Confession: I (gasp) cheated and skipped doing the matrix at stage 3. Mostly, this is because some of the other stage 3 exercises were already making me feel like a bit of a freak show - had already gotten quite a few comments about the db single-leg romanian deadlift and db single-arm overhead squat. Yesterday I started stage 5 and decided to suck it up and just do it.
Got through the regular squats and lunges thinking "this isn't so bad... what was everyone complaining about?". Then I started on the lunge jumps...
OMFG!!! I couldn't even finish the full set, my thighs were going to explode. Needed to take a break to finish the set, a few breaks to finish the second and could barely drag myself back to the locker room afterwards. Wow. Feeling it today, that's for sure.