Incorrect pelvic tilt is something we see a lot of in surprisingly a range of lifters with varying degrees of experience.
We certainly do find that beginner to intermediate lifters suffer more so from a lack of quality positioning inhibiting their potential and increases the niggles/injuries they run in to.
Here we want to talk about pelvic position, which is important for movement quality and efficiency.
In terms of movement ability we are all able to put our pelvis in to an anterior and posterior pelvic tilt by either rolling the hips forward which will create a bigger arch in the bottom of your back, or we roll the hip backwards which flattens the arch out.
In either position we would be considered out of neutral, or in a position where the segments of your spine are not stacked evenly.
When we perform loaded movement, like this example in the squat, we want our spine to be in a rigid neutral position, particularly the lumbar region. Rigid meaning we DO NOT want it to move, it must be stable. We create stability through correct bracing techniques where our trunk musculature is engaged in proportion with the load we are moving. This enables us to maintain a nice stable spine.
A neutral pelvis will result in a perfectly loaded lumbar spine where all the segments are stacked evenly on top of each other and the muscles of the trunk are engaging in a harmonious and synergising way to hold that position.
The images in this post show what it may look like in the hole in either position, both not great in terms of quality and efficiency.
In an anterior pelvic tilt you won't be able to hit sufficient depth as you are jamming up the anterior compartment of the hip, which also won't feel great. You'll also notice the lower back will get pretty fired/jacked up.
On the flip side, the posterior pelvic tilt will allow you to get depth but there is an increase in shear-forces on the lumbar spine and therefore potential for lower back injury.
Both positions also do not facilitate an efficient movement where you are able to produce and transfer the most force.
If you need some help with this, reach out!