Questions on a) Hardness Test-workouts b) Real-Time MPA consideration by Xert

Hey guys,

First Question)
I have completed Hardness Test Level 09, so Level 10 is next.

From Level 10 on, there are two options, the normal Hardness Test or the respective “Alternative”.

The Alternative is described as the one to pick if my fitness signature does not allow me to complete the other one.

What in my fitness signature indicates that? I have ~270 FTP (3,8 W/kg), 1090 MPA, 22 KJ HIE.

Is my guess correct that the Alternative is more tailored towards the “Endurance” Phenotype like the Century Rider, TT, Sprint-TT and the original is tailored towards the High FRC-guys like Pursuiter, Puncheurs etc? Which Phenotype marks the border for Alternate and Normal Hardness test?

Second Question)
Xert advertises the SMART-designated workouts as adjusting “on the fly” depending on how the workout is going. I am using ERG-mode and I am also observing dynamic adaptions in certain workouts (for example “My way or the highway”) where the actual power targets in the workout deviate from the preview.

How does Xert know “how the workout is going”? It cannot be the power as I am in ERG mode. It cannot be my FRC as you cannot measure it. Remains cadence and HR as only variables. If not, what else is it? If so, how is it considered?

Open each workout in Workout Designer and note the difficulty and MPA drawdown graphs.
Watch this Academy session as to why and how an individual’s MMP is at play –
Episode D3 - Mastering Xert - Discover - Fitness Signatures and Conclusion - YouTube
Best from the beginning but I jumped to the example of cyclists with same TP but different physiology and the results when riding a SMART VO2max workout.
This lesson covers MPA specifically –
Episode D2 - Mastering Xert - Discover - MPA - YouTube

As you noted it’s your phenotype and power curve profile that makes the difference.
The Ranking tab on XO shows your profile as a spider graph. Someone with obvious strengths and weaknesses will have a pointy star-shaped graph while someone who’s strong all around will be just that – well rounded. :wink:

Youi want to be in AUTO mode on EBC when performing SMART workouts as some also include mixed mode (slope vs ERG control).
Many different interval types are possible based on your signature (XSSR) that affect both work and recovery intervals. Even warmup and cooldown can be smart intervals. The most noticeable type are dynamic duration and dynamic power. The former changes duration based on power output compared to the target while the latter changes power based on how well you maintain the target power.
[Many of the original SMART workouts had dynamic duration intervals which have since been changed to dynamic power as many users were alarmed by the fact the one-hour workout they picked didn’t end at one hour. :slight_smile: ]

As for the hardness tests, you work your way up the ladder and most likely fail at some point. If not, you are a pro level rider (5 stars status count) based on the hours you put in and a very tough one to boot.

Reference –
Introducing Smart Workouts – Xert (
Advanced Workout Design using SMART Intervals – Xert (

Even in erg mode your power is never exactly on target. It always takes some time to ramp up to power (while target goes up immediately) and power fluctuates above and below target even when steady. You will therefore see some adjustments with SMART workouts. That’s especially evident on workouts with short intervals like the one you reference. Cadence variations within an interval (eg as you ramp up) for higher intensity short intervals exacerbate this.

1 Like

Great question! SMART intervals (specifically Smart Power, Smart Duration, & XSSR) are based on your Maximum Power Available (MPA). The interval is designed to bring you to an exact level of fatigue (or recovery). As your actual power deviates from the planned intensity, these intervals will adapt second-by-second, updating the interval targets in real time!

As an aside, we don’t use FRC. It’s similar in concept to HIE, but HIE is calculated differently. We can calculate your HIE in real time, its just that we don’t care about the capacity of HIE in real-time. Instead, we care about how that capacity can translate into performance - this is Maximum Power Available (MPA).

Yes, I noticed that for the most SMART-Workouts, the target is drop my MPA to a specific value (which you can see in the preview). However, what you are saying about “actual” power and “planned” intensity derivation, does this work in “Auto”-mode? In my understanding, I cannot drop below the “planned intensity” in Auto-mode because as long as I keep cycling, the Trainer adjusts resistance so that I have to to deliver the power Xert is telling the trainer I have to deliver.

See for example an exert from a workout (it is now called “My Way or the highway 4.0”). If you look at The first 4/3 intervalls are flat. The last 7 are always somewhat “arbitrary”, but within the range. This cannot be due to fluctation, given the difference.

How is Xert adjusting that? Are heartrate and cadence input parameters to SMART workouts?

Looks to me like the power is not ‘exactly on target’ for either the work or recovery (you can add target power to the chart and see), which illustrates the point? It’s then dynamically adjusting so that you bring MPA to target…? Doesn’t take huge variations particularly for short intervals

If that is your post-workout chart it looks like you have a trainer with power smoothing enabled. You may want to disable that to see actual fluctuations generated during workouts.
May not address your question but you’ll get a more accurate representation of what occurs.

Related –
Focus duration seeming off - Support - Xert Community Forum (

I think the other reason may be the difference in type and duration –
4x30 sec @ 4 min MMP – flat (why does your chart show 3x in second set?)
1x1 min @ 75% PP MPA – flat
7x20 sec @ 75% PP MPA – not so much :slight_smile:

If you turn off ERG smoothing those 20 sec intervals will likely show if trainer response time is a factor. Since SMART intervals rely on actual power generated, I would think ERG smoothing would skew the in-ride calculation/adjustment. But does that mean better or worse?
In either case the difference appears minor, so you got the intended strain ratio work done. :+1:

It’s all about MPA. Xert is calculating second-by-second what your target power needs to be every second to end up at the target MPA value by the end of the interval. This really is apparent (not to mention helpful) for workouts that include near maximal efforts, such as sprints.

Check out this newer workout that features 5x 20s sprints in SLOPE mode, followed by 90s intervals that allow MPA to (mostly) replenish before the next sprint. If you overshoot or undershoot the sprint power targets, Xert will dynamically adjust the recovery intervals either way to ensure you’re ready for the next sprint. Pretty neat, isn’t it? :slight_smile:

Workout here: Xert - Login

1 Like

@ridgerider2 : the workout (My way or the highway 4.0) shown prescribes 4 reps before the “big effort” only in the first macrointervall.

Ah, now I understand why the 4x30/3x30 in the beginning are on spot. They relate to my 4 min MMP while the other relate to a certain fraction of my MPA being depleted.

What is ERG smoothing? Can I turn it of vai the Garmin Edge 530 during workout? But it leaves ERG in general enabled, right? The drops to zero occur from time to time, seems to lose connection 4-5 times per workout for a second or so. As for the strain, cannot complaint that the workout did not get the strain, that 60 seconds portion always kills me. The strain score shown after the workout also like the preview said.

@ManofSteele Ok, got you. So if there are sudden power or duration adjustments (rarely encountered the latter) it is always an adaption that might be to a power spike (or short connection loss) or something and that represents in my MPA deriving from what was predicted in the workout preview and therefore is adjusted “on the fly”.

If I have not touched the settings, is XERT in “Auto” mode and does “Auto” mode consider Slope portions of a workout or do I have to adjust it to slope mode? I think ridgerider2 indicated in his first post that the first is the case. Is Slope mode like the sections in Zwift that are “Free Ride”?

And one more question is open from my opening post: what determines which hardness test from level 10 I choose? Sure, ridgerider2 says I will fail somewhere on the ladder (and damn right he will be when looking at the workouts :wink: ) but what does it mean that “if you cannot do Level 11 given to my fitness signature, do Level 11 Alternative”. What in a riders fitness signature makes him fail Level 11 Hardness test but complete Level 11 Hardness test ALTERNATIVE, as both workouts show the same strain score and difficulty.

Smoothing is turned off within the trainer setup app –
ERG Mode Power Smoothing on Wahoo KICKR & KICKR SNAP Smart Trainers - YouTube

I have a Kickr Core - is that included by “Kickr”?

Yes. I believe the same app is used for all Wahoo trainers.

1 Like