Muscles are the largest organ system in the body, accounting for approximately 50% of our body weight.  We have different ways of categorizing muscles: how they look, how they move, and where they’re located. We are going to focus on muscles that move voluntarily, which means we tell the muscles to move, as opposed to involuntary muscles, which automatically move on their own (like our heart and blood vessels). There are 641 muscles in the body – 340 pairs (meaning we have one on the right, and one on the left), and one unpaired (which is the transverse arytenoid for those who must know).

Back Pain

70% of lower back pain is diagnosed as idiopathic or non-specific[1], which means we are not sure what caused the pain. However, most investigators believe that sprains and strains of the soft tissue are the source of pain. Soft tissue refers to muscles, tendons, and ligaments. So it may be surprising that the emphasis in evaluating and treating lower back pain, neck pain, and shoulder pain, is on the spine and the nerves coming out of the spine. In fact, from 1997 to 2005, the prevalence of the diagnosis of spine-related issues has increased 100% while the diagnosis of strains and sprains of soft tissue has gone down by 40%[2].

This is generally attributed to the increase in the use of high-tech imaging studies, such as MRI and CT scans.  However, just because we have a clearer image of what’s going on inside of your body doesn’t mean that we have a clearer understanding of what’s causing your pain. More than 90% of lower spine MRIs exams in adults are abnormal[3]. Studies have found that up to 40% of people have herniated discs and as many as 70% have degenerated discs with no pain. If people can walk around with abnormal spines without pain, then this means that abnormalities in the spine aren’t always the cause of pain. Your diagnosis of a herniated disc, spinal stenosis, or spondylosisthesis may actually be unrelated to your source of pain.

Muscles are often ignored when it comes to diagnosing pain. I believe the reason is that we rarely evaluate muscles as a source of pain. We generally don’t learn about or understand how they work, what chemical changes take place inside, and how they produce pain (the pathophysiology). I would like to take the next few blogs to discuss how muscles contribute to your chronic pain.

[1] Deyo, RA., et al. Low Back Pain. NEJM. 2001; 344(5):363-370

[2] Martin, B., et al. Expenditures and health status among adults with back and neck problems. JAMA. 299(6):656-64, Feb 2008.

[3] Zimmerman, Robert D. “A Review of Utilization of Diagnostic Imaging in the Evaluation of Patients with Back Pain: The When and What of Back Pain Imaging.” Journal of Back and Musculoskeletal Rehabilitation 8 (1997): 125-33.