Apologies, I just re-read my post and it looks short&snappy (I was in a work meeting 
)
Yes Iām Xert user and Iām happy to vouch for them, but you are also free to criticise Xert! 
No problem. Iām an Xert user as well as TR
I ignore Garmin. Too many limitations including the fact that it only accounts for activities recorded on a Garmin device (I.e. Ignores TR workouts even though theyāre synced to Garmin Connect) and puts too much weight on a VO2 estimate which I donāt trust anyway.
When the weather is great and I do all my training outside it thinks Iām overtraining. When itās wet and windy and I do all my training on TR or Zwift it thinks Iām recovering. And right now Garmin thinks Iām āOverreachingā because for some reason it decided to unilaterally change my FTP from 340 to 220 (I normally set FTP manually based on TR ramp test and I swear I didnāt touch the settings), I then did a 4 hour ride at NP 260 which of course it thinks is about 600TSS. Even when 100% of my training is recorded on Garmin and my FTP is set correctly my training can pivot instantaneously from āProductiveā to āUnproductiveā and back again based on a 1 point change in my estimated VO2 Max which is as likely to be down to heat, nutrition or hydration as it is to fitness.
Tried Xert a year ago and it seemed to correlate much better with how I was actually feeling. Would still only use it as a sense check though, not the main determinant of how I trained.
Honestly Garmin training status is garbage (I have a forerunner 945). Itās way too tied int the VO2 max/performance condition estimate, thatās why it will only take into account activities done on garmin. It sets VO2 est based on your perf condition est that it gives you while you are actually doing the activity using the first beat stuff - it canāt do firstbeat after the fact.
If you donāt do VO2 type workouts then your VO2 est will just plummet.
Itās told me I am detraining the same week Iāve hit a new PR in a ramp test and I know by the workouts I have been completing that I am the fittest Iāve ever been.
I could rant about it all day.
2 Likes
Thats my point-of-view after using it for over 18 months on a Garmin 530 bike computer with a Garmin premium chest strap.
The advanced metrics from Firstbeat have been fine, hit or miss on some things but trends are accurate. I mostly use it to cross reference against other stuff (metrics and feelings). My favorite feature is post-workout looking at Performance Condition (which uses HRV), its pretty common to feel just okay at the start of a workout, see a low score, and then do a hard set of intervals where I feel stronger and stronger and the HRV based Performance Condition will increase (and the opposite if I start out feeling good, then struggle with hard intervals).
Not sure about the advanced metrics, but FirstBeatās (running) Race Predictor is a famous piece of garbage, posting ridiculous race times (currently a 36-minute 10k in my case, whereas the best I could hope for would be 40ā; those who run realize what a long way it is from 40ā to 36ā).
I wouldnāt trust anything based on this companyās formulas, or anything Garmin tells you, given the fact that the Race Predictor has been like that forever and the only people that care are the disillusioned users.
N=1, Garmin has seemed to match pretty close to how I feel. I do everything on my Garmin though, so everything is tracked.
But I let how I feel determine everything I do. I never let an algorithm tell me how I feel.
2 Likes
Could very well be a bug in the planner display for you. Calculating and updating all the training status for each day involves a lot of computation that has to be done correctly, both on the server and on the browser so if something doesnāt seem right, donāt hesistate to contact support. Some accounts need a tweak, often from miscalculations that were made in previous versions of the software or from errors in data. Weāre usually pretty responsive for this reason.
1 Like
May help with some of the comments made here:
1 Like
i donāt think garmin is really a random number generatorāit clearly picks up and tracks the heart rate: power relationship over timeābut whether that = reliable estimate of your vo2max is an entirely different question.
Like iāve read the white paper but i also regularly see changes in my HR response to power, especially in the short to medium term, that i wouldnāt expect to have anything at all to do with Vo2max.
I suspect the Garmin vo2max estimate is at best somewhat like using 220-age to get max hr, plus can be influenced by short term factors affecting HR that confound the results.
But i guess bottom line to the OP, either or both of the systems could be inaccurate here, but both also have their uses (as you know), you just have to be aware of their limitations.