I wasn't aware that there was such a thing as a "TrainingPeaks/TSS model" or approach to training. Maybe you can tell me what it is?

The takeaways, in my opinion, are two fold:
- the value of a lot of very consistent but easy training.
- the benefit of only a few very hard sessions.

Others can weigh in on the nuances, but the TrainingPeaks Performance Management Chart is an implied model or approach, e.g. it maps training stress onto improved fitness using a fancy formula. I'm not in a position to gauge whether it adequately acknowledges the need for rest or the impact of recovery workouts, though. Hope this thread triggers a lively discussion of these topics!

I know what it is/does (see my .sig).

Yeah, I agree. Rappstar totally missed the mark on this one. TSS is scaled to volume and intensity. TP is a platform, and great one at that, but it's use alone is not going to decide what kind of adaptation come.

Without guidance, it is fairly easy to "discover" that the best CTL chasing technique is to go high volume medium hard day after day since you can accumulate large TSS.

The problem is that what is "really" considered easy what is considered "hard". Maybe this is personal or maybe its not.

Swim: ????
Bike: Is easy less than 60% FTP, <65%, <70%? What is hard? >100% FTP
Run: HR based on LTHR or Max HR? Based on Threshold speed? What are these zones?

Came across this infographic, which I thought was elegant in its simplicity and also quite effective in communicating a somewhat complicated topic.



The middle one is the worst. And yet that is the one that I believe is typified by most common training plans, especially the trainingpeaks/TSS model. It "rewards" a lot of "kind of" hard work, and yet I don't think it's actually necessarily indicative of what provides the most effective stimulus. I realize that the TSS model has had a lot of success in cycling, but I think it's a lot less applicable for triathlon, especially because there's really no good way to measure TSS in the pool and because I think it undervalues the impact of easy running, which I think are much more valuable than easy cycling...

The takeaways, in my opinion, are two fold:
- the value of a lot of very consistent but easy training.
- the benefit of only a few very hard sessions.

The ideal mix is a combination of high and low intensity, with only moderate middle intensities. Basically, minimize how much so-called "sweet spot" training you do, because it is not at all the sweet spot...

Credit for the photo goes to Mike Young, PhD on Twitter - @MikeYoung

Hmm, perhaps I didn't express myself very well, I think your chart agrees with what I was saying. Suppose I am shooting for a CTL of 100 for some reason. It would be super hard to do that with 1hr a day (at least for me). But your chart shows nicely that I might do at at 2hrs at IF=.7, or maybe even 3 hrs at .6ish. Both of those seem quite achievable and what I was calling "medium hard" (e.g. IF<=.7)

https://www.youtube.com/watch?v=LZ0epRjfGLw

Let me see if I can put the "criticism" another way. NP/TSS/CTL is a huge step forward; I've seen personally and for others that it comes as a bit of a revelation in terms of providing a metric for their cycling. The trap is that used naively, what you measure naturally becomes what you optimize, so I've seen a tendency for people (myself included) to tune their training toward higher TSS/CTL at the expense of training mix. If there is a training mix that an individual finds easier to achieve the same TSS, they will tend toward that even if it is not what would best achieve their training goal. Thus, the particulars of the measuring tool can accidentally shape the direction of training in sub-optimal ways. Addressing that shortcoming is a place where proper coaching, training plans, and/or the use of additional metrics that provide ways of measuring other dimensions of training can help add value.