Impact of Isometric Contraction of Anterior Cervical Muscles on Cervical Lordosis
When we are born we have two primary curves which have already formed in our spine, the thoracic (mid-back) kyphosis (forward curve) and the sacral curve. It isn’t until we start moving around as infants that our secondary curves form, the cervical (neck) and lumbar (low back) lordosis (backwards curve). The cervical lordosis forms as a result of lifting the head and the lumbar curve forms as a result of walking. One of the biggest issues that is sometimes failed to mention is a straightened cervical curve. How a normal curve become abnormal is something that has been explored to provide more clarity.
Proper cervical curves in the sagittal plane have been shown to be an important clinical outcome of health. Patients with less cervical lordosis have statistically significant increases in neck, upper thoracic, and shoulder pain, as well as overall inferior health outcomes. As cervical lordosis decreases from normal, so does the increase risk of continuous abnormal stress and strain loads on the vertebrae and intervertebral discs (IVD) resulting in bone remodeling, arthritis, and IVD and ligament damage. It can also increase tensile stresses in the nervous system resulting in various neuromusculoskeletal conditions. Reduced cervical lordosis increases stress and strain variations of vascular tissues resulting in ischemia, reduced perfusion of the spinal cord and surrounding tissues, and nerve conduction failure.
A study was done to determine whether hypertonicity of anterior cervical muscles can have a structural impact on the cervical spine. The authors of the study investigated the impact of isometric contraction (contraction without joint movement) of anterior cervical muscles on cervical lordosis. They used 29 volunteers. They produced sustained isometric contraction of the anterior cervical muscles producing either anterior head translation (n=15) or anterior head flexion (n=14), and x-rays were taken. These x-rays were compared to resting neutral lateral cervical x-rays. Muscle contraction was verified by the use of a handheld dynamometer.
Results showed that gender and peak force were not associated with change in cervical lordosis. This study shows no evidence that hypertonicity, as seen in muscle spasms, of the muscles responsible for anterior head translation and anterior head flexion have a significant impact on cervical lordosis. Reference books and published papers claim that “cervical kyphosis and hypolordosis can be caused by muscle spasms or hypertonicity in the anterior cervical muscles that produce anterior head translation and anterior head flexion.” However, to date there have been no published data that show the impact of anterior cervical muscle spasms on the cervical curve. This study does not show evidence that hypertonicity of anterior cervical muscles elicited from anterior head translation and anterior head flexion have a significant impact on cervical spinal alignment.
Cervical spinal ligament injury, such as those associated with hyperflexion-hyperextension whiplash injuries, may contribute to cervical hypolordosis. Weaker, lax ligaments decrease cervical spine stability resulting in structural abnormalities. Cervical hypolordosis, kyphosis, or anterior head translation can create a cascade of weakened cervical ligaments and discs yielding further increased hypolordosis, kyphosis, or anterior head translation. The results of this study are in direct conflict with over fifty years of radiographic reports, physiological texts, and articles stating that the loss or reversing of the cervical lordosis are caused by cervical muscle spasms.
What next steps can be taken in order to improve the curve of the neck when it has straightened or become hypolordotic? Chiropractic BioPhyics is a technique that is designed to mirror image the curve. It provides a force that is put into the abnormal curve to try and restore it. The treatment schedule is intense but results are there to show that this is a viable mean to restore some of the curve. Age and the amount of degeneration plays a part in how much change can actually occur, but the results speak for themselves. Proper cervical lordosis is important to have in order to life a life without future health complications.
Dr. Cory T. O’Lear-Zebroski