Hiya - I've worked with Frantic a bit. Obviously a lot of stuff is done with trust excercises and multiple bodies which is difficult. With isolated individuals, I think they talk quite a lot about how to start movements using a single body part and follow that through the rest of the body. Can't remember the actual way they name it, but I think their book has a fair amount about that: https://www.amazon.co.uk/Frantic-Assembly-Book-Devising-Theatre/dp/0415467608
There is quite a bit of material out there on Frantic, mostly due to the lovely tradition of british theatre to educate and share their knowledge. If you google Frantic, some pdfs will show up. And then there is a book they wrote themselves which is highly recommended, not just for info on Frantic, but devising techniques in theatre.
As for Brecht, there are plenty of books. This might be a good start