Pelvic Tilt

Potentially the most important muscle group, the core is composed of all the muscle from hips to shoulders. It effects full body movements as well as maintaining posture throughout movements. The core effects the transfer of energy from the lower to upper body. A strong core improves all aspects of golf from maintaining posture to increasing club head speed as well as helps prevent injuries

Starting position:

Laying in a supine position with knees bent, back flat, head neck and shoulders relaxed.

Movement:

Without flattening, or arching your back, tighten your abdominals with the feeling of bringing your belly button in towards your spine, and up towards your heart. Also think of gently trying to hip they hip bones together as if you are trying on a tight pair of pants.
THEN, once your abbs are braced, using only the lower abdominals, pelvic tilt to flatten your back against the ground. To do this feel like you are trying to pull the front of your pelvis UP towards your ribcage, without using your legs.

Notes: when done correctly, it should be felt mostly in the lower abdominals, and the stomach should maintain being pulled in, and up, not “pooched” out.