Low back pain is a common clinical condition, and U.S. survey data report that 75-80% of people in the U.S. will experience varying degrees of low back pain during their lifetime, and that low back pain is the number one cause of activity limitation in people under 45, the number two cause of outpatient visits (after the flu), the number five cause of hospitalization, the number three cause of surgical treatment, and has a similar incidence in men and women. . Therapeutic exercise has been very important and effective in treating low back pain and restoring muscle function. Traditional therapeutic exercises (e.g., yanfei, etc.) focus on training the muscle strength and endurance of the low back muscles, but some scholars believe that low back pain is mainly due to abnormalities in the motor control of the muscle groups responsible for spinal stability, not simply abnormalities in muscle strength and endurance, so traditional exercise training does not achieve good results. In recent years, a method of spinal segmental stability training based on retraining the motor control of the deep trunk muscles has been proposed, which has shown significant results in the relief of chronic persistent low back pain, the recovery of activities of daily living and the return to work. Stability training for normal people can change the movement pattern of the low back muscle groups, so that their motor control function can be improved and low back pain can be prevented. Stability mechanism I. Relationship between spinal stability and motor control In 1992, Panjabi, a famous biomechanics scholar, proposed that the system of maintaining the stability of the lumbar spine includes three aspects: ① passive support system, which is supported by bones, ligaments and fascia, including vertebrae, intervertebral discs, small joints and ligaments; ② active contraction system, which maintains the movement and stability of the lumbar spine through the contraction of muscular tissues, including the muscles and tendons around the spine muscles and tendons; ③) central nervous system-led motor control: the timing, sequence, and intensity of muscle contractions of the active system are controlled through sophisticated neural circuits to maintain the motion and stability of the lumbar spine. Maintaining spinal stability is the main goal of sports therapy for low back pain. hodges et al. pointed out that the lumbar spine itself is unstable and requires the support of the perispinal muscles in the active system to maintain the stability of the lumbar spine. The term core musculature has come to be widely used in the field of rehabilitation medicine and sports medicine. It refers to the muscle groups responsible for maintaining the stability of the spine, and according to their functions and properties, the core musculature can be divided into two major groups: the first group is the deep core musculature, also known as the local stability musculature, which includes the multifidus, transversus abdominis, diaphragm and pelvic floor muscles. Some of them are directly connected to the vertebral bodies and directly fix the adjacent vertebral bodies by muscle contraction, while others maintain the stability between the vertebral bodies and maintain the lumbar vertebrae in the median region by regulating the intra-abdominal pressure through the synergistic contraction of each muscle. Together with the sophisticated motor control of the nervous system, this muscle group is the first line of defense in maintaining the stability of the lumbar spine. The second group is the superficial core muscles, also known as the overall stabilizing muscles, including the rectus abdominis, internal oblique abdominis, external oblique abdominis, erector spinae, lumbar square and gluteal muscles, whose main function during contraction is to control the direction of motion of the spine and to produce a large action moment, so that they can counteract the external load applied to the trunk and maintain the posture of the entire spine. As research continues, scholars have focused on the deep core muscles, considering them to be fundamental and more important. 1, multi-cleft muscle: multi-cleft muscle starts from the back of the sacrum, the transverse process of the thoracolumbar vertebrae, and runs obliquely upward inward, the superficial part ends at the spinous process of 3-4 vertebrae above, the slightly deeper one ends at the spinous process of 2-3 vertebrae above, and the deepest muscle bundle is connected to the adjacent vertebrae above it, which is more developed in the lumbar region, and its role on the stability of the lumbar spine is particularly prominent. Liu Bangzhong et al. used rapid upper limb movements (forward flexion, back extension, and abduction) as factors causing sudden spinal imbalance to investigate the role of the multifidus muscle in lumbar spine stability. When the upper limb is flexed forward, the center of gravity shifts forward and the spine is subjected to the weight moment that causes it to flex. In posterior extension of the upper extremity, the spine is subjected to a weight moment that causes it to dorsiflex. The movement of the upper limb in both flexion and extension causes an imbalance of the spine in the sagittal plane. When the upper extremity is abducted, the spine is subjected to lateral bending moments that cause imbalance in the frontal plane. To counteract these disturbances, the trunk muscles respond quickly to maintain trunk balance. This study found that in normal subjects, the multifidus muscle contracted earlier than the longest muscle and the iliopsoas muscle in all three directions of upper limb movement, indicating that the multifidus muscle is the fastest and first of the paravertebral muscle groups to respond to sudden spinal imbalances and thus plays an important role in maintaining balance in both the sagittal and frontal planes of the lumbar spine. Its pre-contraction increases the tension and stability of 1-3 lumbar segments and reduces the displacement between lumbar segments, thus avoiding injury, thus playing a role in stabilizing and protecting the lumbar spine. In the above study, in the group of patients with chronic low back pain, the contraction of the multifidus muscle was almost simultaneous with the contraction of the longest muscle and the iliopsoas muscle during rapid movements of the upper limbs in three directions, and the contraction of the multifidus muscle was significantly delayed compared to normal subjects, indicating that patients with low back pain have reduced function of the multifidus muscle. In chronic low back pain patients, the delayed contraction of the multifidus muscle at the moment of sudden spinal imbalance (e.g., during rapid movement of the upper limbs) results in a decrease in contraction force and stability, causing excessive displacement of some segments of the lumbar spine, resulting in injury and low back pain. This in turn proves the important role of the multifidus in the stability of the lumbar spine. 2, transversus abdominis: the role of the abdominal muscle as an antagonist of the paravertebral muscle groups in the stability of the lumbar spine is also very important, congenital abdominal muscle hypoplasia patients can develop scoliosis due to the loss of sagittal balance. As research on the role of abdominal muscle stability continues, scholars have focused more attention on the study of the transversus abdominis muscle. The transversus abdominis is a deep abdominal muscle that starts from the medial surface of the 7th-12th ribs, the thoracolumbar fascia, the inner lip of the anterior iliac crest, and the lateral 1/3 of the groin, with muscle fibers migrating inward transversely to the tendon membrane and participating in the composition of the posterior sheath of the rectus abdominis muscle, ending at the white line. Although the transversus abdominis muscle is the thinnest of the abdominal muscles, its fibers encircle the abdomen and are connected to the transverse processes and spinous processes of each vertebral body by the thoracolumbar fascia, and its contraction increases the tension of the thoracolumbar fascia. The mechanism by which the transversus abdominis muscle increases the stability of the spine is: ① increase the intra-abdominal pressure, which enhances the tension of the lumbar vertebrae and reduces the pressure between the vertebrae, such as weight lifting, jumping and other trunk back extension exercises to maintain the stability of the lumbar vertebrae is mainly this mechanism; ② increase the tension of the thoracolumbar fascia attached to the spinous process and transverse process of the lumbar vertebrae, thus directly stabilizing the vertebrae. The posterior layer of the thoracolumbar fascia is mainly the latissimus dorsi fascia, which is attached to the spinous process and maintains the balance of the sagittal plane only; the middle layer of the thoracolumbar fascia is attached to the transverse process and can maintain the balance of the coronal and sagittal planes, such as maintaining the balance of the coronal and sagittal planes in movements such as lateral bending and weight lifting. The two mechanisms mentioned above, the former has a more diffuse point of action, while the latter is more limited, and the two act synergistically to maintain the balance of the lumbar spine. 3, diaphragm: when there is spinal instability diaphragm can not act directly on the spine, the role of the diaphragm to maintain the stability of the lumbar spine is mainly through the contraction of the diaphragm to reduce the displacement of the abdominal contents to the thoracic cavity, increasing the intra-abdominal pressure, so that the abdominal muscles maintain a circular hoop-like geometry, it increases the tension of the thoracolumbar fascia attached to the spinous process and transverse process of the lumbar spine, through the thoracolumbar fascia so as to achieve the role of stability. 4, pelvic floor muscles: pelvic floor muscles as the bottom of the trunk support the abdominal cavity and pelvic organs, when standing and sitting pelvic floor muscles will be tense contraction. Since it is the bottom of the abdominal cavity, the pelvic floor muscle will also have an effect on intra-abdominal pressure. Therefore, the pelvic floor muscle also has a stabilizing effect by changing intra-abdominal pressure, by a mechanism similar to that of the diaphragm. Through the above numerous studies we can find the important role of the deep core muscles, i.e., the local stabilizing muscles, in maintaining the stability of the lumbar spine, but they do not act independently and need to contract synergistically with each other to form a local stabilizing system in order to play their stabilizing role. Of course, the superficial core muscles, the overall stabilizing muscles, are equally important, and the overall stabilizing system is added to the local stabilizing system to achieve ultimate stability.