It's about the Hips
Good example in a single session in the before and after of getting a horizontal hip presentation. In this picture you can see the elevation in her right hip has shifted down making her overall structure more even. Her hips are more horizontal and more even left and right from the hip crests to the axilla and there is a corresponding slight increase in overall length. The belief is in creating a better overall alignment with individuals translates into a better movement pattern with less pain.