What does this metric relate to?
If you’re familiar with CTL and how various levels correspond with an amount of training load that has been accumulated, Training Status looks to simplify the interpretation of Xert’s exponentially-weighted average daily work load for Strain to this concept. So rather than having to interpret or lookup what the meaning of a number between 1 and 450 would be, Training Status boils it down into 5 categories. We may decide to add your actual number as part of the tooltip that explains the stars. I think a better piece of information would be whether the number is increasing or decreasing, which is really what an athlete would be most interested in, I believe.
Yes, please! I’m trying to make the change from previously using WKO 3.0. Its been awhile, but my mind is still set with ATL, CTL, and TSB. Even being self-coached I could easily get how to read and manipulate those three for training improvements. So while I am just getting started again, I think it would be useful to have a bit more visual tracking, even historical tracking of Strain.
We are looking to provide a “next generation” PMC where we use Strain in place of the older stress score calculations. Total Strain/FTP*100 is actually a pretty good marker of training strain and based on initial testing, does appear to mostly agree with TSS. Fortunately, it doesn’t suffer from the inflation challenges associated with TSS. Let us know your thoughts on this and if anyone else is also interested, especially if they see it as a critical feature for them, do let us know.
Thanks. I wouldn’t mind knowing my Training Status number and what the values ascribed to the 5 categories are. This data could reserved for the Advanced page.
Why do you need to divide total strain by FTP? Isn’t total strain itself independent of what your FTP is anyway? Recently I’ve been copying Trainer Road workouts into the workout editor, noting their total strain, and then doing the ride outdoors. As outdoor riding is a bit more variable, I end up accumulating a bit more TSS, but return home with the strain equal. It does seem that strain alone is doing a great job at tracking existing TSS metrics.
@Rohan Ok. We’ll look at this further. @Oli Thanks for that feedback. Total strain is dependent on FTP as it defines the point where additional strain starts to accumulate. You are correct that the strain numbers go up with more work performed and down with less for everyone and varies with their signatures, but the impact of the strain will depend on FTP, at least this is how we’re seeing it. Hence, normalizing your strain wrt your FTP would make sense and hence is the current approach we are investigating. We’ll post some comparisons soon with some initial results once their ready.
Ah, I see what you’re saying - the fitter you are, the more strain you can handle. That said, that’s exactly what a PMC already does when we use TSS. An unfit person works at a lower TSS than a fitter person week-to-week. As they raise their fitness, they are raising the amount of TSS they are incurring. I’ll sit tight and see what you have to post later though 
The other important aspect to remember is that our calculation is based on strain, i.e. work performed. Stop pedaling and it stops accumulating. No way to get inflated values if you leave your Garmin running, for example. Alternatively, you can get much higher values if you dig real deep and stay there, i.e. bring MPA down and keep it there for a while. You’ll also see much higher values with hard 15s-15s or 20s-20s micro-interval workouts. These efforts get missed when you normalize power using 30s moving averages whereas, strain could actually be very high if they’re done with fatigue.
Stop pedaling and it stops accumulating.
This is what I really love about using strain, especially on longer outdoor rides. Getting stuck at traffic lights means I have to put in some more miles. Sounds good to me!
Thanks for the chart, that’s interesting.
Xert Strain Score (XSS) and Xert Equivalent Power (XEP) will be two new metrics that we’ll use in the development of our PMC capabilities. There are notable differences between XSS and the various other stress scores that rely on normalized averaging:
-
Stress score inflation - When averaging is used, if you’re idle, stress scores increase. Today if you make a long stop, or happen to leave your bike computer recording after your ride, your stress scores can be much higher than if you stopped recording. Often this is described as the “the burrito rule” if you’ve ever heard of that. The burrito rule means that if you’re going to stop longer than the time it takes to eat a burrito, your ride should be split into separate rides on order to prevent stress score inflation.
-
Stress score underestimations - If you are doing any training or riding where there are many surges in power that are less than 30s in duration, stress scores will be underestimated. For example, if your training is made up of 20s-20s micro-intervals, for example. This is because thes e measurements take a moving 30s second average which is then normalized. If you are doing a lot of these micro-intervals in your training, they can hide in your data and you may not be aware of the added strain your body is being put through.
-
Stress score overestimations from hard 30s-50s efforts - These are called “busters” and are especially prevalent during crits or other hard effort racing. For those with a large HIE component of their fitness, seeing normalized average power values that are well above your FTP for one hour is common and isn’t reflective of the actual strain your body experienced.
All-in-all, all these errors in calculation tend to cancel each other out but if you happen to do a bit more of one versus the other, your training load assessment may not be a true reflection of the load you have accumulated. This could lead to under-training if happen to do 1 and 3 more and undetected over-training if your training is made up of a lot of efforts as described in 2.
Our XSS and XEP metrics have addressed these errors in calculation and thus will not suffer from inflation or under/overestimates. Stay tuned…
I am game. I have both training peaks and Xert accounts. Mostly just using training peaks now to plan out my schedule because I’m currently doing running/swimming as well.