Someone just pointed out to me that I forget to explain what "TSS" is in my post yesterday. Sorry about that. This gets rather hairy with further definitions needed, which I'm not going to get in to. Here it is...
TSS. Training Stress Score. In WKO+ software this is an indicator of how hard a workout is. The formula for TSS is:
TSS = [(s x NP x IF) / (FTP x 3,600)] x 100
where s is workout duration in seconds, NP is normalized power (or pace in running), IF is intensity factor, FTP is functional threshold power (or pace in running), and 3,600 is the number of seconds in an hour.
A cumulative, running average of workout TSS is expressed as CTL (usually a 42-day average). This is what I was referring to yesterday when speaking of the rate of increase in cumulative TSS as perhaps to be great for the rider who asked the question.
I hope that helped some, but I expect if you don't use a power meter, runner's GPS or WKO+ software then you have an even deeper level of confusion. The best way to understand this stuff is to train with such a device and use WKO+ to analyze your training.
Is there any sort of equivalent for those that train by HR?
Posted by: Krystyna | 06/28/2011 at 05:50 PM
Is WKO useful if I've not any PowerMeter but only a GPS ? (Forerunner 305 with cadence/speed option)
Posted by: Clement | 06/29/2011 at 11:19 AM
Clement--useful for running, yes.
Posted by: Joe Friel | 06/29/2011 at 01:15 PM
Krystyna--Yes, TrainingPeaks.com offers a HR version of what I described here.
Posted by: Joe Friel | 06/29/2011 at 01:18 PM
I use the WKO and understand how TSS fits in to TSB, CTL ATL, and the Performance Manager chart, but the unit analysis of the equation on which it is based has never made sense.
TSS =
[(sec) x (watts) x (watts / watts)]
-----------------------------------
(watts) x (seconds/hour)
= hours
So it is a really geeky, unathlete question, but shouldn't TSS be unitless? Like Intensity Factor?
Posted by: Madeleine | 06/29/2011 at 01:34 PM
Madeleine--I try not to worry about such things. :)
Posted by: Joe Friel | 06/29/2011 at 04:32 PM
Since IF = NP/FTP and since s/3600 = hours, the TSS formula simplifies as:
TSS = hours * (NP/FTP)^2* 100 = hours * IF^2 * 100
Posted by: Michael Schaefer | 06/30/2011 at 04:43 AM
I also started using WKO+ and TSS but my problem is that this formular is based on pace. I am orienteer, meaning I run a lot offtrail somewhere in the woods. there is also a lot of climb. The surface and the climb both reduce running pace which will reduce TSS. Is there a possibility or ways to get a TSS but based on duration and heart rate?
Posted by: Wolfgang | 07/01/2011 at 04:22 AM
Wolfgang--TSS in WKO is based on 'normalized' pace, which takes course gradients into account. It does not, however, account for trail conditions or wind. That said, if you use TrainingPeaks.com instead of WKO for your data download and analysis you can then use HR to determine TSS.
Posted by: Joe Friel | 07/01/2011 at 06:06 AM
ok, thx for the hint. I will give it a try!
Posted by: Wolfgang | 07/02/2011 at 05:48 AM
It is vital to be recording HR when you have a powermeter or a GPS watch for running? Will it give you better data for TSS/ CTL?
Posted by: chris | 07/03/2011 at 01:39 AM
Chris--No, HR is not necessary for TSS in WKO+.
Posted by: Joe Friel | 07/04/2011 at 11:39 AM
Just one for Madeline:
Technically/mathematically hours is the correct units but really its hours x [how hard you tried]. Essentially its a measure of the energy you burnt, or the effort you put in, in physics its called "work done".
The reason the units are confusing is we're dividing one power figure by another, implying that the units cancel out to a ratio, but the FTP figure can be regarded as a constant for a given athlete in a given period, so in that case the true units are hours x power which gives the correct units for work done in physics.
Its a very sensible (great) way of scoring a session although recently I decided it would be even more useful to track my TSS separately in each training or HR zone. So if my goals are building up base in the winter then seeing TSS for just my upper L1 to upper L2 figures seems more relevant to the adaptations I am trying to force at the time, rather than total TSS.
Joe I'd be interested in whether you agree with splitting up TSS into HR/power zones like this.
thanks
Paul
Posted by: Paul | 07/25/2011 at 02:30 AM
Paul--That's an interesting idea. I've never done that. Will need to think my way through it.
Posted by: Joe Friel | 07/25/2011 at 12:40 PM