My squat is pathetic; I can get to parallel, but have problems breaking it. I have been told by a very good source that my hips and legs are tight, which is preventing me from breaking the plane. However, wierd question, but the other day I was standing on a slight hill waiting for the dog to do his business, and started practiceing my squat. Wierd I know; however I notice that I was able to break parallel which made me wonder about shoes. I wear Chucks during spuats, but I was wonder if squat shoes with a raised heel would give the little extra to break parallel.
Yes, a raised heel will make it easier to hit depth.
I would also address the form/flexibility issues that prevent you from hitting depth. Focus on externally rotating your hips by really pushing your knees out and I bet you break parallel a lot more easily.
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Raised heels helps mid to narrow squatters hit depth. They dont help wide stance much though.