max watts for different lengths of time.

neeb

If you can maintain an average of x watts for 40 mins, is there an equation that will predict what you should be able to maintain for an hour and a half, or for 15 mins? Or does it depend on individual metabolism? Or both?

Anonymous

Whatever the equation works out for anyone, I can do 12 Watts more.

rake

max power and stamina are two different things. a sprinter is no good at a marathon etc.

neeb

Yeah, I guess stamina determines how max power varies over different periods. Maybe you would need at least two reference points then, e.g. if you know what watts you can maintain for 10 mins and for 30 mins, could you get a good estimate of what it would be for an hour?

Or is it all just completely unpredictable and something you need to find out yourself for every particular length of maximum effort?

Bhima

You'll need more than 2 data points because the power-duration curve is not linear. As you decrease time, the maximum possible average power increases exponentially.

I've just started looking at this and currently have 4 data points. On my rollers, i'm using speed because there is no percievable difference in the rate of resistance increase as speed changes:

My 60 minute speed is 92% of my 20 minute speed (need to work on this)
My 20 minute speed is 95% of my 10 minute speed
My 10 minute speed is 84.2% of my 1 minute speed
My 1 minute speed is 71% of my 5 second speed.

If I were to graph this, it would still be very hard to predict other powers. I don't think the graph would look the same for everyone because one who specializes at a particular power (sprinters for example) would have a different curve shape as you approach the said power.

Pokerface

neeb wrote:

Yeah, I guess stamina determines how max power varies over different periods. Maybe you would need at least two reference points then, e.g. if you know what watts you can maintain for 10 mins and for 30 mins, could you get a good estimate of what it would be for an hour?

Or is it all just completely unpredictable and something you need to find out yourself for every particular length of maximum effort?

With SOME variation, you can estimate your hour wattage (known as Functional Threshold Power - FTP) based on a 20 minute effort. Somewhere between 88% and 95% of your 20 minute power.

So, if you can do 300 watts average for 20 minutes, your FTP should be in the range of 264 to 285 watts.

This is a very simplistic calculation as there are specific protocols for testing that many people follow before doing their 20 minute effort.

And no matter how many times I do it, NapD always manages to do at least 12 watts more than me.

MatthewBulmer

http://rick.mollprojects.com/power_mete ... index.html

Scroll down to section on 'CP Analysis' and the attached Excel spreadsheet and paper by Andy Coggan.

bahzob

neeb wrote:

If you can maintain an average of x watts for 40 mins, is there an equation that will predict what you should be able to maintain for an hour and a half, or for 15 mins? Or does it depend on individual metabolism? Or both?

No there is no equation that works from such little data as individuals will vary hugely. Further once you get past 1.5 hours of effort or so variables come into play (e.g. level of glycogen, efficiency of your metabolism, food/drink)

There are ways to guesstimate your 1 hour power from a shorter duration effort but they are hit and miss and mainly used for bragging rights.

The spreadsheet above relies on you doing the real tests up to at least an hour. Its worth doing though as this will help you know what sort of power profile you have (e.g. sprinter, all-rounder, TT) which can be useful in training and deciding which events will or wont suit you .

More here
http://home.trainingpeaks.com/articles/cycling/power-profiling.aspx

neeb

All very interesting, thanks.

Most of my maximal efforts on the trainer are over about 20mins or 40mins, I need to try 5mins and 1 hour sometime. The problem of course is that you need to do it a few times before you know how to pace yourself and thus get the best time for that duration, e.g. I know what wattage to aim for when I am going for 40 mins, but if I tried to maintain that for an hour I would probably lose power towards the end and get a slower time than if I had aimed for a slightly lower wattage to begin with.

Another question - should you always be aiming for a flat power profile over a given duration, i.e. will you generally achieve the fastest time by keeping the watts constant, or by starting more powerfully and fading, or starting weaker but saving energy for a final effort? In my experience it seems that keeping it constant works best, assuming you know what the maximum is that you can sustain without fading.

Alex_Simmons/RST

neeb wrote:

Another question - should you always be aiming for a flat power profile over a given duration, i.e. will you generally achieve the fastest time by keeping the watts constant, or by starting more powerfully and fading, or starting weaker but saving energy for a final effort? In my experience it seems that keeping it constant works best, assuming you know what the maximum is that you can sustain without fading.

That is highly dependent upon the expected duration of effort and the terrain, and to a lesser extent conditions as well.

bahzob

neeb wrote:

All very interesting, thanks.

Most of my maximal efforts on the trainer are over about 20mins or 40mins, I need to try 5mins and 1 hour sometime. The problem of course is that you need to do it a few times before you know how to pace yourself and thus get the best time for that duration, e.g. I know what wattage to aim for when I am going for 40 mins, but if I tried to maintain that for an hour I would probably lose power towards the end and get a slower time than if I had aimed for a slightly lower wattage to begin with.

Another question - should you always be aiming for a flat power profile over a given duration, i.e. will you generally achieve the fastest time by keeping the watts constant, or by starting more powerfully and fading, or starting weaker but saving energy for a final effort? In my experience it seems that keeping it constant works best, assuming you know what the maximum is that you can sustain without fading.

I would encourage you to do the tests at other durations. They times are not altogether arbitrary, they do correspond (to some degree and depends on event) to the different aspects of your body that most will be aiming to train. e.g. many will be doing 1 and 5 minute intervals in the most intense periods of their training schedule a month or so before key event. Though measures you take now may not be fully accurate they should be useful to set baselines for these. Also they can be good motivators.

That said doing a 60 minute test on a trainer is as much a test of mind as body. It may also not be that reliable. I and many others find it difficult to replicate on road power indoors because things like staying cool/comfortable are hard. I have 2 sets of "PBs" one on trainer one on road. That way I can more easily compare like with like. So I would not be too worried in your shoes if you dont do a 60 minute test on the trainer, but would suggest you did one on the road when conditions allow. (Simplest way to do this is enter some 25 mile time trials, even if you dont have a powermeter speed for these will be a good indication of FTP improvement or otherwise and you can then use the same course for intervals like 2x20s) (Note: Aerodynamics play a big part as well. To compare like for like position should be the same each ride. This will also save you a lot of money as once you start to worry about aerodynamics you take the first steps down a very slippery and expensive slope...:))

Re the power profile: That's a complete subject in itself. Very simply a flat or negative split (second half slightly more power than first) is ideal if conditions are ideal and the road is dead flat. However this is never the case. I took part in a university study on a hilly course to check a flat power profile against one where power was (indirectly, not linearly) proportional to gradient and the latter gave significantly faster times for same average power. (And that was keeping position the same. As noted above things are even more complicated because when it comes to speed there is a compromise between the position that is most aero and the one thats most powerful)

All this is another reason why training on a trainer is great but not a substitute for riding on road if your goal is fastest time for a given event.

Alex_Simmons/RST

bahzob wrote:

I took part in a university study on a hilly course to check a flat power profile against one where power was (indirectly, not linearly) proportional to gradient and the latter gave significantly faster times for same average power.

That's interesting and suggests to me the average isopower effort was not the maximal power riders were actually capable of, given that they were capable of same average power when riding with a highly variable pacing strategy.

IOW - the Normalised Power for the variable effort would have been significantly higher than for the isopower effort, indicating the level of strain was not the same.

neeb

Thanks for that advice. At this time of year where I am (Helsinki), the trainer is the only realistic option (cyclo-cross or MTB at -15C just doesn't appeal, although people do it...). I have the tacx fortius which I use with the RLV DVDs (also a very large fan and good ventilation). I'm always doing simulated climbs on the longer efforts as for some reason it's less soul-destroying to maintain the power that way. It would be quite easy to design a course (say on the Stelvio or Ventoux) that involved an hour of continuous climbing, and I've already been doing 40min continuous maximum efforts so I know what it's going to be like psychologically....

It always takes me a few weeks to adapt in the autumn and spring going from the road to the trainer and back again, I'm doing much more intense, continuous efforts for shorter periods on the trainer. No way could I put up with the boredom of riding for 2 hours on the trainer at lower effort... I need about 6 weeks every spring to get the road fitness back again but the climbing simulation during the winter really gives me a boost on the hills which lasts most of the summer and then fades slightly towards the autumn.

bahzob

Alex_Simmons/RST wrote:

bahzob wrote:

I took part in a university study on a hilly course to check a flat power profile against one where power was (indirectly, not linearly) proportional to gradient and the latter gave significantly faster times for same average power.

That's interesting and suggests to me the average isopower effort was not the maximal power riders were actually capable of, given that they were capable of same average power when riding with a highly variable pacing strategy.

IOW - the Normalised Power for the variable effort would have been significantly higher than for the isopower effort, indicating the level of strain was not the same.

That's right. To allow easy control rides were at sub-max power (around 255W av 325W peak for most, 325W, 440W peak for a few elites) and the course was only 2.5 miles. To allow comparison the actual power figures were normalised to a consistent standard but its not clear if this is the same as saying that the normalised power for the rides is the same.

And even then the relationship between normalised power and actual perceived strain is not at all clear cut. In my case for 50s and above (so sub threshold) I find a flat power (low VI) is easiest and fastest. For 10s however (so above threshold) I find I am both faster and find the ride "easier" (well a bit less hard) if I have a higher VI (so 320W-325NW feels if anything tougher to actually do than 320W-335W). Our courses are rolling and this may be due to the effect noted in experiment above or just simply its mentally easier to attack the ups and relax on the downs a bit (think its certainly a bit of the latter as the worst 10s of all are those with cross winds where VI is highest but effort very difficult to control as switch)

Whatever its for sure there's no magic formula that will suit all. Think its more a case of knowing what the variable are then sucking and seeing which work best for a given rider and given conditions.

bahzob

neeb wrote:

Thanks for that advice. At this time of year where I am (Helsinki), ...

Greetings to Helsinki,, weather here in UK feels like we are there too at the moment..

Alex_Simmons/RST

bahzob wrote:

That's right. To allow easy control rides were at sub-max power (around 255W av 325W peak for most, 325W, 440W peak for a few elites) and the course was only 2.5 miles. To allow comparison the actual power figures were normalised to a consistent standard but its not clear if this is the same as saying that the normalised power for the rides is the same.

Well that's a bit of a shame really, since:
i. simple physics already tells us that appropriately variable power on variable terrain for the same average power will be faster (hence that part of the study was pretty superfluous), but more importantly
ii. the strain v power relationship is curvelinear, and so a comparison of such ride strategies using same sub-maximal average power is not really all that useful.

What we want to know is what happens when riders ride at their maximal effort for the duration using each strategy (iso-power versus variable power).

bahzob wrote:

And even then the relationship between normalised power and actual perceived strain is not at all clear cut. In my case for 50s and above (so sub threshold) I find a flat power (low VI) is easiest and fastest. For 10s however (so above threshold) I find I am both faster and find the ride "easier" (well a bit less hard) if I have a higher VI (so 320W-325NW feels if anything tougher to actually do than 320W-335W). Our courses are rolling and this may be due to the effect noted in experiment above or just simply its mentally easier to attack the ups and relax on the downs a bit (think its certainly a bit of the latter as the worst 10s of all are those with cross winds where VI is highest but effort very difficult to control as switch)

Whatever its for sure there's no magic formula that will suit all. Think its more a case of knowing what the variable are then sucking and seeing which work best for a given rider and given conditions.

My work in analysing pacing strategies has shown that while there is a theoretical optimal pacing strategy using NP or TSS as a constraint on any given course and conditions, actual pacing strategies can diverge from that but still be very close to an optimal result (from a minimal time perspective).

Your observation about variability and length of course makes intuitive sense to me, given that in a 10 you are marginally supra threshold on average and so variability pacing strategies will, by their nature, force you into an element of go hard/recover mode, which is less likely for longer sub-threshold efforts since you may never actually go supra threshold at any time (and hence never actually accumulate any oxygen debt to repay).