Major Muscles and Actions Involved
In side bends the quadratus lumborum, the internal oblique and external oblique, the rectus abdominis, and the erector spinae muscles are involved in lateral flexion of the spine. In this action the trunk is pulled over to one side via contraction of the muscles on the same side of the body midline.
Muscles in Action
This exercise is important for all athletes who throw overhead for maximum distance or force (baseball pitchers, outfielders, football quarterbacks, javelin throwers). It is also important for overhead hitting (tennis serve and smash, racquetball ceiling shot, badminton overhead clear and smash) and when you reach up as high as possible (basketball rebounding, volleyball spike, catching fly balls).
Important Facts to Know
- The usual range of motion in this exercise is not great. The maximum appears to be 25-45 degrees on one side. Therefore, if you are not extremely flexible and you find yourself going through a range of motion greater than 45 degrees, you are most likely moving your hips or and rotating the shoulders to increase the range of motion.
- The quadratus lumborum is a major muscle involved in this movement because lateral flexion is its only action. Development of this muscle is needed for lateral stability of the spine and in preventing the spine from curving to the left or right, a condition known as scoliosis. Because the quadratus lumborum is a deep muscle, it cannot be felt or seen, but it is critical for a safe and pain-free lower back.