Changing to HIIT, the original title of this thread, so was going with that. And there is HIT, which is more geared towards actually BB'ing. HIIT geared more towards general performance, fat loss, higher functioning metabolism, stamina, etc. and like goals. Can use weighs with HIIT, but can be adjusted to bwt movements and short distance running. 40 yards sprints (football) give excellent results, and in a short time. Even punching a heavy bag, anyone can use the HIIT method on just about anything. After starting any new style program, allow a good 2 to 3 weeks breaking in time. After that and 5 or 6 weeks should tell you if it fits your needs or not.
I've mentioned my experience with PHA quite a few years ago, and often. The famous Chicago Duncan YMCA was where Gadja (Polish-American) trained and taught, probably in the mid to late 60's(?). Sergio worked with Gadja for a while using PHA (Perpetual Heat Action). Gadja wasn't overly massive but, for that time, exceptional muscular balanced, very low body fat. Used PHA, on and off, for a while, as I had mentions before. Slanting more towards the Tabata protocol , seems to suit my needs.
Gadja's ideas was to avoid the pump and not allow blood to linger in any body part , but keep it flowing. He include isolation exercises right along with heaver compound movements. If he did squats he would, with zero rest, grab a DB and do concentration curls, then to situp,DB flys, etc, etc.. for example.
Good Luck.