Sean Fyfe continues his take on postural fundamentals
Last month in Sports Injury Bulletin (SIB69, May 2007), we took an in-depth look at why the pelvic tilt is such a fundamental movement for sports therapists to understand and their clients to be able to execute correctly. My focus in that article was on the teaching and training of anterior and posterior tilt, as essential preparation for an athlete to be able to identify and hold neutral spine and achieve effective core stability.
Two of the most common postures that can give rise to injury and dysfunction are of course directly linked to an exaggerated pelvic tilt. Lordosis, which produces a pronounced hollowing of the low back, is the result of an overly anteriorly tilted pelvis; and flatback posture describes an overly posteriorly tilted pelvis (see Fig 1 below). In this follow-up article, I take a broader look at posture in general and a third very common aberrant postural presentation: the sway back.
What is good posture?
The positioning of the pelvis (direction and degree of pelvic tilt) is one of the key characteristics that determine our posture throughout life – and as such can cause us to develop pathologies and pain.
But what exactly is good posture – or for that matter, bad posture? In one helpful definition(1), posture is:
‘the alignment and positioning of the body in relation to gravity, centre of mass and base of support’.
As obvious as it may sound, we should be clear that we can have sitting posture, standing posture and, by extension, appropriate posture for any physical activity, be that running, cycling or rowing.
The aim of any posture is to achieve:
‘a state of musculoskeletal balance that protects the supporting structures of the body against injury or progressive deformity’(1).
This is achieved by the body being balanced by appropriate strength and length in its muscles – in effect, a ‘whole body’ force couple relationship. An optimal postural relationship will enable the body to achieve its maximal physiological and biomechanical efficiency.
In addition, good posture:
* minimises the stress and strain on joints and connective tissues
* provides shock absorption
* promotes the transfer of energy during movement.
Poor posture, by contrast, implies a ‘less efficient balance of body over its base of support, an alteration of normal arthrokinematics and therefore increased stress and strain on supporting structures’(1).
For sports injury practitioners, ‘good posture’ provides a fundamental point of reference in our work with athletes. We must be aware of the postural variations, be able to classify our clients within the relevant postural groups (normal/ideal, sway back, flatback and lordotic) and understand what their posture is likely to reveal about their areas of tightness and weakness.
If we are working with a fit and healthy athlete on performance enhancement and/or injury prevention, this information will help us to direct our physical goals. With injured clients, where we believe that posture has helped cause the problem, our under- standing will be able to help focus and direct our rehabilitation goals.
The sway back
Sway back posture occurs when the pelvis moves forwards and into a posterior tilt. Like the lordotic posture it produces an exaggerated extension of the low back, but unlike lordotic posture the key feature, viewed side on, is the forward positioning of the pelvis relative to the back and legs, as you can see from Fig 2 (right). The person with a sway back in effect rests on the strong anterior hip ligaments, rather than balanced muscles, for support.
Because the pelvis has moved forwards, the upper back sways backwards to counterbalance. This posture places the knees into hyperextension, hips into extension, lumbar spine, particularly the lower lumbar, into extension, the thoracolumbar junction and thoracic spine into flexion, the cervical spine into extension and the scapula into elevation. So it exaggerates the normal curves and joint positions of standing.
People with sway backs will usually find that the longer they have to stand, the more their posture deteriorates, and in general it gets worse towards the end of the day. This is because postural fatigue sets in: the stability muscle groups have tired.
The sway back posture generally causes the following musculoskeletal deficiencies:
* around the hips you see tight glutes and external rotators and weak hip flexors
* the lumbar spine extensors (erector spinae and quadratus lumborum) become tight and the lower abdominals are weak
* often this population will also demonstrate hypermobility through the lower lumbar area and stiffness through the thoracolumbar junction extending up into the thoracic spine
* the cervical spine erector spinae, upper trapezius, levator scapula and rhomboid muscles also become tight, which can limit the range of cervical flexion and lateral flexion
* the lower trapezius and deep neck flexor muscles are generally weak.
Table 1 above provides an overview of the relevant areas that require flexibility and strengthening exercises with sway back posture. It is worth noting that gluteus maximus and gluteus medius are also generally weak; but while strengthening them will improve their function, it won’t necessarily improve the individual’s standing posture.
So how does this affect the structural integrity of the musculoskeletal system? The most profound effect can be seen in the lumbar spine, where this posture causes an increase in the extension loading. How this manifests itself in terms of pathology depends on the client’s age. For example, a young fast-bowling cricketer will be susceptible to stress fractures, whereas a 50-year- old female golfer will be more likely to develop acute facet joint strains or chronic degeneration of the facet joints.
Sway back posture also increases the shearing effect (increased sliding movement of the joint between adjacent vertebrae) on the lumbar discs, which can lead to annular tears. Athletes with flatback posture will also be susceptible to disc injuries, in their case because of the increased loading through the anterior column of the spine and hence the increased compressive forces on the lower lumbar discs.
By causing tightness in certain ways, the sway back posture will increase the stresses on other parts of the system. The best example is the way that stiffness of the thoracolumbar junction and thoracic spine will place increased movement load on the lumbar spine. Other areas include the hip being more prone to anterior hip joint irritations, thoracic spine stiffness making a person more prone to thoracic disc injuries or costovertebral joint strains, and the cervical spine position causing facet joint compression, disc shearing/injury, upper quadrant muscle tension and upper limb neural tension.
The sway back posture can be an underlying cause of pathology among many sporting populations. In all three of the cases below, there is a relationship between the specific injury problem and the athletes’ underlying posture. Effective rehab therefore must address the posture deficits as well as the specific pathology.
Lumbar spine ache and posterior thigh pain in a teenage female distance runner
Her first symptom – an ache in her low back – appeared when she increased her training volume. As the symptoms progressed, she began to feel tightness at the back of her thigh, and when she did any speed work on the track, towards the end of the session she would get a grabbing sensation in her rear thigh.
A bone scan cleared her of any stress injury to the pars interarticularis (site of stress fractures in lumbar vertebrae). She demonstrated intense muscle spasm in the lumbar spine, tenderness over L5 and L4 vertebrae, an excessive range of lower lumbar exten- sion and pain at the end of range, limited lower lumbar flexion and increased neural tension with slump and straight leg raise tests.
The female runner is suffering from lower lumbar instability. The injury becomes more problematic when the stability system is challenged beyond its capabilities, either by increased distance or speed. As the stability system fails, she falls further into a sway posture which has increased her lower lumbar extension and joint translation. The bulk of her rehabilitation will involve strengthening the lower abdominals, hip flexors and glutes, and lengthening the lumbar spine extensors and hamstrings.
Anterior shoulder pain in a 40-year-old male social swimmer
His symptoms began one day during his twice weekly 1.5km swim. He felt a mild pain at the front of his shoulder in the last 500m. For the next month he continued to swim as usual, but the pain worsened to the point where he couldn’t complete the 1,500m.
On initial assessment he stood with a very sway back posture and a significant kyphosis through the thoracic spine. His shoulders were hunched (protracted scapular position) and he had poor muscle bulk in the lower trapezius. An MRI scan revealed a partial tear to the supraspinatus tendon and inflammation to the subacromial bursa. The increase in thoracic kyphosis (rounded upper back) and poor positioning and stabilisation of the scapula was causing a subacromial impingement.
His onset of symptoms had not needed any significant step-up or change in training: his postural problems were simply getting worse with age and the fact that he spent most of the day at work sitting. Rehabilitation consisted of rest while he retrained his posture, strength and flexibility in his upper back, shoulders, lumbar spine and pelvis.
Anterior hip and groin pain in a 60-year-old competitive lawn bowler
She had been having mild symptoms for more than a year, but these had increased in the past month and were starting to affect her performance. She was a right-handed bowler and was suffering pain in the left hip (the front leg during bowling).
Initial assessment revealed a sway back posture, decreased hip flexion to 80 degrees (against a desirable range of at least 120 degrees), no left hip internal rotation and the pain was reproduced during hip quadrant testing (hip flexion with adduction). An x-ray revealed mild osteoarthritis and a subsequent MRI showed degenerative changes to the anterior labrum.
We had to understand that these age-related changes could give her some ongoing problems and that she would need to manage the condition with a regular exercise routine. The priority was to improve internal rotation at the hip by loosening the deep hip external rotator muscles and posterior hip capsule, and thus increase the ability of the hip to move into flexion and adduction.
The long-term plan includes ongoing hip range of movement work but also addressing the sway back posture in terms of strength- ening and flexibility.