By Professor Emeritus John Carlson, Co-Founder of getback
getback™ has a particular interest in a little-known, but very important back muscle: the Multifidus.
It’s safe to say that most people, or at least very few people, have heard of the Multifidus. This little-known muscle plays a vital role in back stability and the occurrence of back pain. We’ll go so far as to propose that there are very few pain-free people walking around with abnormal Multifidus muscles.
First things first: where is it?
The Multifidus is made up of many small, segmental muscles that run the entire length of the spine from the pelvis to the last vertebra of your neck. It is a deep back muscle attaching directly to the vertebral bones, predominantly situated under the larger muscles which produce major spinal movements.
What is the function of the Multifidus in the back and neck?
The Multifidus muscle is extremely active in almost all daily movements. The attachments of this muscle have some fibres travelling from just one vertebra to another and others connecting to two or three vertebrae, meaning the multifidus is primarily involved in small segmental movement stabilisation in the spine. The Multifidus plays a crucial role as a back stabiliser and it has been estimated to contribute two thirds of the total muscular stability being applied to the back.
Why is it so important?
Anatomical and research literature highlight the fact that the musculature surrounding and supporting the spinal column have very separate, but highly specific functions to produce safe functional movement.
The Multifidus produces very fine control and stabilising of the vertebrae and is recruited (turns on) before any of the superficial movement muscles, and as such prepares the vertebra to avoid unnecessary movement.
The Multifidus is active in every direction of movement to control stability, while the superficial muscles produce movement.
When the Multifidus is injured or goes ‘offline’ the superficial muscles attempt to act as controllers, mainly through compression, which creates flow-on problems to facet joints and ligaments. The massive impact of the Multifidus in providing muscular stability for the spine cannot not be underestimated.
The million dollar question… what specifically causes back pain?
Clinicians and researchers have postulated many and different apparent ‘causes’ of back pain, but to date finding one over-arching cause has proved elusive.
Studies on pain-free people have shown that many of the things you would expect to cause back pain are in fact present in those without pain. MRI (Magnetic Resonance Imaging) studies of people reporting no back pain have shown the presence of abnormal discs, while nerve studies have also found that people with no back pain showed evidence of nerve compression.
A black and white, definitive cause of back pain is problematic, as it would seem that there are many people with apparent ‘abnormalities’ who are asymptomatic (have no pain).
What does the Multifidus data tell us?
Initially it has been shown that asymptomatic patients who have had their Multifidus examined demonstrate very few abnormalities in this musculature. Conversely, the vast majority of research studies correlate atrophy (weakness and reduction in size) of the Multifidus with pain, poorer outcomes and functional problems.
Specific Ultrasound studies revealed the Multifidus to be smaller on one side of the back in patients with acute and sub-acute back pain, and specifically this wasting (decline) was noted on the same side as the patient’s pain. MRI Cross sectional images of chronic back pain patients have also shown the Multifidus to be smaller over a number of vertebral levels when comparing patients to healthy control subjects.
MRI tests reveal a correlation between Multifidus wasting and leg pain in chronic pain patients. Multifidus changes have also been seen in cases of disc herniation, vertebral instability, post surgery and in those with back pain in pregnancy.
Strengthening your Multifidus – the most important aspect in addressing your back pain
Biopsy studies of the deep Multifidus show that the predominant fibre composition is type 1 Aerobic. This tells us that these muscles are low level contraction, responsible for control and stabilisation, but not major movement of the spine. They are constantly ‘on’ and adjusting to spatial and temporal demand as posture is maintained.
This constant low level of contraction in the musculature to maintain ‘normal’ posture (the effects of office or sitting posture) results in continuous loading of Type 1 fibres. Continuous activation during low intensity, sustained tasks or increased demand (fatigue or extra effort) is projected to be a precursor of injury. Or, it can result in decreased blood flow or damage to these fibres, resulting in pain. These anatomical and functional changes have been observed in the Multifidus.
However, it has been shown that very specific exercises that isolate the Multifidus can increase the size and symmetry of the muscles and lead to improved recovery from back pain, as well as less frequent and less significant back pain episodes in the future.
Informed by these facts, getback designed rehabilitation programmes to address these specific movement and stabilisation requirements for the spine. Exercise with specific and targeted movements utilising the Multifidus have been shown to decrease spinal pain when we focus the initial rehabilitation phase on the deep spinal muscles by using slow, light resistance and re-establishing the neuromuscular coordination without the use of heavy weight resistance.
Once these deep muscles are producing smooth and controlled contractions, we progress to increase the range of pain free movement and then increase resistance to engage more of the superficial musculature.