopower interval (dependent on length of intervals)... in fact for me, if i had started the interval at the ave power for the total time period i probably wouldn't be able to complete the interval at that power...

but i if i'm interpreting you question properly (and not sure if i am)... AWC has less potential to effect ave power for the total duration the longer the duration mostly because that ~10 mins that you can actually use you AWC ability effectively represents a smaller and smaller percentage of the total time the longer and longer you go out because that number is fixed.. 10mins/20mins is 50%, 10mins/240mins is 4%... so AWC is of little effect for a 2hr interval..

i've found if you are riding an isopower interval at FTP or above your ability to even utilize AWC ability diminishes rapidly... if you ride all but the last ~10mins or so slightly under FTP you can more than make up for it on the back end as long as the 10min is significant portion/percentage of the entire interval and you AWC ability is such that, that 10mins contributes significantly to the ave power for the interval...

Steve_B

I think that you have to be careful about what your intentions are and data you apply to the curve. The original idea (or at least what the guys who wrote about horse racing and human running tried to do) was to predict times at various distances. Alex applied his MMP data to make a curve for us here. As a prediction of performance, that might not work too well. If I started an effort at my 5-minute best power and tried to hold it for as long as possible, I doubt that I would be able to do my best power at succeeding durations. OTOH, if you are simply using the MMP data to derive "EI" (as defined above) as an index to track and not using it as a predictor of performance, that's something else.

Do horses understand proper pacing? Maybe we should ask one.

Steve_B

That probably suggests a NP for any duration far in excess of the AP for that same duration, which is not unheard of. Is there a motivation factor at work here?

doctorSpoc

i think some of it might be motivational... but i think it's physiological as well... i blow up doing isopower intervals at ave powers less than 'ramped' ave power for ramped intervals and the RPE is far greater for the isopower intervals than for the 'ramped'

e.g. my FTP is in the 250 range... just from memory, if i was going to do a 20min interval at say 260W i would do something like this.. 1st 5mins at 240W, next 5mins ramp to 260W... ramp to 270-280W... ramp to 300W+... if i started at 260 i'd blow up at about 10mins... wouldn't have a snowballs chance in hell of completing that interval..

daveryanwyoming

I've found the same thing, particularly in training, less so during long TTs. My best AP for long efforts this winter all happened during ramped workouts like you describe. More than once I'd try a subsequent workout (after some easier days) right at the AP for the ramped effort and usually blew early but then did very well in another ramped effort a few days later.

I definitely think some of it is mental for me and some is probably related to warmup. I try to get a really solid and fairly long warmup for time trials and that seems to help me get into target pace more quickly. But regardless of the reason ramped efforts do seem to work really well in training and I almost always finish the last 5 to 10 minutes well above my target AP which is a nice kick to a long steady interval.

-Dave

acoggan

You can, but "lift and flatten" is much more appropriate (esp. since you can maximize glycogen stores - i.e., "fill" - by training in a manner that actually steepens the curve).