On the disadvantaged body type issue – there definitely is such a type (femur long relative to torso and lower leg). It is not impossible to do a good squat but it is significantly more difficult. It requires greater ankle flexibility and greater hip flexibility. The torso also will lean further forward in order to maintain the centre of gravity over the feet (because the femur is longer and so the top lever – the torso – is starting from further back in relation to the centre), putting more pressure on the lower back. Finally, in order to achieve a similar squat position to someone with more advantageous leverages, a disadvantaged squatter will also have to move the bar a greater vertical distance and so they will also be doing more work per lift. If they are doing a full squat, their ass may literally be touching the ground, or close to it. Even to do a just below parallel position, they are going to have to squat quite deep. This is all just basic mechanics.

For years I tried to develop a full squat. People with short thighs kept saying I was just not flexible enough, even though I could see that my ankle flexion, for example, was better than theirs. They were right, but they didn’t tell me that my flexibility had to be significantly better than average in order to achieve the full squat position. At some point I decided to be very stubborn and systematic about it. I started doing squats at home, barefoot, without weight. Initially, this would involve a lot of back rounding but I didn’t worry about it at first. I did my best to maintain a tight, straight back but made note of when the pelvis began to “tuck” on the way down.

I also began systematically stretching all the hip, torso, and leg muscles.

In the gym, I would do (and still do) a lot of squats with an unloaded bar or with very light weight (10 lb plates or at most 15). I would work first on the front squat, where it is easier to achieve depth because the torso can maintain a more upright position. I’d also do narrow grip overhead squats, going as far as I could while maintaining a good back posture. (Mel Siff recommended these for improving squat depth.) I’d do back squats and wide-grip overhead squats. I would do all of this sometimes in my socks, sometimes in sneakers, sometimes in weightlifting shoes. In the meantime, to maintain lower body strength, I did heavy lunges, split squats, and half or almost-half squats.

I can now do full squats in all positions. It took a couple of years to achieve this. In the back squat the torso still leans forward quite a bit, especially with an unloaded bar, and there is tucking at the bottom, so I’m still working on that. The overhead squat is actually easier to achieve depth in while maintaining back position, because the bar can move somewhat independently of the torso to maintain the centre of gravity over the feet.

Because of my body type, I avoid all deadlifts, except for a Romanian-type deadlift with an unloaded bar, starting from the hang, which I do for a stretch. I only do snatches and cleans from the hang or from blocks. It’s just too easy to slip into a rounded back position and cause injury, and it’s not worth the risk for me.

Find a staircase. Sit on the bottom step. Then stand up. There, you’re deep squatting.

All that did is remove the “down” part. I’ve never found anyone who couldn’t do this. You simply have to start in a different place.

Re: rounded back deadlifts: No, RBDL are not ok. The spinal musculature is what stands between you and your spinal ligaments exploding all over the back wall. The ligaments can take some abuse but eventually the freebie runs out. When the spine is flexed/rounded the spinal muscles are electrically “silent”, aka sitting on their asses doing nada. I recommend Stuart McGill’s research on this subject at backfitpro.com

2. I’ve tried for YEARS to develop the kind of flexibility
that would allow squatting in the ideal form that you describe.
(Same with deadlifts). No go. Just wasn’t happening, no matter
how much I tried and practiced. So, some while back, I said
“fuck it, I’m going for it anyway, even if in ‘bad’ form”.
And the results are… so far, so good. I’ll report more later.

I read recently that there is such thing as a “squat-advantaged”
body type, and “squat-disadvantaged” type; the advantaged type
has a longer torso and shorter legs, and may have differently
placed muscle attachments. In any case the advantaged type
CAN squat in this ideal form: feet flat on floor, pushing
through heels, no drift forward. Well, I am in no way the
advantaged type! I’m the opposite of that, in spite of my
best efforts over a long time. But I’m squatting anyway —
and benefiting, so far. Again: I’ll report more later.

Same with deadlifts: rounded back! Cannot avoid it, so I’m
not trying to avoid it anymore. Results: so far, so good.
(And I’m a person with a history of low back problems, so
if I’m doing something wrong, one might expect it to show
up quickly. So far — 2 years — it hasn’t.) Interestingly,
I read recently (several places) that the “keep a flat back”
mantra actually has no basis, and that rounded-back deadlifts
are perfectly OK (?!). So now I’m really confused,
intellectually. But fine, physically, benefiting from my
rounded-back deadlifts, getting stronger all the time.

I’ll let you know if I’m suddenly rushed to the hospital with
an acute lumbar injury requiring emergency heroic surgery. ;-)