The posterior muscles of the core consist of two large sets of spinal muscles (one on each side of the spine) called the erector spinae, also known as the spinal erectors. These muscles perform all the heavy lifting your back can support. They are located along the segments of the spine and are called the iliocostalis, the longissimus, and the spinalis.
The iliocostalis is the outermost muscle that runs along the length of the spine. The longissimus is the middle muscle, and the spinal is is the innermost muscle. These spinal erectors stretch the length of the spine, starting at the lumbar vertebrae and running all the way up to the base of the skull. These muscles allow your spine to move into various positions including extension, flexion, and hyper-extension.The quadratus lumborum is also involved in twisting and lateral flexion.
This muscle lies just under the lumbar vertebrae, originating at the top of the pelvis and lumbar spinal segments, and then inserts on the lowest rib.
This muscle supports the spinal erectors in their job of stabilizing the spine.Finally, the multifidus muscle acts like a strut supporting abridge, which in this case supports the spinal column. This tiny but crucial stabilizing muscle helps alleviate pressure on the vertebral discs so that body weight can be distributed evenly along the spine.
Working with the more superficial muscles of the back (latissimus dorsi and trapezius, for example), keeps our spine straight while the deep muscle groups (such as the multifidus) contribute significantly to the stability of the spine. This is why so many of the exercises performed for core strength are “held” for a short period of time in order to improve muscle endurance, an important component of core strength.
When selecting exercises to perform for your core, consider your particular objective, the equipment available, and the time you have to train.
Then, select the core exercise sequence that suits you best. Each core exercise and progressions are outlined in this section.
Keep in mind that for the exercises for the core muscles, it is not the number of repetitions and sets you perform that is important, but how well and precise you perform them. Be precise and accurate to the best of your ability when working the muscles of the core. These muscles respond to subtle, low-intensity, long-duration movements and movement patterns, so be sure to do each movement and pattern well.