Training Load

by mechgt

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Time constants for ATL and CTL

Time constants for ATL and CTL

Postby RiverWinz » Sun May 30, 2010 1:58 pm

I was wondering what you think are reasonable time constants for ATL and CTL. So far I have been using the default values (11 and 45 respectively) but thought that especially ATL did not describe reality.

Using 11 for ATL means that it will take ~31 days to get to 5% of whatever level your at (e.g 100 -> 5). 31 days for full recovery seems a very long time to me. Setting it to 5 leads to ~13 days to get to 5%, which to me sounds more reasonable. What do you think?

Using 45 for CTL means that whatever shape your in is down to 5% after ~133 days. Is this reasonable?
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Postby ildibad » Mon May 31, 2010 9:58 am

I think that you are caught by some border effect of the math ...

CTL on a span of 45 days means just that the influence of the training older than 45 days is equal to 0.
ATl on a span of 11 days means that you need at 11 days to recover fully from fatigue.
I feel that these values are fairly consistant with my personnal feelings.

When looking at the graph, I'm more interested by the trends and the shape than from any particular values.

Remeber that training should decrease both CTL and ATL on the long run. the same amount of kilometers at the same speed should be easier.

So my advice is to avoid giving to much weight to the figures.
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Postby racerfern » Mon May 31, 2010 5:52 pm

ildibad wrote:Remeber that training should decrease both CTL and ATL on the long run. the same amount of kilometers at the same speed should be easier.

So my advice is to avoid giving to much weight to the figures.


Agreed, however your CTL and ATL will not decrease with equal training unless you re-test and establish a new higher FTP, I believe. Assuming you raise your FTP then you will have to increase your duration, intensity or both to achieve the same training effect.

That said, I don't even track ATL. My CTL is very slowly climbing and if I get to 100 I'll be surprised. Of course at that point, I'll need to do a field test which should bring my CTL back in line.
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Postby mechgt » Tue Jun 01, 2010 9:06 am

ildibad wrote:CTL on a span of 45 days means just that the influence of the training older than 45 days is equal to 0.
ATl on a span of 11 days means that you need at 11 days to recover fully from fatigue.


These statements are not entirely accurate. OP has the right idea on the math portion of it. These (CTL & ATL) are decaying values, and mathematically all past trainings will impact your CTL/ATL. The effect of really old activities is in fact very negligible, but it's not quite 0, just to be accurate.

Anyway, 5% sounds like a very arbitrary number to calibrate against. Any reason for this choice? (Not trying to pick, I'm always open to hearing new ideas :) )

The default numbers (11 & 45 days) were chosen based on Eric Bannister's (and others) TRIMP research, and specifically were found in one of the technical research papers listed here ("Modeling human performance in running"
I believe):
Training Load Introduction

Note that technically everyone's constants are different, but in reality this (Training Load) is a mathematical model, not the law. You might tune it, but as Ildibad said, I wouldn't get too wrapped up in trying to make it "exactly right" (as I don't believe that exists). It uses a mathematical algorithm to model or guess, what we experience, it's not a precise measurement.
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Postby Ruskie » Fri Oct 08, 2010 5:39 am

mechgt wrote:
Note that technically everyone's constants are different, but in reality this (Training Load) is a mathematical model, not the law. You might tune it, but as Ildibad said, I wouldn't get too wrapped up in trying to make it "exactly right" (as I don't believe that exists). It uses a mathematical algorithm to model or guess, what we experience, it's not a precise measurement.


And btw, what are we supposed to put as "Initial" ATL and CTL, and/or how to estimate those initial values?
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Postby racerfern » Fri Oct 08, 2010 6:29 am

I use 42 for CTL and 7 for ATL. Some people use 11 for ATL.
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Postby Ruskie » Fri Oct 08, 2010 7:56 am

Yep, those are the values for the constants (I use 11 too, for running). But there are two other values, by default at 0, which are ATL and CTL "initial values". I wonder what they are for and how to estimate them...

Thanks
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Postby texmurphy » Fri Oct 08, 2010 8:16 am

Ruskie wrote:But there are two other values, by default at 0, which are ATL and CTL "initial values". I wonder what they are for and how to estimate them...

They are used to extend your moving averages back before your history. Assuming you have been in training prior to ST recording, then they would be your estimate of that training. If no change in training then use your current values. Or if the ST usage start was well into the past, leave it a 0.
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Postby Ruskie » Fri Oct 08, 2010 8:23 am

texmurphy wrote:
Ruskie wrote:But there are two other values, by default at 0, which are ATL and CTL "initial values". I wonder what they are for and how to estimate them...

They are used to extend your moving averages back before your history. Assuming you have been in training prior to ST recording, then they would be your estimate of that training. If no change in training then use your current values. Or if the ST usage start was well into the past, leave it a 0.


Oh! Then they are like p0 in the trimp formula... well I have data starting early last year, I do not think those constants may make a big difference then... ;)

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Postby ksherman » Sat Oct 09, 2010 2:25 am

It seems to me that there are two ways to look at the CTL. As a resource to be run down, or as a fund to be built up. Given that generally we are not in the game of de-training I tend to the latter. And John Hellemans who is an outstanding NZ triathlete coach always worked on the basis that meaningful fitness changes took 8 weeks, so based on that if you are trying to assess the value of your current training load I would be tempted to go out to 56 days.
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Re: Time constants for ATL and CTL

Postby vaajin » Thu Nov 17, 2011 12:05 pm

I think this has especially to do with the math border effect. However, I do not think that the value of CTL and ATL holds true forever as it is subjected to change. And since they are decaying values, equaling zero is for the most part impossible.
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Re: Time constants for ATL and CTL

Postby sunbeam » Sat Dec 17, 2011 11:18 am

Hi,

I've been collecting experience with Training Load for a few months now. It's very interesting to see how various workouts add up differently.
Right now, I'm trying to be conservative and regard CTL as a better parameter to describe and add up my training efforts than "weekly mileage". I think it primarily does just that.

A few points, though.
I'm 48 years old and wonder whether there are any data or experience how age affects the ATL and CTL time constants. Clearly, I'm not recovering as fast as I did when I was 22...
It may also take me more time to "build up" CTL.
I'm using 12 and 45 right now.

Second, I have the feeling that when I do really hard intervals, like 5 x 1 km way below my current 10k race speed in anaerobic territory and reaching up to 95% of my heart rate reserve, it does give me relatively few TRIMP points - compared to let's say a relatively easy run at constant speed and maybe at 69% of heart rate reserve (that would be around 77% of maximal heart rate).

Do you have the same observations?

Thank you,

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Re: Time constants for ATL and CTL

Postby the5krunner » Sat Dec 17, 2011 12:13 pm

sunbeam wrote:Hi,

I'm 48 years old and wonder whether there are any data or experience how age affects the ATL and CTL time constants. Clearly, I'm not recovering as fast as I did when I was 22...
It may also take me more time to "build up" CTL.
I'm using 12 and 45 right now.

Second, I have the feeling that when I do really hard intervals, like 5 x 1 km way below my current 10k race speed in anaerobic territory and reaching up to 95% of my heart rate reserve, it does give me relatively few TRIMP points - compared to let's say a relatively easy run at constant speed and maybe at 69% of heart rate reserve (that would be around 77% of maximal heart rate).



yes Michael..i have the same age 'problem' and question. I share EXACTLY your 5x 1km issue with TRIMP.

also does it apply to triathletes who do, say, only 2 lots of running 2 lots of swimming and 2 lots of biking each week compared to 6 lots of running for a runner?
also does it equally apply to IM training as say to someone training for one mile racing.

just wondering!
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Re: Time constants for ATL and CTL

Postby ghinop » Fri Dec 30, 2011 6:09 am

Since TRIMP is calculated based on the score for each heart rate zone, you may edit the default score rating so that the score of higher HR zones (i.e. close to HR max) is non-proportionaly higher. For example:

settings.png
Settings
settings.png (106.39 KiB) Viewed 3456 times


If you plot the above score rating you see that the relationhip between score and %HR is non-linear after 160bpm.

chart.png
Score chart
chart.png (13.23 KiB) Viewed 3456 times


As a result, activities that are perfromed at a HR close to HRmax will get a much higer TRIMP value.
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Re: Time constants for ATL and CTL

Postby the5krunner » Fri Dec 30, 2011 11:57 am

If you gave the highest zone a factor of 1000 the TRIMP would be even higher...but it would not mean that it was 'correct'. So how did you arrive at the factors you use please?

Glad you made me check these though as for some reason a few of the factors were blank so I filled the gaps in!
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