How do high bar , low bar, front, safety bar, and zercher squat differ biomechanically, in muscle activation, and muscle fibers activated. Also how could these be used in a work out for building maximal strength synergistically within a prolonged program regimen.
muscle fiber activation has to do with rep, set, volume, intensity, and tempo of lift, not the lift itself.
high bar has you more upright so there is a shorter lever on the hips.
low bar forces you to lean over most and causes a longer lever arm on the hips.
front is similar to high bar but still tries to throw your forward like a low bar. it doesnt require a lot from the low back but does from the upper back. it uses less weight so less loading on the spine but can still apply plenty of force to the legs.
safety bar exagerates the low bar squat.
zercher is like front squat and a cambered bar combined. it requires less from the upper back.
as for using them in a program. you can train it just like any other lift. or use it to bring up a weak link for another lift.