The Body System You Didn’t Know You Had

Growing up, many of you most likely learned about body systems. There is the cardiovascular system, which pumps blood and delivers vital nutrients throughout the body. There is the neurological system, which in a way is like a large computer and electrical system that controls activity of various organs. There is the musculoskeletal system, which allows us to move about in gravity. It is helpful to think of the body in this way, and it has helped develop experts in the body systems (cardiologists, neurologists, orthopedists, etc) who have extensive knowledge about how that particular system works and what problems tend to impact it. 

However, there are also limitations to thinking of the body as a bunch of independent systems. One limitation is the reality that our body doesn’t really function like that. No one told the nervous systems to stay away from the heart, or the heart to stay away from the muscles. We have discovered just in the last century the idea of the gut-brain axis, or how the microbial content of our gut can influence things like our mood. Our body systems overlap with and influence each other all the time. It can therefore be frustrating to see healthcare professionals who understand only one system but have minimal awareness of how other systems interact with it. 

In the late 1990’s, Stedman’s Medical Dictionary first defined movement as a body system. It was an odd idea, and few recognized this until a few years later, when physical therapist Shirley Sahrmann of Washington University in St. Louis suggested physical therapists lead the charge in further developing the idea of movement as a body system. It is still kind of an “out there” idea to think of movement as a body system in itself, as many think of it as a product of a body system (most people associate it with the musculoskeletal system). We are also very used to the body systems that we have. Could it be that we have an entire “system” of the body that has been there all along?

The history of body systems goes back to anatomy. Ancient Egyptians performing dissections and discovering how the body pumped blood, for example, would discover something and others would expand on that idea in later years. It therefore shouldn’t be a surprise that, as we find out more about how the body is interconnected, that it becomes more and more challenging to keep the systems separate and still be aware of all the crossover between them. 

Maybe because it was conceived of in the late 20th century, the “movement system” was developed to intentionally recognize that. Movement occurs in every bodily system. The heart is a muscle and blood moves through vessels, the nervous system moves impulses and chemicals move in the spaces between nerves, the endocrine system moves chemical messages throughout the body, and the integumentary system stretches and crinkles as our bodies move through space. 

One advantage of identifying the movement system as a bodily system is that it can draw attention to improving its performance in a more holistic way. Orthopedic surgeons might do a knee replacement surgery and think the work is done when the joint surfaces have been replaced and no major complications have come to pass. However, going through such a surgery strains movement in multiple bodily systems. As blood and inflammation surges to the area to begin the healing process, movement is occurring. Healing happens in the skin, the muscles, and the bones. The skin has to be able to maintain its elasticity if the knee is to bend and move well. The body is also moving less during this time. There is atrophy in the muscular system (and atrophy that most likely happened before surgery), there is swelling that begins to accumulate because of the lack of movement in the leg. Research has even shown other health problems like depression, sleep disorders, systemic conditions, and cardiovascular problems are all more common in the 2 years following a “minimally invasive” hip surgery.(1)

Throughout life, movement is an essential part of what gives us meaning. It allows us to have control over how we experience the world and our relationships with others. If we have independence and can move about how we like, we are called “able-bodied,” and people who cannot do that are sometimes called “disabled” and in some cultures are moved to places hidden away from public view. 

While identifying movement as a body system can seem “out there,” I personally think it is more reflective of the function of the body and provides an opportunity for us to think about the body in a more holistic way, to recognize how we can keep our body moving and make efforts to maximize its movement. It is a system that also ties nicely in to our experiences as inhabitants of this body and this world. As Vanda Scaravelli said, the famous yogi, “Movement is the song of the body.” Maybe by recognising that song, we can improve our ability to hear its sweet music. 

1. Rhon DI, Greenlee TA, Marchant BG, Sissel CD, Cook CE. Comorbidities in the first 2 years after arthroscopic hip surgery: substantial increases in mental health disorders, chronic pain, substance abuse and cardiometabolic conditions. Br J Sports Med. 2019;53(9):547-553. doi:10.1136/bjsports-2018-099294