Sports are multi-directional, meaning movement takes place in a variety of planes and positions. It is vital to perform exercises that develop your strength, speed and agility in all directions.
Most drills affect only the sagittal plane [front and back of body]. Few programs include exercises that work the frontal [side to side] and transverse [rotational] planes, leading to diminished strength and slower performance. And one area that is almost always overlooked is rotational stability [or de-rotation]—despite the fact that it is essential for optimum performance and injury prevention. Training to resist rotation is critical to protect the low back.
The term “rotational stability” seems like an oxymoron. How can a person be rotating and stable at the same time? A good example is the golf swing. Although most of its power comes from the hips, the core must stabilize the spine and ribcage to prevent unwanted movement. During rotation, if certain areas cannot stabilize due to muscle weakness or lack of flexibility, unwanted movement will occur, power will be lost and performance will suffer.
Try these three exercises to build a base for rotational stability.

Pallof Press
The goal of the exercise is to maintain a neutral spine in an athletic position while resisting a rotation stimulus.
Start with a wide base to get the feel of the drill, then narrow your stance when you feel more comfortable. With tension from a band, cable or partner holding a towel, press your arms out straight, creating a rotational force that the hips and trunk must resist. Relax your neck and traps [upper shoulders]. Focus on a firm grip and a tight core to increase stability and decrease the need to engage the traps. Hold for a predetermined time. Face the other direction and work the opposite side.
Work toward a narrower base before jacking up the weight. With more weight, you will get greater upper trap recruitment. This is normal, but the goal is to work through the core, hence the narrower base.

Three-Point Plank With Band Pull [Plank Pulls] Assume the plank position: forearms on the ground; elbows directly under the shoulder joints; toes pointed into the ground; and knees, hips and core lifted so the body is in a straight line.
Holding a band in one hand, lift the arm up and extend it straight ahead. With tension on the band, flex the elbow and perform Band Pulls, bringing the hand back toward the shoulder. Extend back to start position, and repeat for specified reps. Maintain stability through the body and make sure you don’t drop your hips or rotate your shoulders to get more movement.

Physioball Toe Taps
Assume Push-Up position with both feet on top of a physioball, toes pointing into the ball. Holding a rigid position, lift one foot off the ball and bring it down beside the ball, tapping the floor. Bring foot back to start position and do the other leg. Repeat back and forth for specified reps.
Again, make sure to maintain stability through the core and don’t drop the hips or rotate the shoulders. Movement should come only through the hip joint.
Photos:  howtoimprovegolfswing.net, christopherdhoward.wordpress.com