Pelvic tilt goes something like this:
And it's caused by tight hip flexor muscles. You have 4 hip flexor muscles: the Psoas, TFL, Iliacus, and Rectus femoris but non the less your hips tilt fwd and you put yourself in a poor mechanical position that can lead to nagging injuries and you just plain and simple wont be able to perform as well, plus you'll look like you have a belly (see above).
Your glutes wont be able to fire correctly or as efficiently as they could b/c they are inhibited by the tight/shortened hip flexors.
This will put the hamstring in a pre stretched position b/c the posterior portion of the hips are higher than they should be. This is bad. You know any athletes w/ nagging hamstring issues.....it's probably b/c their pelic tilt sits to far anteriorly.......Not good.
Anterior pelvic tilt will also lead to an increased lordosis. In other words your lumbar spine (lower back) is going to have too much of a curve.
Sounds like no big deal right? I mean, it already curves right? Well, increasing the curves of your low back means you aren't as tall, your belly will stick out further making you look like you have more bodyfat than you really do, it's really bad for your back, will probably lead to pain, and its potentially not healthy for the nerves that innervate that area.
What to do
Working on stretching your hip flexors will go a long way.
Most people will need more than that though, and that's where activation and strength comes in.
Next post will be on stretching and lengthening the hip flexors, activation, and strength work.