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Thread: Zwift's ramp test is accurate

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    Default Zwift's ramp test is accurate

    To expand on the title...Zwift's ramp test is accurate for me.

    The set-up
    I have known for a couple of weeks that I was scheduled to have a stress test done today. This is related to an ongoing issue that is common for older endurance athletes - heart arrhythmia (SVT, AFIB, etc). Fortunately the doc that I see is runs a unit that specialized in athletes and has athletes come from all over the world to see him and his team. I just happen to live close enough to them.
    In other words, these guys know how to run tests to determine everything from VO2Max to wattage based thresholds, HR thresholds, O2 saturation, work at VT, etc, etc. A quick, fun, but painful test to find out those things while on a bike or treadmill.

    Because I have known that this test was coming up I did the Zwift FTP ramp/step test last week so that I could compare their results to one where I was connected to a bunch of devices measuring everything.

    The result
    1 watt difference for the measurement of wattage based threshold.
    As most of you know, that 1 watt is meaningless. Chalk it up to rounding error or lack of sleep or difference in hydration or different shoes...whatever.

    In other words, the Zwift FTP ramp test showed the same FTP as the throughly monitored test being conducted by an experienced professional who works with top athletes from all kinds of sports.

    Of course the full blown lab test was measuring all kinds of other things which is why I was there but I now feel confident that the Zwift test is providing solid information.

    Thoughts I would share my little experiment.
    Brian McLaughlin

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    Default Re: Zwift's ramp test is accurate

    A few questions:

    1. FTP strict definition is the highest average power one can sustain for an hour. How does your Dr + Zwift FTP compare to a 1 hour effort?
    I ask because my TR ramp test puts me at ~258w but my best all-time 1 hour effort is about 20w less than that.

    2. Were you using the same power meter in lab and at home?
    If not, what do you have on your Zwift bike and what was being used at the lab?

    3. I'm unfamiliar with the Zwift protocol. Can you post it? How was the lab protocol different?

    Thanks!
    elysian
    Tom Tolhurst

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    Default Re: Zwift's ramp test is accurate

    Thank you for sharing this info.
    This will be interesting to digest.
    Curious to examine it on my Zwift.
     

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    Default Re: Zwift's ramp test is accurate

    Quote Originally Posted by false_aesthetic View Post
    A few questions:

    1. FTP strict definition is the highest average power one can sustain for an hour. How does your Dr + Zwift FTP compare to a 1 hour effort?
    I ask because my TR ramp test puts me at ~258w but my best all-time 1 hour effort is about 20w less than that.

    2. Were you using the same power meter in lab and at home?
    If not, what do you have on your Zwift bike and what was being used at the lab?

    3. I'm unfamiliar with the Zwift protocol. Can you post it? How was the lab protocol different?

    Thanks!
    A few answers

    1. Not to get into a semantic debate...whether FTP's strict definition means the power you can maintain for an hour or not, the original intent behind this number was that it correlated nicely with a lab test to determine the various medically defined thresholds. Excuse the name dropping, but I happen to be part of a test and coaching group with Andy Coggan back in the day when we were trying to figure out the best way to train with power. I was but a minor stain on the wall of that era but I know there were a couple of others on this forum that were involved as well including Mr. TT.
    The only reason I bring that up is that I may not be using the 'FTP' correctly in this conversation as it is understood today. I am using (or mis-using) as we used it a long time ago.
    With that in mind, doing the lab test provides the wattage number that correlates to all the indices that are used to determine 'thresholds'.
    If there isn't already a thread about 1 hour efforts on flat vs up hill vs on a trainer vs hot days vs cold days etc etc I am sure there could be one.
    In other words...I don't have an answer about the difference in your TR ramp test numbers and an actual 1 hour effort. Other than 1 hour efforts are really hard not only physically but mentally. And if you did the 1 hour effort on a trainer...wow!!
    Back in the day we used to see high numbers outside than on trainers. But we also didn't have things like TR or Zwift or Kickers or the volume of data that these guys can collect.

    2. Good/important question. At home I have a Wahoo Kicker. The "power meter" is the Kicker and I am fairly lazy about doing the spin down test to reset it. In the lab the "power meter" is their bike. It is one of those multi-adjustable lab bikes to accommodate different sized people and it controls/changes/adjusts resistance and is calibrated often.

    3. You can find info about the test here. It is a basic step ramp protocol where the resistance increases every minute and you have to complete a minute at the new resistance (watts). You are done when you can not maintain the full minute at the new resistance. Thus the 'step' nature of the test. I did it in ergo mode in order keep one of the variables steady. In ergo mode you don't need to shift gears, as a matter of fact - shifting gears doesn't do any good because the trainer simply adjusts. Ergo mode kept my cadence 95-100 the entire time. If/when I do it again I will try it without the ergo mode on just to see what happens.
    The lab protocol is slightly different. You warm up for 10 minutes and then rather than 'steps' the lab bike steadily increases resistance 1 watt at a time at the rate of ~1 watt per second until you get over 300 watts then it starts increasing at 2 watts per second and as you go further into the 300 the increases per second go up more sharply. If you ever go below 60 rpms you are done. When you cannot go any more, you are done. It is a test to exhaustion. And once you hit that point you start soft pedaling or you can stop but you are still being monitored because at that point they are monitoring how you come down off that effort. I have had this test done a few times over the last 18 months and the worst part is that you have a mask over your nose and mouth which means when you are going really hard it is like breathing in a paper bag.
    Brian McLaughlin

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    Default Re: Zwift's ramp test is accurate

    That's great info! Thanks so much.
    elysian
    Tom Tolhurst

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    Default Re: Zwift's ramp test is accurate

    Just to take the piss out of the entire thread, screw FTP.

    Bear in mind that I have three bikes, all with powermeters. I am so far gone with powermeters that I have a used, sweat-corroded, no longer safe for any actual velodrome track bike with a flat front tire and yes, a powermeter, as my indoor rig. Powermeters are great for measuring work.

    All that said, screw FTP.

    I also have a history of some heart issues, and a pacemaker that German doctors implanted under circumstances that my US cardiologist says may or may not have merited an implant. I do train a good bit -- perhaps a bit too much for a 53-year-old, but I keep a cap on intensity.

    I keep coming back to heart rate. I know that my aerobic threshold is 123bpm. Now, my main concern is really just weight management -- I need to burn 1500+ calories each day to keep my weight down, because I have the appetite of a Labrador. If it's there, I'll eat it, simply because it tastes good. I can get those kj/calories in about 90 minutes of work right at my AeT. Most of the time, through, I just pedal at 115-120bpm until I get the work in for the day.

    As for hard, hard is hard. Just go hard for 1 or 5 or 20 minutes or whatever, even pace it, and the physiology will work itself out.

    If I want to know my FTP, I just go out and ride as even-paced hard as I can for an hour. Done.
    Robert Kendrick


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    Default Re: Zwift's ramp test is accurate

    Quote Originally Posted by DOOFUS View Post
    Just to take the piss out of the entire thread, screw FTP.

    Bear in mind that I have three bikes, all with powermeters. I am so far gone with powermeters that I have a used, sweat-corroded, no longer safe for any actual velodrome track bike with a flat front tire and yes, a powermeter, as my indoor rig. Powermeters are great for measuring work.

    All that said, screw FTP.

    I also have a history of some heart issues, and a pacemaker that German doctors implanted under circumstances that my US cardiologist says may or may not have merited an implant. I do train a good bit -- perhaps a bit too much for a 53-year-old, but I keep a cap on intensity.

    I keep coming back to heart rate. I know that my aerobic threshold is 123bpm. Now, my main concern is really just weight management -- I need to burn 1500+ calories each day to keep my weight down, because I have the appetite of a Labrador. If it's there, I'll eat it, simply because it tastes good. I can get those kj/calories in about 90 minutes of work right at my AeT. Most of the time, through, I just pedal at 115-120bpm until I get the work in for the day.

    As for hard, hard is hard. Just go hard for 1 or 5 or 20 minutes or whatever, even pace it, and the physiology will work itself out.

    If I want to know my FTP, I just go out and ride as even-paced hard as I can for an hour. Done.
    You know, there is really something to this. As a data geek I like to know stuff, and tried a Powercal HR strap and decided the data wasn't really reliable, then did a Powerpod for a couple of years and always was feeling I should tweak the parameter to get "better" data and would occasionally see readings that just didn't jive with PE. Still was intrigued so got a pair of Assioma Duos this summer for my new Alliance. I'm learning I have a pretty L-R discrepancy, which I supposed given the conditions of my knees and ongoing efforts to avoid TKR so that confirmed for me that the DUOs were a better option than single sided.

    At 65 with some occasional PSVT stuff that started in my 30s (yes, have done cardiac testing and nothing conclusive although my younger brother's had several ablations for AFib) I'm rethinking all this stuff. As a former nordic racer I think Seiler and co are bringing more visibility to things from years back; coupled with work by Friel and others on aging athletes I'm thinking HR/ventilatory response is good for Z1-2, and as Robert said above, hard should just be hard.

    Having said that, seeing some standardized metric improve is seductive for many of us, so I think the Duos will stay. Oh, and tangentially, I was concerned the change from SPD-SL to Look/Xpedo would be an issue. They work just find and I don't feel I'm giving up anything is stability etc. (Moved away from Speedplays about 7-8 years ago after riding them from pretty much the original introduction and haven't looked back.)
     

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    Default Re: Zwift's ramp test is accurate

    I think the zwift protocol has some issues, especially when it's run in erg mode. my stance is that the duration is too short so it lets you tap too much into neuromuscular and anerobic power to cheat the test. I have a couple teammates that have smashed the zwift test only to end up with training zones and workouts they can't complete. but what it does do is give you a field test that you can run efficiently within a training program.

    I think the hour is the only really accurate test but it's tough to incorporate that into real training since the physiological and psychological demands are so high. It's also tough to find enough road to really get it done unless you live next to some HC climbs or a velodrome.

    As a compromise I've mostly just done the 20 minute test. When I get closer to competition I'll just use numbers from a mid-week 2x20 workout or a normalized number from a crit to see roughly where my level is.
     

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    Default Re: Zwift's ramp test is accurate

    Quote Originally Posted by zachateseverything View Post
    I think the zwift protocol has some issues, especially when it's run in erg mode. my stance is that the duration is too short so it lets you tap too much into neuromuscular and anerobic power to cheat the test. I have a couple teammates that have smashed the zwift test only to end up with training zones and workouts they can't complete. but what it does do is give you a field test that you can run efficiently within a training program.

    I think the hour is the only really accurate test but it's tough to incorporate that into real training since the physiological and psychological demands are so high. It's also tough to find enough road to really get it done unless you live next to some HC climbs or a velodrome.

    As a compromise I've mostly just done the 20 minute test. When I get closer to competition I'll just use numbers from a mid-week 2x20 workout or a normalized number from a crit to see roughly where my level is.
    I think we might be talking about different things here. I also think we could create another thread dedicated to the value and/or use of using the results of the different test.
    But to stick to the topic of this thread....

    Everyone that has commented so far may know all of this but just in case others don't...
    Zwift is using a long standing test protocol and is not unique to Zwift. It is a standard ramp step protocol as described above. This test is generally done in a lab environment in which the subject is being monitored before, during and after the test. Generally the monitoring includes: heart signature (not just rate) via an EKG, oxygen intake, respiratory analysis (including the chemical make-up in each breath), blood pressure, and a bunch of other fun stuff. The results of the test show a number of indicators, how they track over time, how they intersect with each other, etc. Included in the results of these tests are indices of an individual's physiological thresholds.

    What I was surprised by was the accuracy of the Zwift results with a real lab's results. With a strong caveat to what @false_aesthetic called out in terms of what equipment was being used for the Zwift test that I did.

    All I am pointing out is the fact that Zwift has done some really good work in creating algorithms that align with real world lab tests without collecting all the other data that a lab test collects. I am not saying it is perfect. Just surprisingly good.

    BUT - how (or if) these numbers are used, whether someone can hold these numbers for prescribed training volumes, how different events require different usage of these numbers to get results, etc, etc are different topics than whether Zwift's ramp step tests is a level of accuracy close to real lab tests.

    Doing 20 or 60 minute sustained tests are providing different, but related, information. I will start another thread for that....
    Brian McLaughlin

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    Default Re: Zwift's ramp test is accurate

    Quote Originally Posted by Bewheels View Post
    I think we might be talking about different things here. I also think we could create another thread dedicated to the value and/or use of using the results of the different test.
    But to stick to the topic of this thread....

    Everyone that has commented so far may know all of this but just in case others don't...
    Zwift is using a long standing test protocol and is not unique to Zwift. It is a standard ramp step protocol as described above. This test is generally done in a lab environment in which the subject is being monitored before, during and after the test. Generally the monitoring includes: heart signature (not just rate) via an EKG, oxygen intake, respiratory analysis (including the chemical make-up in each breath), blood pressure, and a bunch of other fun stuff. The results of the test show a number of indicators, how they track over time, how they intersect with each other, etc. Included in the results of these tests are indices of an individual's physiological thresholds.

    What I was surprised by was the accuracy of the Zwift results with a real lab's results. With a strong caveat to what @false_aesthetic called out in terms of what equipment was being used for the Zwift test that I did.

    All I am pointing out is the fact that Zwift has done some really good work in creating algorithms that align with real world lab tests without collecting all the other data that a lab test collects. I am not saying it is perfect. Just surprisingly good.

    BUT - how (or if) these numbers are used, whether someone can hold these numbers for prescribed training volumes, how different events require different usage of these numbers to get results, etc, etc are different topics than whether Zwift's ramp step tests is a level of accuracy close to real lab tests.

    Doing 20 or 60 minute sustained tests are providing different, but related, information. I will start another thread for that....
    I'm just generally saying that ramp protocols are bad for establishing training zones, in my experience. If you want to narrow the discussion, fine. Here's my take:

    You don't have enough data points to really make a claim about how accurate the two procedures/setups are. You got the same result from two tests. That's not exactly enough to build a strong statistical relationship and most of the medical equipment from the lab test is just ancillary. Yeah, you can get a measurement of your true ventilatory and lactate thresholds but they're almost never really that different from a number you get from a simple power meter test.
     

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    Default Re: Zwift's ramp test is accurate

    We may be agreeing more than not. And the 'tone deafness' of the internet may be causing some interference.

    Quote Originally Posted by zachateseverything View Post
    I'm just generally saying that ramp protocols are bad for establishing training zones, in my experience. ...
    I am not claiming that a lab or a ramp test result directly correlate to a good training plan. As a matter of fact I don't think they do.



    Quote Originally Posted by zachateseverything View Post
    ...
    You don't have enough data points to really make a claim about how accurate the two procedures/setups are. You got the same result from two tests. That's not exactly enough to build a strong statistical relationship and most of the medical equipment from the lab test is just ancillary. ...
    Fair enough. This is a data point of one. I titled this thread stating something as fact that doesn't hold up under general scientific protocols. And perhaps my results are an anomaly. I am simply admiring the technology and am impressed that Zwift (or someone) has put in the time to create the needed math to take a test that is generally requires other data inputs to create wattage threshold without having those other data points.
    Brian McLaughlin

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