So, what am I doing wrong here?

I achieved a breakthrough the other day. Hooray and all that, but the result of the breakthrough was a 60 watt jump in my PP and a 3 watt jump in my TP. My new PP bears zero resemblance to the power I can actually produce. I don’t think I have EVER, even for one nano-second, been within 100 watts of it. My TP on the other hand, between decay and lots of endurance workouts during base phase, is at least 35 watts below what a ramp test would give as FTP. We aren’t talking big numbers here. I’m an enthusiast closer to 60 years old than 50. On the breakthrough, it took a series of rollers to bring down MPA enough to have a fighting chance of producing a powerful enough sprint to breakthrough. Now, at 60 higher PP I’d be pretty gassed by the time I could even attempt to breakthrough. Am I approaching this the wrong way?

Your PP can be higher than you’ve achieved if you achieved it while fatigued, which it sounds like you did. You can do more when fresh.

Regarding fitness signature And breakthroughs, I can recommend listening to episode 18 of the Xert breakthrough lab podcast (actually worth listening to all from the beginning)

You don’t actually need to sprint to breakthrough and in fact it’s better (more accurate signature extraction) to bring MPA down to TP first (by riding above TP for a while, whatever intensity you like or fits the terrain… continuously or not, just bring MPA down) and then maintain a high effort as long as you can


Thank you for the helpful advice!

Good response @wescaine , I second the recommendation on the podcast (and indeed all of them). I found that one particularly helpful and it gave me some new insights. I intend listening again when I am not training and taking some notes.

No probs - curious to see how you get on with your next BT ride

Did you do any type of BT workouts to arrive at your starting signature or did you simply load historical data and set a TED?
Are you strictly accepting suggested workouts or mixing things up during phases?
You mention performing a RAMP test in the past. How long ago was that?
Do you ride outdoors only or also indoors on a trainer?

If you feel your signature is off you can contact and ask them to review your data. Or you can edit the numbers yourself under Account Settings, Profile (don’t recalculate) and see what changes occur on subsequent workouts.

I also suggest you listen to podcast #17 that discusses efforts required to establish your signature, plus how to locate invalid data using the activity table and flag or fix it, and advanced options like refresh, extract, and save/lock when viewing an activity.

Hi Steve,

Good questions. Like others have recommended, check out the podcast series. We’ve tried really hard to elaborate more on how the system works, and to explain why the system gives the results that it does.

Without getting too deep into the nitty gritty, if you push for a hard sprint under fatigue, you might very well see an increase in PP. The assumption that the system is making is that if you could do that sprint effort under fatigue, then your starting Peak Power has to be higher than currently recorded in the system. Personally, I’ve never really hit my Peak Power, as hitting it will require almost the perfect scenario of inertia, resistance, and cadence/gearing. Unlike other systems, we don’t display your Power Duration curve as what you have done, but rather what you could do on a good day. Hitting your numbers below ~1 min on the power duration curve will require near perfect execution and a good cadence selection (being at a non-optimal cadence increases fatigue more quickly than being at the ideal cadence - think about trying to do a 1 min effort at 40rpm vs at 100 rpm).

Re: TP, the best way to get a valid reading for TP is to have an effort near MPA for extended periods of time. I typically find a micro-interval workout good for this (such as the Ronnestad workout (30/15’s), tabatas (20/10’s) or billats (30/30’s)). They allow you to sufficiently draw down MPA and keep it suppressed for extended periods of time, which makes for a good way to tease apart your signature - in particular HIE and TP.


wescaine, I haven’t had a chance to listen to the podcast yet, but I tried to implement some of your advice. The BT I mentioned above lasted only 8 seconds. My PP was 482 and I got my MPA down to 323 before I sprinted. Part of this was a function of terrain. Using your advice, I was able to achieve another BT a few days later. PP was now 562 and I got MPA down to 315 in a much more patient fashion. I was able to hold my effort above MPA for 36 seconds. I’m doing these attempts in Central Park (NYC). It is a 6 mile rolling loop. If you use Zwift you are probably familiar with it. One challenge is there are some significant downhills that make it hard to keep power over TP and MPA drifts back up. It leaves you with a feeling of needing to “go now, this is your last chance”. In the future, I will try to minimize the updrift in MPA because after the descent is a series of four rolling hills that could allow me to bring MPA down even closer to TP . Thanks again.

ridgerider2, I just allowed Xert to upload my Strava data. I thought that data was pretty clean, but not a lot of BT efforts in it. Since I’m not a racer, I figured I could just be patient and let the FS adjust itself over time. When on a trainer, I usually accept suggested workouts or something similar. When riding outside, I find this hard to do. I live in a crowded place without a wide variety of nearby choices. Instead, I try to match XSS with Xert’s suggestions and match intensity to some extent. For example, 3 laps around Central Park can be 95 XSS or 210 XSS depending on effort.

I’m not sure about my FS, but I can’t complain about Xert. I find it motivating. My TL is trending upward nicely. My second BT ride allowed me to complete a lap of the park in under 20 minutes for the first time ever. Even when I was much younger with no kids I wasn’t able to do that. Also, when I do an easier ride and compare with previous laps of the same time, my average HR is over 20 bpm lower for the exact same terrain.

Scott, Thanks. See my other replies for my praise of Xert. A podcast for how simple enthusiasts can best use Xert would be great. There are a lot of us out here.

I don’t use Zwift much but think you can connect your trainer just as a powermeter, and not let Zwift control your trainer? Then you can ride whatever intensity you want for as long as you want without feeling the up or down hill sections. Depending on the trainer you can then ride free ride or even connect your trainer to Xert to run workouts (and do them in slope mode / without ERG mode for BT efforts) while riding in Zwift.

That’s not the issue. I mentioned Zwift just in case you were familiar with the rolling nature of the park from the virtual world. My BT efforts were in the real Central Park, as I live two blocks from there. The issue is keeping my power high enough on a 7% downhill grade to prevent the MPA from drifting back up again. If I can figure out how to do that, I can be more patient about bringing down my MPA and getting a better BT (and better FS).

Take a look at Workouts, search for “breakthrough”, and try the 31 minute one next time you get a chance to ride on your trainer (not outdoors).
If it’s a smart trainer and you are using the mobile app you can leave it set to the new Auto Mode. Otherwise run in resistance or slope mode which will require you to switch gears and cadence to meet target watts (same as riding the workout on a dumb trainer).
In Auto mode on a smart trainer you can just let the smart trainer do it’s thing.
If you finish the workout in Auto mode and think “that wasn’t so bad” then your signature is off. :slight_smile:
If you find the 31 minute BT workout too taxing, try the 46 minute version next time (a couple weeks later) as the interval placements differ so you may like it better. In either case you’ll get an idea the type of efforts/focus required to establish an accurate FS.
Once you have that dialed in just continue following the XATA suggestions but don’t be afraid to mix things up when you feel like it and take rest days.
You can also search for “ramp” and perform that type of test but RAMP tests are one-dimensional in focus and don’t fully test your signature values.

Ok, misunderstood!

Only other idea is to ride with brakes on down the hill to add resistance, but not sure that’s safe or easy when you are gasping for air on the verge of a BT, and will look a bit odd…!

Over the last several weeks, I’ve been able to achieve a few breakthroughs by more patiently bringing MPA (according to my Garmin) down to TP and then maintaining effort over TP but only going all out after several minutes of time above TP. Wescaine, your advice has been very helpful and the recalculated FS seems to be moving towards what I’d expect. Two follow up questions.

  1. The XSS using the Garmin app was 440 at the end of the ride, but once processed by Xert was only in the 280’s. Is that a result of using the updated signature?

  2. Once the MPA was drawn all the way down to TP, it effectively froze there on the Garmin. It didn’t go lower when I continued at an above TP pace, and when I eased up it didn’t really drift back up either until I made a full stop for caffeine and a biscotti. Is that to be expected on the Garmin before the updated FS is used?

Thanks for your thoughts.

  1. Yes. You can use advanced MPA when analyzing the activity to see how it looks with old and new signature. With the old one it thinks you’re doing a superhuman ride by riding for minutes above MPA, but when the signature is refreshed you see you weren’t (by definition)

  2. Yes re hitting the floor of TP but not sure on the recovery thereafter… maybe someone else has a view there…?

By definition, MPA cannot go any lower than TP (since TP represents the maximal aerobic power output - you can always ride at TP, in theory). The recovery takes a while longer because MPA was suppressed for so long.