Re: What is what with Scott Sonnon's material?
I use kettlebells and bodyweight exercises, but I think it's probably a bad idea to try to use them to build frame or internal strength. Doing those (kb's and pushups) correctly (in the traditional manner) isn't consistent with internal strength and the levels of resistance would probably engage local muscle too much.
I use kettlebells and calisthenics to build overall strength for health and fitness, but I consider it completely distinct from my internal strength work. I'm not doing them to build internal strength and don't expect that work to have any impact (except this one...the stronger my legs are the more ultimate power I can generate, internal or external).
I know the arguments that you must not do any weightlifting and etc. if you want to develop internal strength, but I'm skeptical. Nothing from what I know of motor control and learning or skill development and specificity provides a rationale for that...building internal strength is very difficult and requires work every day, an active approach to re-training the body. I don't see how a couple or three days per week of specific strengthening of local muscles makes that effort much more difficult than it already is. That would almost suggest that one's muscles should be weak in order to build internal strength. Ummmm, I don't buy that. It's, imo, the habitual ways we tend to move our bodies that is the impediment, much more than specific, limited things we do to strengthen the limbs and core.
I am, in a pretty limited way, using a weightvest with some aunkai, taiji, and xingyi drills, I've chosen a resistance (5 to 10 lbs.) that, since it's distributed over my torso, doesn't load up my shoulders or impinge my breath as I work. I anticipate very gradually adding resistance but pretty closely monitoring things so I don't get off track. I think that approach, loading an additional resistance over the body, may be more productive than trying to adapt kettlebell drills.