Managing Power-Based Intervals in the 'Real World'

Aztec

I'm starting to do intervals based on power rather than HR now that my Powertap is up and running nicely.

So far, I find that on the road rather than the trainer, it's very hard (impossible, really) to keep on a target power level. I understand that I can work within a band (say if the target is 250w, I can try to stick with a normal distribution of power around 225-275w) and theoretically it'll work out to ~250w.

But... do you power trainers observe the current power on the PT or do you observe the average, so as to pick it up if the average falls and vice versa? Do you run long lags on the power reading in the first place? I currently have mine at 3 secs. Perhaps 15 would be better to smooth it out and make it more managable?

ric_stern/RST

obviously, due to the montonic nature of a trainer it's easier to maintain a specific power output on a trainer, however, we race in the real world where power will fluctuate with changes in environmental and topographical conditions.

i would therefore say that you should aim for a range, trying to keep it as high as possible within that range (and bearing in my your prescription for the session) and see where it ends up. my PT is set to display every 2-secs, but i record data at 1-sec intervals. i know my power will drop if the road falls away, and conversely will increase if the road tilts up a little, so manage my intervals by power and percieved exertion.

ric

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gooders

My powertap is arriving any day. Can you recomend any particular approach to power training? I've reading Joe Friels article on deriving lots of critical power zones through multiple testing. As I'm a triathlete I'm not sure I'll have time to undertake lots of repeat testing to derive good CP zones...which will no doubt change and need to be checked every 6-8 weeks.
Are there other simpler approaches? For example could you use you average 10m TT and 25mile TT average power for identifying training zones for interval work etc? I realise that power training is an exhaustive subject. I'm just looking for a simple approach to get me going and I'll look for something more comprehensive for the next season.

thanks

ric_stern/RST

i recommend two tests, a ~20-min TT/10-mile TT and a MAP test to derive your training zones, see: http://www.cyclingnews.com/fitness/?id=powerstern

If you're interested i can provide a testing service for you to derive these zones, tests and some other tests. we also offer a group testing session with a discount on testing for 5 or more riders.

please contact me further details
ric

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Smartt/RST

Current power vs. average power?: I've seen this question bantered around a lot, and it really comes down to personal preference as long as the desired result is achieved in the end. There are some issues to consider: current power is the most relective of your actual pedaling, but as you've noticed, it jumps around a lot; average power will smooth things out for you, but the longer you go into an interval, the less your current power output will effect the overall average due to the acculumation of data into the mathematical equation. As Ric alluded to, smoothing the display can help, but allways download at the 1sec interval if you want to learn as much as you can about the way you put power into the bike.
Either way, keep your eyes on the road more than on your power meter.

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Smartty