calculating FTP and Vo2 on EN 5.0

Brad Marcus

Bike test is tomorrow. Was just looking around to see how to calculate new FTP and Vo2 afterwards. Watched P's video on calculating new zones, but does that calculate my new FTP and Vo2 as well? Maybe I just am forgetting from my last test, are those numbers just what I average for power in my 5' and 20' tests?

My brain must be melting from all the sweat!

kens1964

Average watts for the five-minute effort is the VO2 max. 95% of your average watts for the 20 minute interval is the FTP.

Brad Marcus

Thanks Ken. Like I said - brain is fried today. Lotsa sleep tonight!

kevhill

Just to check are people using Average Power for the 5 and 20 minutes or Normalized Power - doesn't make much of a difference but wanted to check.

kens1964

It can make a difference to use NP versus AP. It depends on other factors (like whether you train on multiple courses inside and outside, and weather) But generally testing and training on a flat course or one with a steady grade on an indoor trainer like a CompuTrainer you can use AP.

John Withrow

I use whatever number is higher... On my trainer during tests, my AP is higher than NP. I posted a question about this a while back and was told it was because NP uses a rolling average, so it will be lagging for the beginning numbers. Doesn't really matter for a "test" per se... but for outdoor real world riding, NP is much more valuable.

Al Truscott

I use AP for 5 min, NP for 20.

Joe Matchette

Posted By John Withrow on 25 Feb 2013 07:51 AM


I use whatever number is higher... On my trainer during tests, my AP is higher than NP. I posted a question about this a while back and was told it was because NP uses a rolling average, so it will be lagging for the beginning numbers. Doesn't really matter for a "test" per se... but for outdoor real world riding, NP is much more valuable.

I see similar results.  For example, this morning's FTP test had the following for the 20' interval:

• NP 281
• AP 283
• VI 0.99

 Not that it makes that much of a difference -- 2W or 0.74%.  But, I feel like I earned the right to work harder, so I too am going to use the higher of the two.

kens1964

Here is the definition directly from Coggan:
TrainingPeaks uses a special algorithm to calculate an adjusted or normalized power for each ride or segment of a ride (longer than 30 seconds) that you analyze. This algorithm is somewhat complicated, but importantly it incorporates two key pieces of information: 1) the physiological responses to rapid changes in exercise intensity are not instantaneous, but follow a predictable time course, and 2) many critical physiological responses (e.g., glycogen utilization, lactate production, stress hormone levels) are curvilinearly, rather than linearly, related to exercise intensity, By taking these factors into account, normalized power provides a better measure of the true physiological demands of a given training session - in essence, it is an estimate of the power that you could have maintained for the same physiological "cost" if your power output had been perfectly constant (e.g., as on a stationary cycle ergometer), rather than variable.

This is also why NP and AP should be almost exactly the same on a flat course (or course with a constant elevation) with constant/reproducible environmental conditions (i.e., on your trainer inside at 70 degrees F).