This isn’t a hard and fast rule. While it does decrease knee torque slightly, it results in a huge increase in hip torque because your trunk must lean forward more to compensate. And that’s not a good thing for your hips or your lower back.

You shouldn’t have your knees go half a foot past your toes, but it’s perfectly acceptable for your knees to go past your toes a little if that’s a natural position for you. Everyone is proportioned differently. So while some can squat comfortably with the knees never passing the toes, others could risk a lower back or hip injury by sticking to that rule. What you don’t want to happen is to have your knees roll to the side. I’d worry a lot more about keeping your knees in position laterally than whether they go beyond the toes by a couple of inches.

We are born knowing how to squat. The torso is made to drop down low between the legs with the knees and feet going outward in a slight angle. It’s the bending-over-at-the-waist to pick up stuff that isn’t natural, even though most people do it. My two year old routinely squats down to pick up stuff from the floor (and sometimes put it in his mouth). He simply drops his torso down below his legs and maintains a neutral spine because it’s comfortable for him. His knees go past his toes because he’s proportioned like his old man. It’s just the way his body and mine are built.

GREAT POST on a too oft neglected exercise.

1. Performing bodyweight squats while facing a wall – Get nice and close to the wall – Your toes should be about 6 inches from the wall. Cross your arms across your chest, and by following the Lazy Man’s tips – SQUAT.

If anypart of you touches the wall, stop and back off an inch and try again.

2. Another trick is to perform overhead squats. Starting with a broomstick, press your arms overhead, reaching for the ceiling.

Now try squatting – always reaching for the ceiling. This will keep your spine elongated. You may find that you can’t go very deep and keep reaching for the ceiling. Give up depth for the time being. As your hips limber up and your leg strength improves, you will be able to go deeper and add some weight to the overhead lift.