Does anyone know why 42 days is the time frame used for CTL, why not 30 days, or for that matter 52 days? Is there any research out there that supports the 42 days?
It takes about 6 weeks (42 days) to see changes in training.
1 Like
Thanks for the response Gerald. That’s my understanding as well, but as we all know, athlete response to training is very individualized. What I’m really interested is finding any research that explains how the 42 days was arrived at. My guess is that if there was any research done, the results probably showed individual variation but 42 days was the “average”. I would hope there is research and 42 isn’t some number somebody just pulled out of thin air. I’ve engaged Professor Google to see if there is any research out there, but not finding anything, hoping someone on the forum may have some links they can share.
Have you read this?
It gives a lot of info on how the time constants are derived and will give you enough info to keep searching.
42 is regurgitated everywhere with zero context as to where it came from and to whom it applies. 42 is for what phenotype of athlete with how much training age and etc., etc?
Clarke and Skiba have a method of determining personalized time constants and they give you a way to estimate how much taper you need before a race. You’d need to do regular time trials to develop the impulse response model.
1 Like
CTL is the trademark of TrainingPeaks, and is set at 42days as default. I don’t have anything in research to show why it’s that number. But it’s a marker (42 days), so when you look at the data you will know that CTL will also be the last 42 days.
However, CTL also tells a story, over time, eg. the line increasing or decreasing will tell you if your training is building or not. Another is the slope; a gradual slope would indicate a steady increase in “fitness” and a steep slope would indicate a possible overload and potential risk.
1 Like
I get CTL is a trademarked name. However, PMC is based on Bannister’s Impulse-Response model. In the link I attached there’s at least 6 papers mentioned that investigated the time constants.
All my point is, is that CTL, or long term fitness is not 42 for everyone and using 42 and 7 just blindly for the PMC is not good practice. However, developing personalized time constants is beyond most people’s abilities.
2 Likes
A lot of the text in the link you posted is also showing in his book “Training and Racing with a power meter”, so it’s familiar to me.
1 Like
That’s cool. I posted that link for OP. They seemed to want some additionaI info into where 42 comes from.
1 Like
Thank you, this is great info, I’ll need to read through it a few times to digest it.