The torso stabilizes the spine and allows movement by coordinating with the pelvic muscles. These muscles work together to flex, extend, rotate and bend. Torso rotation exercises can improve movement involving flexion and extension or bending forward and backward. The benefits of torso rotational exercises include increased mobility and strengthened obliques, but doing these exercises while seated may cause back pain.
The primary areas affected by torso rotation exercises are the rectus abdominus or abs, transverse abdominus, and obliques. Secondary muscles groups affected are stabilizers such as the rhomboids, deltoids, glutes, abductors, quads and adductors.
Torso rotation exercises primarily work out your oblique muscle group, which can add power to rotational motion. Athletes in certain sports, such as shot put or golf, may benefit as the exercises improve the strength of their swing. Additionally, stronger abdominal and back muscles take more pressure off the spine.
Scoliosis is a medical condition in which the spine curves between 10 and 45 degrees, with more severe cases reaching 80 or 90 degrees. Generally, patients suffering from extreme cases undergo an operation to have steel rods inserted along their spine, but a study by the US Spine and Sport Center of San Diego published in the February 2003 edition of "Orthopedics" indicated that performing torso rotation exercises can not only stop the curve from getting worse, but may also correct patients' spines before the 40-degree mark is reached. Because scoliosis patients suffer from asymmetric thoracic muscular development, the isolated strengthening of the muscles that rotate the torso appear to improve the weaker side.
Torso rotation exercises may strengthen the oblique muscles, but do little to reduce waist fat. While the obliques are located under the area generally known as 'love handles,' working the underlying muscles will not cause fat loss in that area because targeted spot reducing with exercise is not possible. A comprehensive weight loss program will generally lead to fat loss all over the body and not just in one area.
Spine and Back Issues
Performing torso rotation exercises while seated can result in spine and back pain. The abdominal and core muscles stabilize the pelvic-lumbar region and control acceleration/deceleration of the spine, but this is best accomplished while standing on your feet. Isolated dynamic rotation training involves movements that are contradictory to lumbar biomechanics by fixing the pelvis while rotating, which can bend the spine and result in a delamination/disc- related injury.
The risk to your lower back can be minimized by avoiding the extremes in range of motion while seated or by only performing torso rotational exercises while standing up, thus allowing the pelvis full rotational motion.