FTP vs Lactate threshold

[flashd]

Hey guys,

Just wondering if anyone has any thoughts/experience on this.

I did a VO2max test back in December, right at the end of a strong CX season. The test was done on my bike using a Wahoo Kickr as the power meter. Lactate threshold was measured at 5.33W/kg, VO2max at 6.50W/kg.

After that test I took ~3 weeks off followed by a couple of weeks of unstructured riding then 3 weeks of more focused base training.

I did an FTP test yesterday as per Coggan's book. I performed this on my bike but this time using a Stages power meter (calibrated before the test) on a turbo trainer. My FTP came out at 3.98W/kg, which is ~75% of my LT.

I'm aware that lactate threshold and FTP are different measures, but I expected them to be much closer than that (I'd read on a forum somewhere that FTP~= 95% LT, but it can vary). Has anyone had both tested and noticed such a large difference?

Factors that may have contributed to the difference:
+ Tests were ~7weeks apart, so there's probably a genuine change in my power between sessions.
+ Test performed on different power meters, accuracy of calibration could cause error?
+ VO2 test was in a lab with a fan and people cheering me on. FTP test was on my own, on a trainer (outside), watching CX world champs.

The final question - which do I use for training? I'd been using my 95%LT to determine zones for training and it feels about right for Zone 2 base miles. But I've struggled to do repeated over-unders @110/90%LT so had a feeling that was a little too high, but I think that using the new FTP will feel way to easy. Should also mention that I've only started training with the power meter, so don't have any previous numbers to go off.

Any help much appreciated!

Cheers
Dave

[BikeAnon]

What was your HR during the LT test? How long was the LT test?

As for training, the simplistic answer is to use whichever test you can repeat. That's going to be the Coggan/Stages test.

Don't get hung up on the two different testing protocols, and how the results vary. Don't even get too hung up on the watt numbers you get on the Stages, versus other tools, or other people.


The key is repeatable FOR YOU. Even if the Stages reports your watts 30% incorrectly (unlikely), as long as it is consistent, you will be able to monitor changes, and use the numbers for power zones.


What software will you use to evaluate your training sessions?

[nathanong87]

if you just started using a PM, test often, and test a protocol where you can control the variables as much as you can. As bike anon said, too many things going on here to really get hung up on two different events that happened 2 months apart, taking time off the bike. And yes your fitness has likely decreased over that time also.

[flashd]

Thanks guys.

The VO2max test is a ramped protocol and you approximate LT via gas analysis (not actually measuring lactate levels). Started at 100W and increased by 35W each minute until failure.

Heart rate at LT in test 1 was 178, average HR in test 2 was 182. Interestingly, when I've tested for FTPhr before (30 min flat out, average HR for last 20 min) my HR was 188bpm, but that was outside so adds another level of complexity. I'm using GoldenCheetah for analysis.

Yeh I'm sure I'll learn a lot more about it (and myself) the more I use it. @Nathanong, how often is often? I'm planning on testing every~4 weeks. Do you think it'd be worth while testing more frequently at the beginning to get a better estimate on the numbers?

[nathanong87]

rest and test, test every 4 weeks is fine. All im saying is the more data you have, the more you know how to pace, the better.

[boots2000]

The VO2 max test that you did yielded pretty useless information.
At least not applicable in the real world to training zones.
A 35 watt increase every minute allows you to reach a power level that you could never get to with more moderate increases.
I would go with your Coggin test data- update every once in a while.

Thanks guys.

The VO2max test is a ramped protocol and you approximate LT via gas analysis (not actually measuring lactate levels). Started at 100W and increased by 35W each minute until failure.

Heart rate at LT in test 1 was 178, average HR in test 2 was 182. Interestingly, when I've tested for FTPhr before (30 min flat out, average HR for last 20 min) my HR was 188bpm, but that was outside so adds another level of complexity. I'm using GoldenCheetah for analysis.

Yeh I'm sure I'll learn a lot more about it (and myself) the more I use it. @Nathanong, how often is often? I'm planning on testing every~4 weeks. Do you think it'd be worth while testing more frequently at the beginning to get a better estimate on the numbers?

[jekyll man]

FWIW It's pretty well documented about kickr's overreading by about 30w esp if they arent recalibrated after warm up.
On the other hand (or crankarm), you're using a random number generator which could be churning out anything.

Take your pick as to which is right

Its also dangerous to assume that percentages are exact; 95% could be 1 person, and for another 88?


As others have said, if the majority of your training is done on the turbo, base any zones on what you can achieve on that.
If its on the road, stick to what you can do outside.
For a lot of people they cannot hit anywhere near the numbers they do outside, when on the turb. Just accept it/work on closing the gap).

And pick a decent repeatable testing protocol, or use race data

[acoggan]

The first test determined your ventilatory threshold (VT), not your lactate threshold. Depending a bit on the exact criteria used to define VT, it should be essentially the same as FTP, at least on average. You should seriously question the credentials/understanding of anyone who claims otherwise.

[LouisN]

Any professional to the sport would be welcomed to add such a "title" to his(her) profile.

Louis

[spdntrxi]

No way is my kickr over by 30w .
I've read the stories but for me.. Nope and I hardly ever zero mine out


Sent from my iPhone using Tapatalk

[KWalker]

Sign up for Xert beta. It can accurately predict MMP values down to the minute once it learns your rider signature. Amazing stuff. Uses a very robust model and ML algorithm to estimate various physio parameters and their contribution to the rider's signature.

You can also use the 3 parameter or 2 parameter model in GC, both of which I've found to be more useful than the 20min 95% Coggan test, which often overestimates FTP esp i lesser experienced/lower fitnessed riders.

[Ghost234]

A drop like that over 7 weeks is alot....


I have a Kickr and it has sometimes given some high values. I particularly remember a few rides that had the power read about 15-20w higher than my PM.

I would use the stages result personally. The Kickr can read a little high.

[baronbiosys]

Sign up for Xert beta. It can accurately predict MMP values down to the minute once it learns your rider signature. Amazing stuff. Uses a very robust model and ML algorithm to estimate various physio parameters and their contribution to the rider's signature.

You can also use the 3 parameter or 2 parameter model in GC, both of which I've found to be more useful than the 20min 95% Coggan test, which often overestimates FTP esp i lesser experienced/lower fitnessed riders.

Thanks @KWalker

Xert can determine your threshold power from regular ride data. Many of our users simply upload rides or races where they knew they had pushed themselves and Xert can extract your fitness data (i.e. FTP) from the ride data.

Since you're looking to establish a threshold to determine training targets, check out our blogs/videos on workout design and you'll see how a *one size fits all* %FTP-based targets often don't work the way they were intended.

Xert is free during the beta period.

[jlaitinen]

How realistic is the FTP-value that Xert calculates from the training data? Just curious as I have not done a 20minute test in a while and the value that xert has calculated is quite high.

[helldiver]

Very interesting stuff (Xert), i will research the algorithms used, as I'm curious how could the models calculate 305W threshold power for me, seems way to high. Last time i tried to test FTP was a 20min test couple of days ago when i got my powermeter, i started riding at 250W (because that was what i assumed my FTP would be), at the end of the test (last 1-2minutes) i realized i could do better and i managed to hold little more then 300W till the very end.