4DP is a copy of Coggan’s Power Profiling. Wahoo just stuffed all efforts in one workout. Here are a couple references:
Another explaination:
If you want something kind of close to INSCYD, you can also DIY using this Python notebook. It’s based on Mader’s model, which is what INSCYD is. The python notebook won’t do the complex workout simulations that INSCYD also offers. I stopped trying to measure and use VLaMax after I spent lots of time sprinting and sampling in cycling and running. I find that if you know VO2Max and CP/MLSS to a good degree, back calculating VLaMax is easier than trying to measure it.
This paper is what INSCYD is partially based on. You can find INSCYD’s patent online to read if you want.