We commonly mistake a feeling of tightness with being “tight,” or having shortened muscles. More common than not I find that people are more flexible than they think. Often times, you are unable to touch your toes or squat. However, when we put you in a position that is not gravity dependent, like lying on the table, your hamstrings, hips and ankles demonstrate more than enough flexibility. Be careful mistaking a feeling of tightness for actually having “tight” muscles (or short muscles).
This video demonstrates a good way to see if your limited squat is due to a flexibility issue or a “programming” issue. Meaning your coordination, balance, timing, etc. are not quite up to par. This video also demonstrates a cool drill I stole from Gray Cook. You can find other great information from him on Youtube or at graycook.com.