Another TSB Question

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For the PMC I have the default values of 42 for CTL and 7 for ATL. I realize TSB is the difference between the two, but I had about 2 weeks off the bike a month ago and was swimming, running more regularly. I did not enter any guestimates for those sports, and currently PMC shows..

TSB -46
ATL 113
CTL 65

Does the default for TSB go back 42 days?

I am assuming the swimming and running would in theory raise the CTL and lower the TSB.

I do not plan much of a taper because I am more set on improving for the year than one race result.

Any thoughts?

For the PMC I have the default values of 42 for CTL and 7 for ATL. I realize TSB is the difference between the two, but I had about 2 weeks off the bike a month ago and was swimming, running more regularly. I did not enter any guestimates for those sports, and currently PMC shows..

TSB -46
ATL 113
CTL 65

Does the default for TSB go back 42 days?

I'm not sure I completely understand your question, but hopefully this will answer it: the half-life of an exponential response is equal to the natural log of 2 multiplied by the time constant (or, conversely, the time constant is equal to the half-life divided by the natural log of 2). Thus, when using the default time constants of 42 and 7 d for CTL and ATL, respectively, we're talking about half-lives of ~29 d and ~ 5 d, respectively. IOW, the CTL value primarily reflects what you've done in the past ~3 mo (since three half-lives = 87.5% of the way to plateau), whereas the ATL value primarily reflects what you done in the past ~2 wk. Since TSB is calculated as the difference between the two, it doesn't really have it's own time constant/half-life, but obviously it will track much more closely with ATL than CTL.

I am assuming the swimming and running would in theory raise the CTL and lower the TSB.

That is correct. The only tricky part is in trying to decide how much "credit" (i.e., daily TSS values) to assign to your swimming and running (an issue I faced recently when my wife decided to stop running and start riding again). On the one hand, there would be only limited crossover in terms of fitness/performance (due to the specificity principle), which would tend to lead you to discount such training (i.e., assign lower values). OTOH, running at least is going to cause more muscle fatigue/damage than cycling, which would tend to lead you to give more credit. It's a tough call...