This exercise strengthens the trunk musculature in the transverse plane, often a weak plane of movement for most people. Because it is sometimes a weak area, it can often be the source of injury in work and sports activities. This exercise focuses on the core, working the External and Internal Obliques, and the Posterior Spinal Rotators. It's great for anyone training for a rotational sport such as tennis, baseball, and even at work or home, like moving furniture.

• Sit on the floor with knees slightly bent while holding weighted resistance, such as a medicine ball.
• Maintain a neutral spine (back aligned straight), and pulling abdominals in tight by drawing your belly button inward.
• Touch the medicine ball to one side as close to the floor as possible without bouncing off, and rotate over to the other side.
• Repeat 30 repetitions alternating to each side.

Important Tip: Do not allow your body to move into a hunched position. Always keep your abs tight.