The search for the best core exercise is endless. Every trainer seems to have his own ideas about the most effective method to train the core. Most agree that functional training is the first step to total core fitness, but that functional exercises must be supplemented with a core-activating workout. Some trainers advise circuiting a few exercises or using med balls or a physioball. Others avoid crunching exercises and focus instead on Planks.
One core exercise rising to the top is called the Turkish Get-Up. Although some have expressed skepticism because of its bizarre and unfamiliar movement patterns, it is reputed to be one of the most effective total body core exercises, and it’s incredibly challenging.
Mike Boyle, co-founder of Mike Boyle Strength and Conditioning, was once a skeptic. He says, “If you’d have asked me a year ago, I would have said the
 Turkish Get-up was a gimmick. Now I think it’s probably the 
best total body core exercise you can do.”
Start by lying on the floor, holding a dumbbell in one hand overhead. Then, while continuing to hold the weight overhead, simply stand up.
The Turkish Get-up activates core stabilizer muscles that cannot be developed with a standard Crunch. The movement also helps build shoulder strength and stability, which is important for safely transferring core power to the arm when executing a sports skill like pitching a baseball or swinging a tennis racquet. When the exercise is completed, you’ll have used a wide array of muscles in your legs, hips, abs, back, chest and shoulders, making it one of the most effective total body core exercises.
Source:  mboyle1959.wordpress.com