They might not get much attention, but the erector spinae muscles are the unsung heroes of the back. These are two groups of muscles which follow the spine and help the abdominals support the entire torso and maintain good posture. The erector spinae muscles are not single large muscles but rather groups of smaller muscles and tendons. There are two groups, one on either side of the spine. The erectors stretch from the tailbone to the top of the rib cage with the individual muscles attaching at various points along the way.
The most important function of the erector spinae muscles is to work with the abdominals to help stabilize the torso. Together the erectors and abdominals form what some athletes call the core or powerhouse of the body. These muscles are essential for good posture while standing or sitting. Good posture uses muscles the way they should be used and helps the whole body function.
Lower back injuries and chronic pain are frequently due to problems with the erector spinae muscles. People who spend long hours hunched over keyboards are particularly susceptible to weak erectors and chronic backaches. The muscles can also be easily damaged through improper use, such as lifting heavy objects by bending from the waist, putting too much strain on the back.
To prevent injury, the lower back should be trained like any other muscle. The best targeted exercise to focus on the area is hyperextensions. These are done most easily on a hyperextension bench by securing the ankles so the body is nearly perpendicular to the floor, lowering the torso to a 45-degree angle, and lifting the torso until straight without arching the back. Squats and dead lifts may also be good training for the lower back, although holding the core steady while lifting any free weights may help.
Another way to work on strengthening the erectors is to focus on them as part of a set. Many muscles in the body are designed to work in concert, such as the biceps and triceps or quadriceps and hamstrings. The erector spinae muscles function as a set with the abdominals, so activities which focus on the whole torso can also help. Yoga and Pilates are excellent for conditioning the core because both activities utilize the back and abdominals to keep the body stable and balanced while performing various poses and exercises. Yoga poses such as "camel" or "triangle," or Pilates positions such as "spine stretch forward" can help relieve tightness in the erectors and improve posture.