what is your 5RM lunge/5RM squat, for example, when you trained that way?
for example, when I was doing 225 lb barbell walking lunges for singles, the max was probably around 235, and my half squat was 315 x 1, at 165.. the walking lunge singles were extremely intense.
I did a variation of the forward lunge, where I make a step forward and drop into the lunge position and then do an explosive concentric with the forward leg to get into the starting position directly. I did those recently with 225 lbs for 3 sets of 10 reps (alternating legs) after my squats, 3 rm must have been between 402 and 408 lbs for the squat on this day (unusual training time). That was my third lunge session, so it might not have been a true 5 rm in the sense that coordination can still improve and I started out rather conservatively (198 lbs for mentioned reps/sets two training days before). But they were hard enough to get a sense of the trunk activation and IMO it does not compare to a heavy set of 5 in the squat.
why wouldn't you use unilaterals for beginners? or did i misunderstand.
and is this for performance, or just strength athletes?
During a squat for example, the outer quad(vastus lateralis) is recruited more than the inner quad(VMO). This will eventually lead to an imbalance, which if ignored can result in the knee 'caving in' b/c of the lack of strength of the VMO which may lead to injury. This is also why the VMO is heavily rehabbed in ACL injuries, to prevent further injury and 'caving in' of the knee. This is coming from experience.
wow i always thought the knee caving in = internal rotation of the femur which happen be because of tilted pelvis (which could suggests weak glutes and abs), or weak just glutes/hams....corrected by hip extension exercises focusing on keepping the knees in line with the hips/ankles, coupled with glute activation
My knees came in during the squat a lot at the beginning. I fixed this by taking weight off the bar, correcting the mistake and work up from there. I got a lot stronger and did not have this problem anymore. No unilaterals needed. Whatever is the cause for this problem (Mark Rippetoe argues that it is actually week adductors), it went away by performing bilateral work correctly.
Everything else really has already been addressed.