I’ve been using Power Tap for a couple of years now but have become hazy on correctly setting the numbers on the Cycling Peaks software for ATL (Acute Training Load) and CTL (Chronic Training Load). I know one represents load over a longer period of time time one represents training load more recently. They both default to zero but my understanding is I should put the number of times I am riding a week in each field? Correct? When should I modify these numbers as well? Any help is appreciated.
Here’s a response I provided to a similar question on another forum a while back:
Quote: Originally Posted by fezzy I have been using a PowerTap since the middle of December along with CycingPeaks. I believe I read somewhere about prepopulating the fields in the PMC with some made up numbers. I have tried, but didn’t really know what I was doing, so I have since set them back to 0.
The problem being my TSB is ranging from -30 to -40, obviously not correct. Will the chart correct itself once it has enough data to accurately define my CTL, or should I prepopulate the CTL/ATL. And if so, based on what? Thanks
Answer:
It will settle down after 3 months. It will settle more quickly if your seed CTL & ATL values are reasonable estimates. Leave the CTL & ATL Time Constants alone for now.
** To *estimate *seed values: **
ATL = (avg weekly hours for previous two **weeks **before PMC start date) x 8
CTL = (avg weekly hours for previous two **months **before PMC start date) x 8
e.g. if for the 2 months before the PMC start date you averaged 7 hrs of on bike training per week, then CTL seed value ~= 7 x 8 = 56.
That assumes an average Intensity Factor of about 0.75 for all rides in this period.
That’s a reasonably normal training intensity.
If training has been moderate, then x 7
If training has been hardish, then x 9
Thanks for the response…wanted to make sure the other poster and I were talking about the same thing. The fields to which I was referring are the manual input fields (no toggle buttons) directly below the CTL and ATL with toggle buttons. The webinar with Hunter and AC said to set the toggled fields at 42 and 7 respectively, giving you the broadest look at your data. But I got confused on what data is inputted in those fields below the toggle fields. Am I just really confused…or making this confusing?
PS- The data I have is from January 8th to today so I have plenty of data…thx again.
Those fields are for seeding your initial performance manager chart with estimates of CTL & ATL at the time of the chart being started, using the method I described.
IOW, if you had been training up to the point when you first started to collect power data, then it makes sense to “seed” the starting values of CTL & ATL. That way your PMC will look a lot closer to reality much earlier than say waiting for 4 months of TSS data for it to settle down.
The 42 & 7 values are the CTL and ATL time constants which represent the half life value in days of the TSS used in calculating today’s CTL and ATL.
Just to emphasise my point, following is a picture of the same Performance Manager Chart for an athlete covering a 7-month period from September through March with the only change being the seed value. In the top chart the seed values for ATL and CTL are zero, in the lower chart both ATL & CTL seed values are set to 40 TSS/day.
As can be seen, starting at 0 CTL may show an artificially high ramp rate in the first month or two (especially if you have already been training). But it starts to settle down so that the charts essentially match after a few months.
In the case of this athlete, they had not ridden a bike for ~ 6 months due to serious health issues, so starting at a CTL/ATL = 0 zero was appropriate.
If you have several month’s of TSS data prior to the start date for a chart, or say are starting a new chart for a new season, then there is no need to seed the chart - it will pick up the historical ATL & CTL starting values automatically.
