Mislabeled Intensity on Workout

Mount Regan is a TrainerRoad workout consisting of 4 x 8 minute intervals at FTP separated by six minute recoveries at 50% FTP. It is clearly a run-of-the-mill FTP workout, albeit with shorter than typical intervals. Here is the Xert chart for Mount Regan:

Now, Xert labels this as a difficult pure endurance ride. But not only is it not an endurance ride, my TrainerRoad FTP is 20 watts higher than my Xert TP so by Xert metrics these intervals are twenty watts north of TP.

Likewise, TrainerRoad FTP is about 10 watts higher than my Intervals.icu eFTP, so Intervals.icu actually considers this a polarized VO2 max session. Both TrainerRoad FTP and Intervals eFTP are automatically detected. Here is the Zone graph from intervals:

This is a hard workout. It’s not endurance paced. It is 32 minutes at FTP. I realize there is a lot of recovery here, but why does Xert consider this a “pure endurance ride” when it’s clearly polar and clearly not a base ride?

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Have a look at the focus duration of the workout. I think anything over 20 min focus is labeled endurance. But it’s just a label. The fact that it’s considered ‘difficult’ is what tells you that it wasn’t an easy endurance cruise

Re polar vs pure, if all the efforts are the same and around the overall ride focus duration, it’d be pure. Polar you’d need to be more significantly above the overall ride focus for your intervals. Eg. If you ended up with 30 min focus by doing a few intervals at 1 min focus duration power

You are correct. The focus is Sprint Time Trialist and the duration is 26 minutes. But the ride was literally 4 x 8 minutes at an intensity 25 watts above TP with 6 minutes rest between sets. How does it make sense to codify this workout as endurance?

I guess I’m unclear on what sprint time trialist means in terms of training effect. I thought the idea here was to do endurance efforts on yellow star days and punctuate them with harder efforts on green and blue star days in order to achieve a somewhat polarized distribution of intensity. But if this workout is considered endurance I must be misunderstanding because riding like this daily would be an absolutely terrible idea.

Here’s my Difficult Mixed “Endurance” workout from yesterday (SMART Song 2 Fixed) –


As compared to an Easy Pure Endurance workout a week ago –


When form is yellow (tired) that simply means no high intensity workouts will be recommended as with blue/green form. Endurance workouts include a range from easy to “hard” endurance with intervals into green (SS/Threshold territory). Some may tap TP or creep above it. However, the overall strain ratio classifies the workout within Xert’s endurance quadrant. IE, work performed below TP.

Sprint TT is the label for the 20:00 minute point along your power curve.

Keep in mind Xert is a set of guidelines to consider, not a rigid prescription. You always have a choice from a variety of workouts represented in both the top four list and Load More (top twenty). Or when you use Filter to change focus or the amount of time you have to train today.
IOW you can bend Xert to your will. If you only want lower-intensity endurance and prefer a more traditional polarized approach, you can do that. If you respond well to sweet spot, consider the “hard” endurance options which are easy to recognize by their thumbnail charts. Even so, most are not traditional SS sets of X minutes at X%. The few classic SS workouts are from the Coach folder versus the Xert curated Standard folder which contains a variety of SMART interval workouts. Once you realize all the benefits those run-of-the-mill FTP workouts will seem old-fashioned.

You can view any workout in Workout Designer beforehand to see details along with how your current signature applies to that workout. That may influence your decision as to whether hard endurance is a viable option for today.

Workout/ride classification depends on the profile math.
Rating: Easy, Moderate, Difficult, Tough, Hard
Specificity: Polar, Mixed, Pure
Focus Duration: 2 min (Road Sprinter), 3 (Pursuiter), 4 (Puncheur), 5 (Breakaway Specialist), 6 (Rouleur), 8 (GC Specialist), 10 (Climber), 20+ minutes (Endurance - Sprint TT thru Triathlete)

Reference –
Difficulty Rating – Xert (baronbiosys.com)
Specificity Rating – Xert (baronbiosys.com)
Focus Duration – Xert (baronbiosys.com)
Sweet Spot, Threshold and Polarized Training … By the Numbers – Xert (baronbiosys.com)

To better understand Focus Type/Duration I suggest you listen to the deep dive in podcast #21.
It is an important concept to understand and is a driving component in Xert.
Focus is also discussed in this Academy series video –
Episode I1 - Mastering Xert - Improve - Quantifying Your Training - YouTube

The strain for that focus is still overwhelmingly LOW XSS… You’re not really putting a large amount of strain on your HIE system.

HIE has most influence on your PD curve from 30s power to about 5 min power. Peak Power has most influence on your PD curve for <30s power. So, most everything beyond 20:00 (maybe even 10:00) is training your Threshold Power system.

VO2max intervals are performed best with efforts around your 4-6 min power (Puncheur, Breakaway Specialist, and Rouleur Focus Types). Look at workouts like Ronnestad (30-15’s) or Billats (30-30’s) - those both result in a much lower focus duration since the micro-rests allow you to spend more time at that higher intensity. Using our understanding of Xert, this is exactly why Ronnestad found the 3x { 13x (30s ON, 15s OFF) } provided superior training benefit over effort-matched 4x8’ intervals.

What I’m not sure, of, but suspect, is that if you are tired (yellow) XATA also suggests lower difficulty workouts, not just ‘endurance’. That would address your concerns as lower difficulty won’t have time above or even at TP. Someone with a higher training load will have to confirm though, as my TL has never been high enough to even be recommended those harder workouts

This make sense. I see how workouts at or near threshold are, strictly speaking, endurance workout in that they train the LIE system - i.e. threshold power. But then, there are a lot of different workout configurations that train the LIE system. Some of those configurations are sustainable day after day, while others (i.e. 4x10 at FTP) are not. If Xert codifies a threshold workout as endurance, presumably, it would suggest it as a daily prescription, wouldn’t it?