Dead Bug

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:

Start by “bracing” the abdominals (see abdominal bracing) once your abs 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.
Extend the arms above the shoulder and while maintaining braced abs, and a proper pelvic tilt, lift one knee to 90 degrees, then bring the second leg up to the table top position.

Once stable, extend one leg out, as if rolling a golf ball down the floor with your heel, while also extending the OPPOSITE arm overhead. ONLY go as far as you can without allowing the back to leave the ground, shoulders to tense, or stomach to push out. Alternate sides for time, or reps.

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.