Originally Posted by
Connor Walsh
You seem to be doing a good job at setting your low back in extension.
Yes your last rep looks like a squat-morning. You are driving your hips up out of the hole (good) but your chest is staying where it is (bad) and you're bending over a little too much. The bar moves forward of the balance point over the mid foot and the rep turns into a grinder. The torso should move up as a single rigid component.
Focus on driving your hips up and keeping the bar over the middle of the foot. If you do this correctly your body will assume the correct back angle for the squat.
You elbows were twitching because you relaxed your upper back muscles when you were straining to stand up. Get tight, stay tight.