Before we can begin a discussion on core stability, it is necessary to define what exactly is included when we refer to our “core muscles.” While this term may be commonly used, there is no one concrete definition--even within the exercise and rehabilitative field--and so addressing this ambiguity is critical.
When people mention core muscles, they are generally referring to muscles around the abdominal region—an understandable conclusion could then be drawn that when we refer to our “core”, we are talking about our abdominals. This is a group of muscles including rectus abdominus (our six-pack muscle) our internal and external obliques, and transverse abdominus that make up what is commonly referred to as the abdominal wall. According to this definition, it would make since that strengthening these muscles would allow them to work longer before they fatigue, resulting in an increase in what people may think of as “core stability.”
Similarly, there has been a second, widespread belief that there was really one muscle that needs to be trained for “core stability”; the transverse abdominis—one of the deeper muscles of the abdominal wall. This belief was born from studies showing patients with low back pain had a delayed activation of transfers abdominis. It was then concluded that this was the most important muscle to activate, and physicians began coaching the concept of abdominal hollowing—sucking in the stomach to achieve isolated activation of this muscle. Through this lens, our “core muscles” have a hierarchy of importance, with transverse abdominis as the most relevant muscle needed to stabilize our abdomen.
The Deep Stabilizing System
I propose a third definition, taken largely from the work of Dr. Pavel Kolar, his background in developmental kinesiology, and his system of Dynamic Neuromuscular Stabilization (DNS). Dr. Kolar describes a group of muscles that he refers to as the deep stabilizing system of the spine. These muscles include all of the muscles of the abdominal wall, the deep segmental stabilizers of our spine such as multifidus lumborum, our pelvic floor, and our diaphragm. While strength certainly plays a small role, the emphasis here is placed on the nervous systems’ ability synergize and control the activation of these muscles, allowing them to work together as a unit to provide a dynamic “foundation” of support for human movement. While such a system may sound complex, the activation of these muscles naturally occurs at the subconscious level through proper utilization of the diaphragm’s stabilizing function. It is the activation and synergy of this deep stabilizing system that allows an infant to gain the ability to lift their legs and head, roll, sit, crawl, and walk. We observe this system in adults as well, and frequently see it utilized in high level movers and athletes performing at the pinnacle of their respective sports.
Re-learning dynamic stabilization:
While we are all born with this diaphragmatic stabilization strategy, not all adults maintain access to these movement patterns. Injury, movement repetition, fatigue, and stress are all aspects of life we are subjected to. As our bodies adapt to each of these demands, we naturally fall into our own unique compensatory movement patterns. While these individualized movements are inherently benign, they can limit our movement options, restricting the variability of our movement strategies to accomplish a given task. This decrease in variability can lead to less optimized movement patterns, decreasing athletic performance.
In addition, due to a wide variety of factors, these limited movement patterns can become associated with threat by the nervous system and become painful—a common example of this painful association would be low back pain associated with bending forward. With more limited movement strategies, we can quickly run out of options to accomplish a task, resulting in a decrease in activity levels and inability to perform active hobbies or even regular daily routines without pain. In these circumstances we can re-introduce this deep stabilizing system of the spine to remind the brain how to active and maintain this dynamic stability to unlock different movement strategies, providing pain-free movement alternatives to remain active.