The Critical Role of Development of the Transversus Abdominis in the Prevention and Treatment of Low Back Pain

The rising incidence and prevalence of low back pain constitutes a major public health issue in our society today, with widespread economic, physiologic, and psychological costs. In 2015, it was reported that 80% or more of us will suffer from low back pain at some point in our lifetimes [19, 15] and that at any one time 540 million people worldwide are affected by low back pain [6, 7]. It is now the most common cause of job-related disability and a main reason for lost time at work [2, 6, 7]. The causes of this modern epidemic are many, but the sedentary lifestyle of the modern working human—characterized by prolonged periods of sitting and a lack of exercise—is likely a major contributor [4]. It is known that prolonged sitting is detrimental to the maintenance of proper spinal alignment and stability, but mechanical loading of the spine during sitting and standing is still not well understood. A commonly cited 1970 study by Nachemson and Elfstrom found that with standing there is approximately 100-kg compression on the spinal discs and that with sitting these forces increase to approximately 140 kg and rise further to 185 kg with forward bending while seated [18]. Lifting an object from that forward seated position can increase those loads to 220 kg [16, 18]. We have also come to understand that prolonged sitting causes lumbar flexion, reversing normal lordosis and leading to increased compressive, static (segmental) loading over time [3]. Callaghan and McGill also found that sitting results in significantly higher compressive loads in the low back than standing does [3]. Spinal structure is designed to maintain upright posture, absorb shock, and accommodate bipedal gait through three normal curves: cervical lordosis, thoracic kyphosis, and lumbar lordosis. Spinal alignment also depends on stabilizing structures such as the facet joints, spinal ligaments, and the intervertebral discs, as well as the muscles that provide dynamic stability by absorbing the energy of loading the spine during activities. Similarly, many treatments are available to manage chronic low back pain, but nonpharmacologic methods such as exercise are strongly recommended as the initial approaches [21]. The core muscles, consisting of the trunk muscles from the diaphragm to the pelvic floor, provide critical dynamic stabilization for the lumbar spine. Included in this group are the muscles of the pelvic floor, the rectus abdominis, the internal and external obliques, and, most critically, the transversus abdominis, the deepest abdominal muscle. Posteriorly, the erector spinae muscles span multiple levels of the spine and provide for erect posture. The deepest compartment posteriorly consists of the multifidus muscles, which provide segmental stability to individual vertebrae and increase the stiffness of the spine during function [11, 20, 27]. The multifidus muscles work with the transversus abdominis and the pelvic floor muscles to form what is known as the anatomical girdle. These deep compartment muscles are most important to provide essential stability to the spine [10, 11, 20, 23–25]. There is a great deal of support for the concept that the deep compartment muscles are the most critical to stabilizing the lumbar spine segmentally during activity, preventing deleterious loading that can result in injury and pain [20, 27]. Mani et al. reported that muscle injury or fatigue or spinal joint or disc degeneration can compromise the stabilizing effects of the structures in the spine, resulting in shearing forces that can cause pain [15]. They showed that activation of the deep core structures by the abdominal drawing-in maneuver (ADIM) creates a co-contraction between the transversus abdominis and the multifidus, resulting in decreased pain and improved symmetry during walking in those with low back pain [15]. Chon and colleagues in 2010 found that core stabilization techniques involving the recruitment of the central core stabilizer, the transversus abdominis, are necessary for managing low back pain and that the abdominal drawing-in maneuver was more effective at activating the transversus abdominis than general core stabilization techniques [5]. In a comparison study, Bhadauria et al. found lumbar stabilization to be a more effective exercise than Pilates and dynamic strengthening for those with chronic low back pain because it improved transversus abdominis activation and also addressed the multifidus [1]. In my practice, I have found the cue that best recruits deep core stabilization is to “suck it in” from the navel and below. This maneuver is the same as the abdominal drawing-in maneuver, which Mani et al. defined as “an inward movement of the lower abdominal wall in which the patient is instructed to draw the umbilicus toward the spine while maintaining a normal lumbar lordotic curve along with relaxation of the more superficial musculature” [15]. In my experience, most people cannot relate to or visualize the term “draw in.” They can, however, relate to and visualize “suck it in”—almost everyone has sucked in the belly at one time or another. Regardless of the terminology used to describe it, the benefit of activating the transversus abdominis correctly is achieving a co-contraction with the deepest segmental spinal stabilizer, the multifidus. Patients who would most benefit from it include those who have chronic back pain, those who have had back or abdominal surgery and are cleared by the surgeon to begin strengthening, post-partum women, children or adolescents with scoliosis, athletes, or sedentary individuals. Those who may not benefit include patients who have had abdominal hernia repair, those with severe diastasis recti, or those with severe uncorrected abdominal hernia. Hodges and Richardson in 1996 [10] and Lamoth et al. in 2008 [13] demonstrated that intentional transversus abdominis contraction, while in the neutral spine position (normal backward curve), is associated with lumbar multifidus contraction to activate the anatomical girdle, which augments low back stability [9, 15]. Additionally, Soundararajan and Thankappan found that retraining the deep multifidus was more effective than traditional back exercises for decreasing pain and functional disability in people with chronic low back pain [25]. These principles apply equally to non-athletes and athletes alike. Training the core muscles to stabilize the spine and trunk is essential in all sports activities. Of critical importance is the transversus abdominis muscle, which contracts just after your brain has the initial thought for motion [10–12]. During athletic activity, which involves constant motion and change, the transversus abdominis plays a role in stabilizing not only the trunk but also the extremities. For example, when an athlete raises an arm to strike a ball as in the volleyball serve or spike, the transversus abdominis and multifidus muscles must contract to stabilize the athlete while kinetic energy is transmitted to the ball. Similarly, a soccer player preparing to kick or a tennis player preparing to serve needs a well-functioning, anatomical girdle to avoid undue strain and injury.