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The Multifidus muscle: why is it critical, and why does it falter?

Musculoskeletal disorders are the biggest cause of disability. Despite the billions spent, the problem is just getting worse. Latest medical guidelines strongly recommend exercise therapy as the first-line-treatment for musculoskeletal disorders instead of much more expensive surgeries.

By Professor Emeritus John Carlson,  Co-Founder of getback

getback™ treatment for back pain focuses on the role played by the spine’s deep stabilising muscles, particularly the multifidus. But why is the multifidus so prone to weakness and injury?

Why is the multifidus so critical to back stability?

Control of the lumbar (lower) spine and vertebral stability during movement, and while maintaining upright posture, are important components for avoiding low back pain and disability.

The multifidus muscles, running the length of the spine from the pelvis to the last vertebra of the neck, play a crucial role in back stability. These small but powerful deep muscles are attached directly to the vertebra, underneath larger muscles which produce major spinal movements.

Compared to other lumbar muscles, the multifidus has short muscle fibre but high cross-over areas. This structure allows the multifidus to produce stabilising forces over a small operating area (typically spanning two vertebra), and act as stabilisers rather than prime movers.

Research has identified reduced strength and endurance capacity in the lumbar/thoracic and cervical extensors and flexor muscles in patients with chronic back and neck pain. When strength and endurance are reducing in these muscles, the multifidus is required to be constantly ‘switched on’ to maintain and control spinal stability.

However, if the multifidus becomes overloaded, a lack of blood flow and increased metabolic demand can result in spasm and the muscle ‘switching off’ – a unique quality of this important muscle.

When the multifidus loses function and goes ‘offline’, the larger superficial muscles are called upon as stabilisers, a role for which they were not designed. The superficial muscles attempt to act as stabilisers mainly through compression, which creates flow-on problems to other areas including facet joints and ligaments.

The critical role of the multifidus in providing muscular stability for the spine and avoiding flow-on impacts cannot not be overestimated.

What factors are causing the multifidus muscles to falter more often?

multifidus

Patients with no back pain show very few abnormalities in the multifidus during examination, while the vast majority of research studies correlate atrophy (weakness and reduction in size) of the multifidus with pain and functional problems.

A number of studies have described multifidus atrophy and its replacement by fat after low back injury, a pathological process that is closely correlated with Low Back Pain (LBP).

As the multifidus is constantly called upon to maintain stability and posture, it is placed under demand while we move, stand and sit during daily activities. Our increasingly sedentary lifestyles put even more strain on our lower backs and necks as gravity acts to pull the spine forward – for example, when we spend many hours looking at screens.

Unless we are actively exercising our spinal muscles to be stronger, everyday issues such as dehydration, vibration during driving, poor sitting posture and inactivity predispose us to injure the spinal musculature.

Why is it difficult to rehabilitate the multifidus?

Optimal functioning of the spinal muscle system is important for control and protection of the spinal segments following injury. 

Even when painful symptoms are initially resolved, it has been shown that the deep musculature does not return to full function, increasing the likelihood of recurrent symptoms. In particular, if multifidus strength is still deficient, muscular conditions are vulnerable to another episode of back or neck pain.

Man and woman testing the getback devices

There is broad agreement about the need for reconditioning exercise in the treatment of chronic spinal pain. While there is little agreement on which exercise methods are most effective, the type of muscle work seems to be important: strength development in the deep spinal muscles.

The main issue with this approach is that the deep muscles are very difficult to isolate. In freestanding strength training the gluteal muscles (hip flexors) tend to ‘take over’ the movement, bypassing multifidus involvement.

Other floor exercises and gym machines can’t effectively isolate and safely and progressively strengthen the multifidus by staged overload.

At getback we use TGA registered Medical Devices which through research design and testing have created a rehabilitation system which is specific, targeted, measurable, valid and reliable.

Another difficult aspect in spinal rehabilitation is to address strength development in every movement plane of the spine. In many instances, injury arises through compound movements such as bending forward and rotating (for example, while digging and gardening).

In these everyday movements, ongoing functional strength is essential. The getback devices are designed to provide specific, targeted and isolated rehabilitation in all movement planes, including flexion and extension, lateral flexion and rotation.