Low back pain (LBP) has been described as a ‘20th century medical disaster’ (Waddell, 1998) primarily because the cause of LBP in most cases is unknown. The escalating incidence of LBP in recent years has led to it being the most common cause of disability in young adults and responsible for 100 million days off work per year in the UK alone (Ehrlich & Khaltaev, 1999).
Amongst other things Spinal instability was one concept that emerged as a potentially important issue underlying back pain and thought to be directly responsible for 20-30% of all LBP episodes (Pope and Panjabi, 1985; O’Sullivan et at, 1997)
What is spinal instability?
The spinal stabilising system can be seen as three inter-related subsystems:
* the spinal column and ligaments providing passive stability;
* muscles surrounding the spine providing dynamic stability;
* the neural control unit coordinating the muscle response.
Instability, and hence LBP, may therefore be caused by a dysfunction in any of the three systems.
The role of the spinal musculature.
It is well recognised that the lumbar spine/ low back without any musculature is inherently unstable. If you were to place 10kg on the top of a spine with no muscles attached, the spinal column and ligaments would buckle (Crisco, 1989). This is considerably smaller than the estimated loads of 150Kg when muscles are attached and working
What are the spinal muscles?
The Lower back muscles can be categorised as local muscles / core muscles or global muscles. The local muscles provide the stability of the spine while the global muscles help to move it.
The local muscles to remember are the Multifidus and the transversus abdominis. The Multifidus muscles are very small muscles that run in between the vertebra of the spine and help support it from behind.
The transversus abdominis muscle is the deepest of all the abdominis muscle and acts as a corset like structure to provide the spinal stability from the front.
How do these muscles work?
These muscles are endurance muscles. They contract for long periods of time to offer stability to the lower part of your spine/back. A series of experiments conducted on these muscles revealed that the Brain would switch on these muscles milliseconds before any movement of the legs or arms occurred (Hodges and Richardson 1997a, 1997b, 1997c).
Therefore the muscles were activated before movement to make sure the spine is stable.
What happens to these muscles during low back pain?
The same scientists Hodges & Richardson (1998), took people with lower back pain and looked at the performance of their local stabilising muscles. They showed that while these muscles would activate 175 ms prior to movement regardless of movement direction in normal healthy people, in people with lower back pain they would not activate until after the commencement of movement.
They also found that these muscles were generally smaller in people who suffered from lower back pain and even smaller on the side of the pain.
How can physiotherapy improve the function of these muscles?
This growth in the popularity of “core strengthening” and “Clinical Pilates” in the health and fitness industry is built on the results of the clinical trials discussed. Physiotherapists have been instrumental in every step of this research and therefore the profession as a whole understands the need for spinal stabilisation exercises.
Many Gym instructors and fitness trainers claim to produce “core strengthening’ programs without understanding the reasons for it.
Physiotherapists are able to assess for spinal stability and develop a program for you. In more recent times physiotherapists have developed a specific type on Pilates called “clinical Pilates”. This focuses on small controlled movement around a stable spine to engage and strengthen the local stabilising muscles.
If you suffer from low back pain and you want to start some form of exercising – clinical Pilates is the place to start.