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CTL vs FTP

gingerflash1975gingerflash1975 Posts: 49
Hi
I'm new to power meters and have just read Joe Friel's book. He says that FTP testing should be done, ideally, about every four weeks, and power zones updated as FTP (hopefully) increases. that makes sense.
He also says that, ideally, one would see CTL continually rising, indicating improved fitness.
However, i am a little confused by this. CTL is based on TSS which is relative to FTP. The same work done will produce a higher TSS for a rider with a low FTP and vice versa.
I would therefore have thought that each time FTP is adjusted upwards, the TSS of an identical workout would be a little lower and therefore one would expect to see CTL rising for a period, then dropping each time FTP is adjusted, rising, then dropping etc.
Is that right?
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  • Read this:
    https://www.trainingpeaks.com/blog/the- ... e-manager/

    When you say an identical workout, you are referring to identical absolute power outputs. However one person's recovery ride is another person's threshold effort. Clearly each results in different "stress".

    The idea behind a training stress score is to provide a normalised indicator of training stress.

    So to normalise the stress score, rather than it being a function of absolute intensity, it's a function of relative intensity. In this case intensity expressed relative to threshold power.

    Likewise as an individual's fitness changes, so does the stress of any given absolute power output. IOW doing x minutes at y% of threshold results in the same stress score.

    In general to improve fitness you need to keep changing the stimulus. If fitness has improved but you are not also increasing the power and or volume to provide further stimulus, then your fitness will stagnate.

    CTL is reasonably correlated with fitness at low to moderate CTL levels. It's a way of quantifying "ride more" and "ride a bit harder at times" and fitness will improve. It gets a bit trickier as CTL gets higher though as the composition of your training increasingly matters. And of course you can't expect to always see CTL rise, eventually you need to recover.
  • bobmcstuffbobmcstuff Posts: 10,220
    What Alex says: workouts are normally done based on power zones i.e., % of FTP rather than absolute power output. So if your FTP changes the power zones also change. If two riders rode for an hour at 100% of their FTP they will both receive 100 TSS, regardless of their FTP relative to each other (one could have an FTP of 200 and one could have an FTP of 250, for example).

    When rides start seeming very easy or hard compared to what you expect for the TSS then you know a re-test is due...
  • Thank you. That was an interesting article you linked to.

    My point was that TSS, and therefore CTL, are relative to FTP.

    As FTP increases, then TSS for the same objective or absolute work done would be less. (a rider with a 400w FTP riding alongside someone with a 300w FTP would have a lower TSS for the same ride).

    So, if i do say 500TSS a week for a month, then find my FTP has gone up a little, then either same same workload (in absolute terms) would now generate a lower TSS, or more likely, I'll be riding faster for the same TSS.

    Put another way, if somehow my FTP moves from 300w to 400w, a 100TSS ride is going to be an awful lot faster, showing I'm a lot fitter, even though my TSS for that effort is just the same. If I did that 100TSS ride 5 times a week, my CTL would be no different than when i was at 300w, even though, at 400w I'm a hell of a lot stronger and fitter than before.

    I'm struggling to see how CTL shows fitness, if FTP is regularly tested and updated.
  • I'm struggling to see how CTL shows fitness, if FTP is regularly tested and updated.
    That's because it doesn't. At least not directly.

    What it does tells you is what your chronic levels of training stress or Chronic Training Load is (or has been in the past or will be based on performing a certain amount of training).

    It just so happens there is a reasonable correlation between improving fitness and an increase in CTL. Until there isn't.

    When I say reasonable correlation, I mean someone with a CTL of zero is definitely going to be less fit (e.g. have a lower threshold power) than when they have a CTL of 40, and they'll be fitter again with a CTL of 80. They might be fitter again with a CTL of 120, but for some that might also result in problems associated with extensive fatigue and performance may not necessarily be better.

    If you want to know your fitness, well you measure fitness for the task at hand. In cycling that's typically the power you can sustain over durations of relevance.

    Where CTL comes into the picture is as one means of monitoring how you are training. The idea is to provide sufficient stimulus required to induce positive physiological adaptations but not so much that undue fatigue results and performance declines.

    TSS, and the time based exponentially weighted averages of CTL and ATL and the difference between them - the stress balance - provide a way to quantify such things and by normalising the measures it means with reasonable care sound basic principles can be applied to training and for those with sufficient training history, be managed with some reasonable precision individualised for them.

    As with most things, it's a big picture guide to training (i.e. looking at the forest) but not the detail of what precisely you are doing such as the specific composition of training (which is looking at the trees).
  • I think the best way of looking at it is it's the patterns in the movement of CTL that can provide additional insight into your training and their potential impacts on performance.

    If FTP is kept reasonably current (i.e. doesn't say get a lot more than 10W out of alignment with reality), then the patterns of CTL with time can be a useful guide. Even if they are wrong it's still possible to interpret the trends if you are experienced enough.

    Things like the rate at which CTL can be increased that is enough for positive stimulus but not too much to create undue fatigue or avoid potential overtraining. How and how much to back off when leading into an important event. When training might be stagnating. What absolute levels you can reasonably manage given your individual situation and rest of life factors. What sort of absolute level you perform best at for a given event type. What sort of training pattern is optimal when the focus is on building basic aerobic condition. Or how to use the limited hours you have wisely.

    Typically there are limits and signs shown by these patterns. If your experience is not aligning with the typical pattern, then it's often a sign the FTP setting might be out.
  • FWIW, not everyone uses FTP or its derivative metrics.

    I use kilojoules (kJ) which is a measure of work. As I become more fit I need to increase intensity, duration or frequency in order to continually challenge the body. Increases in kJ reflect the improved fitness I needed to produce the increased work.

    Simple.

    If I wanted to know what my FTP is, and I don't, I could just use the power I'm able to produce on long intervals.

    Even if FTP wasn't already naturally available to me from my long intervals, I still wouldn't care as I target energy systems by performing intervals of different lengths at the maximum power I can sustain over all intervals.

    Simple.
  • bobmcstuffbobmcstuff Posts: 10,220
    FWIW, not everyone uses FTP or its derivative metrics.

    I use kilojoules (kJ) which is a measure of work. As I become more fit I need to increase intensity, duration or frequency in order to continually challenge the body. Increases in kJ reflect the improved fitness I needed to produce the increased work.

    Simple.

    If I wanted to know what my FTP is, and I don't, I could just use the power I'm able to produce on long intervals.

    Even if FTP wasn't already naturally available to me from my long intervals, I still wouldn't care as I target energy systems by performing intervals of different lengths at the maximum power I can sustain over all intervals.

    Simple.

    You may think that's clever, but it's just a different way of presenting exactly the same information.

    As FTP is a measure of the power you can sustain over one hour and kJ is a measure of work done (i.e., a combination of power and duration).

    So if my FTP is 250W, I could just as well say the maximum work I can do in an hour is 900 kJ as the two are literally identical.

    I can't see what benefit you think there is in using kJ, except that it is different to what everyone else uses.

    FWIW kJ is still useful, it is probably the best indicator of how many calories you've burnt, I like it when I get fitter and can burn more calories in the same amount of time as before and therefore eat more cake...
  • Remember the magic CTL number is 81, one this is achieved you can train harder, for longer and recovery quicker.
    I'm sorry you don't believe in miracles
  • wavefrontwavefront Posts: 242
    It's true, I just reached 81 CTL tonight, and Golden Cheetah now displays my CTL in green. Time to start training harder!








    :lol:
  • bobmcstuffbobmcstuff Posts: 10,220
    Only 71.

    Must be why I am so tired :(
  • I'm not talking about kJ per hour. I'm talking about kJ as an aggregate, such as total weekly kJ increasing over time.
    bobmcstuff wrote:
    You may think that's clever, but it's just a different way of presenting exactly the same information.

    As FTP is a measure of the power you can sustain over one hour and kJ is a measure of work done (i.e., a combination of power and duration).

    So if my FTP is 250W, I could just as well say the maximum work I can do in an hour is 900 kJ as the two are literally identical.

    I can't see what benefit you think there is in using kJ, except that it is different to what everyone else uses.

    FWIW kJ is still useful, it is probably the best indicator of how many calories you've burnt, I like it when I get fitter and can burn more calories in the same amount of time as before and therefore eat more cake...
  • bobmcstuffbobmcstuff Posts: 10,220
    I'm not talking about kJ per hour. I'm talking about kJ as an aggregate, such as total weekly kJ increasing over time.

    That doesn't tell you much about your fitness, all it says is you have done more riding this week. It could have been a week of junk miles.

    I thought your argument was that being able to do more work in a given time is a good indicator of improved fitness. This is just another way of expressing how much power you can put out over a certain period.
  • imposter2.0imposter2.0 Posts: 11,386
    bobmcstuff wrote:
    I'm not talking about kJ per hour. I'm talking about kJ as an aggregate, such as total weekly kJ increasing over time.

    That doesn't tell you much about your fitness, all it says is you have done more riding this week. It could have been a week of junk miles.

    I thought your argument was that being able to do more work in a given time is a good indicator of improved fitness. This is just another way of expressing how much power you can put out over a certain period.

    As above. It all seems a bit pointless using a 'performance' metric which doesn't directly relate to cycling performance, when there are already others (ie Watts, FTP, etc) which do.
  • Not sure what to you tell you. I become more fit ==> Increase load to challenge the body ==> I become more fit ==> Increase load to challenge the body ==> Etc

    Increased load = Increased volume or intensity = Increase intensity, duration or frequency = Increased power or time = Increased work = Increased kJ

    Here's my statement again:

    As I become more fit I need to increase intensity, duration or frequency in order to continually challenge the body. Increases in kJ reflect the improved fitness I needed to produce the increased work.
    bobmcstuff wrote:
    That doesn't tell you much about your fitness, all it says is you have done more riding this week. It could have been a week of junk miles.

    I thought your argument was that being able to do more work in a given time is a good indicator of improved fitness. This is just another way of expressing how much power you can put out over a certain period.
  • imposter2.0imposter2.0 Posts: 11,386
    Not sure what to you tell you. I become more fit ==> Increase load to challenge the body ==> I become more fit ==> Increase load to challenge the body ==> Etc

    You make it sound like a linear progression though - which it obviously isn't. Again, there does not seem to be any particular benefit in measuring KJ over watts or FTP, as the end results are the same, with the added benefit that watts will be a direct measurement of power (sustainable or otherwise) whereas KJ won't be.

    I've only ever seen one other forum member advocating kilojoules...
  • Typical AnalyticalTypical Analytical Posts: 165
    edited August 2018
    Again, no idea how to defend that increased fitness = increased fitness. I even said that I am increasing load to continually challenge the body because of increased fitness. The only other way I can say it is that if you are in a build phase and the top chart in the following visualization is not going up and to the right then you are in trouble.

    v8hd11v8q76ev9rzg.jpg?size_id=8
    Imposter wrote:
    You make it sound like a linear progression though - which it obviously isn't. Again, there does not seem to be any particular benefit in measuring KJ over watts or FTP, as the end results are the same, with the added benefit that watts will be a direct measurement of power (sustainable or otherwise) whereas KJ won't be.

    I've only ever seen one other forum member advocating kilojoules...
  • One of many benefits is that "greater fitness ==> more work ==> reflects greater fitness" is easier to understand than lectures on physiology and telling people to read articles with 7000+ words to understand the same thing.
    Imposter wrote:
    You make it sound like a linear progression though - which it obviously isn't. Again, there does not seem to be any particular benefit in measuring KJ over watts or FTP, as the end results are the same, with the added benefit that watts will be a direct measurement of power (sustainable or otherwise) whereas KJ won't be.

    I've only ever seen one other forum member advocating kilojoules...
  • imposter2.0imposter2.0 Posts: 11,386
    One of many benefits is that "greater fitness ==> more work ==> reflects greater fitness" is easier to understand than lectures on physiology and telling people to read articles with 7000+ words to understand the same thing.

    I don't think anyone is suggesting that people need to read 7,000w articles. Simply that perfectly acceptable 'conventional' definitions already exist for what you appear to be advocating. I can't help thinking you are simply trying to re-invent the wheel...
  • bobmcstuffbobmcstuff Posts: 10,220
    I guess the other advantage of TSS over kJ is TSS is relating to normalised power so has some relationship to how hard you went in the workout. Whereas kJ is a raw measure which doesn't make any account for training composition. Seems like rather a blunt measure of overall training quantity (but not necessarily quality) and I don't understand what advantage it has over say, weekly TSS (even though that as Alex has said isn't a perfect measure either).

    That chart above, apart from having hardly any labels, I'm struggling to see how it offers any benefit over the normal performance manager chart which is available on all training tools (including free Strava plugins like Stravistix), or made yourself in a spreadsheet (the formulas are very basic).
    Imposter wrote:

    I can't help thinking you are simply trying to re-invent the wheel...

    Either reinventing the wheel or being deliberately contrarian...
  • Imposter wrote:
    I don't think anyone is suggesting that people need to read 7,000w articles. Simply that perfectly acceptable 'conventional' definitions already exist for what you appear to be advocating. I can't help thinking you are simply trying to re-invent the wheel...

    This is the first sentence of Alex's first response:

    If that doesn't scare people away I don't know what will.

    Aside from that, suggesting a system to be conventional doesn't make it so.

    Don't get me wrong, I'd much rather people struggle to understand concepts like CTL vs blindly use generic plans based on a single number (which completely violates the principle of individualization) or silly automated coaches :roll:

    Heck, I even build tools that are completely compatible with FTP.

    But there's more than one way to skin a cat which is a phrase I use to see all the time in these forums and I don't know when the community lost that idea. Maybe it's all the money tied up in FTP. I don't know.
  • bobmcstuffbobmcstuff Posts: 10,220
    There's money in FTP??

    The main advantage of FTP is you can make power zones and train to it. You can't do that with kJ.
  • imposter2.0imposter2.0 Posts: 11,386
    Aside from that, suggesting a system to be conventional doesn't make it so.

    I said the definitions were 'conventional' - not the system itself.
    But there's more than one way to skin a cat which is a phrase I use to see all the time in these forums and I don't know when the community lost that idea.

    Nobody said there is only one way to train - indeed there are lots. But in terms of measurement, I'm still struggling to see what benefits - if any - your approach offers over referring to performance in the existing and generally-accepted ways.
  • Now we're getting somewhere. Great, constructive post. The devil is always in the details. Give me some rope with an extreme example just for illustration:

    Say I'm 100% aimlessly and randomly riding my bike outdoors with literally no criteria whatsoever. In fact, I even generate a random number on my PC regarding how long in duration my ride is.

    Then TSS is a godsend. How else would I have any idea what I've done and its training effect, etc.

    From the other extreme, let's say I'm doing a 90-minute fixed power aerobic threshold workout indoors under controlled conditions and the reason I'm doing 90 minutes is that my last aerobic threshold workout was 75 minutes and my decoupling dropped below 5%. Now I complete this 90 minute workout with a decoupling of 7% which is within the 5-10% rule of thumb so my next workout will also be 90 minutes until my decoupling drops below 5%. My plan is to continue following the 5-10% guideline until workout duration reaches the duration of my target event and decoupling is 5-7% ; after which I'm going to introduce higher intensity training, etc.

    I just typed all that very quickly so don't nitpick too much because the point is that there is something between

    (a) doing whatever and then analyzing and normalizing the daylights out of it

    and

    (b) super systematically progressing your training with extreme precision.

    In my estimation, as long as some deliberate and sound methodology for progression is used, then aggregating kJ at a weekly level to confirm things are moving up and to the right is all you need.
    bobmcstuff wrote:
    I guess the other advantage of TSS over kJ is TSS is relating to normalised power so has some relationship to how hard you went in the workout. Whereas kJ is a raw measure which doesn't make any account for training composition. Seems like rather a blunt measure of overall training quantity (but not necessarily quality) and I don't understand what advantage it has over say, weekly TSS (even though that as Alex has said isn't a perfect measure either).

    That chart above, apart from having hardly any labels, I'm struggling to see how it offers any benefit over the normal performance manager chart which is available on all training tools (including free Strava plugins like Stravistix), or made yourself in a spreadsheet (the formulas are very basic).
    Imposter wrote:

    I can't help thinking you are simply trying to re-invent the wheel...

    Either reinventing the wheel or being deliberately contrarian...
  • I'm not advocating training to kJ.
    bobmcstuff wrote:
    There's money in FTP??

    The main advantage of FTP is you can make power zones and train to it. You can't do that with kJ.
  • Imposter wrote:
    I said the definitions were 'conventional' - not the system itself.
    But there's more than one way to skin a cat which is a phrase I use to see all the time in these forums and I don't know when the community lost that idea.
    Nobody said there is only one way to train - indeed there are lots. But in terms of measurement, I'm still struggling to see what benefits - if any - your approach offers over referring to performance in the existing and generally-accepted ways.

    This is what I was responding to:
    Imposter wrote:
    I don't think anyone is suggesting that people need to read 7,000w articles. Simply that perfectly acceptable 'conventional' definitions already exist for what you appear to be advocating. I can't help thinking you are simply trying to re-invent the wheel...

    You can't say that there is more than one way to train as long as it's according to CTL :roll:
  • imposter2.0imposter2.0 Posts: 11,386

    You can't say that there is more than one way to train as long as it's according to CTL :roll:

    But I've never mentioned CTL in any of my posts. I simply don't see any advantage in using a less-relevant metric like KJ, when more-relevant metrics, like watts and FTP, already exist.
  • Watts and FTP don't show increased training load.
    Imposter wrote:

    You can't say that there is more than one way to train as long as it's according to CTL :roll:

    But I've never mentioned CTL in any of my posts. I simply don't see any advantage in using a less-relevant metric like KJ, when more-relevant metrics, like watts and FTP, already exist.
  • VamPVamP Posts: 674
    This thread should have stopped after Alex's second post. It's just gobbledygook now..
  • bobmcstuffbobmcstuff Posts: 10,220
    Watts and FTP don't show increased training load.
    Imposter wrote:

    You can't say that there is more than one way to train as long as it's according to CTL :roll:

    But I've never mentioned CTL in any of my posts. I simply don't see any advantage in using a less-relevant metric like KJ, when more-relevant metrics, like watts and FTP, already exist.
    TSS and CTL do.
  • ...aaaaand we're back where we started. I agree with Vamp. Let's cut this one off.
    bobmcstuff wrote:
    Watts and FTP don't show increased training load.
    Imposter wrote:

    You can't say that there is more than one way to train as long as it's according to CTL :roll:

    But I've never mentioned CTL in any of my posts. I simply don't see any advantage in using a less-relevant metric like KJ, when more-relevant metrics, like watts and FTP, already exist.
    TSS and CTL do.
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