Which muscles make up the core?
The first muscle that comes to most people’s mind is rectus abdominis which is the six-pack muscle of your stomach. However, there are several other abdominal muscles as well as muscles in your back that make up the core. When we look at the anatomy of our body, bones make up a large part of its structure. Our bones are like a frame to hold us up, much like the frame of a house. However, in the abdominal region, we only have our lumbar spine as our frame. The lumbar spine is a strong structure, however, it relies on the muscles around it for stability. This is why the core muscles are so important. The core is a big cylindrical shape of muscles which consist of:
- Rectus abdominis at the front
- Internal and external oblique at the sides
- Transverse abdominis which is the deepest abdominal muscle that wraps around the body like a corset.
- Multifidus and erector spinae at the back which attaches to each individual vertebrae
- The diaphragm at the top
- The pelvic floor muscles at the bottom
What is core stability?
Core stability includes both the local and global muscles of the core. Local muscles attach between the segments of the vertebrae and typically only cross one joint. The main function of local muscles is to compress the joint which it crosses to stabilize that joint. Global muscles are the bigger muscles that typically cross multiple joints and may attach directly to the spine or indirectly through the pelvis or rib cage. The main function of global muscles is to allow movement through the spine in multiple directions. When opposing global muscles contract simultaneously, they can also stabilise the lower back, however, because of their attachment across multiple joints, movement through the spine is reduced.
The local and global muscles of the core work together to create core stability. When we want to move our spine the local muscles stabilise the individual segments of the spine and the global muscles pull across multiple segments of the spine to create the movement. When we want to keep our back still, particularly when picking something up, both our global and local muscles contract across the multiple segments to keep the spine still while our arms or legs are moving. This is to prevent any movement of the spine when picking up heavy objects.
The diaphragm and pelvic floor muscles, which make up the top and bottom of the cylindrical core, can increase the pressure within our abdominal region to further create stability within the spine.
How does core stability relate to lower back pain?
When the local muscles of the core are weak there is no longer individual segmental stability in the spine. Therefore the spine has to rely on other structures for stability, such as ligaments, vertebral disc, connective tissue, or the global core muscles. These structures are not as good at stabilising the spine without the local muscles being involved and can often be stretched, strained, compressed or fatigued causing pain in the lower back.
Why do the local muscles of the core become weak?
“Use it or lose it”. This is the main principle for any muscle in our body. When we sit for long periods of time our core muscles switch off as our backs are being held up by the back of the chair. Furthermore, the less we move in our day to day activities the less work the core muscles have to do to stabilise the spine. If our core muscles are inactive or working at a reduced capacity, overtime the muscles will become weak. So when you decide to get back to the gym and lift a heavy weight after being inactive over the Christmas holidays your local core muscles will not be strong enough to stabilise your spine and will have to rely on the other structures mentioned above which could potentially cause injury to your lower back.
What exercises can I do to develop my core stability?
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