Have you ever stopped to think about the connection between the hamstrings and the pelvic floor? I mean, unless you actually really think about it, it's not really common dots to connect! But your hammies attach to your sitz bones which are at the base of your pelvic bones. So if they are tight, they can pull the pelvis out of place. If they are weak, it can create instability in the pelvis and then other muscles like the glutes and pelvic floor have to compensate.