Posture & Biomechanics

Posture & Biomechanics 

Biomechanics is the scientific physics-based recognition of how our bodies work during rest and motion. It provides a method of analysing how a person runs, walks and sits, plus an intimate understanding of the altering bone, joint, muscle, and ligament positions during these activities. It also recognises the altering physical demands on nerves, arteries and veins during movement. Biomechanics help us explain structural imperfections and how they induce postural problems that impact everyday performance.

To take a simple example, when feet roll-in or pronate, there is a 'coupling' action as the legs internally rotate and visa-versa. When feet roll-out or supinate, legs externally rotate. This coupling effect does not stop at the hips, as the pelvis has been shown to tilt anteriorly with foot pronation. (1)

The rolling in and out of your feet are normal and necessary. This pronation supination assists our feet to adapt to changing surfaces, adsorb energy when contacting the ground and then transmit this energy to power during push-off.

These actions become abnormal only if they occur excessively or at the wrong time, as in the case of flat feet (pes planus) and highly arched feet (pes cavus). If this is the case, the repetitive nature of the foot and leg activity leads to overuse syndromes, such as shin splints (2) or achy tired legs and or bone adaptations such as osteoarthritis and may manifest in chronic symptoms as chronic lower back pain.

Muskuloskeletal injuries such as ankle sprains, torn ligaments, muscle tears and fractures can lead to altered biomechanics known as compensations.In some cases, an abnormal walk can lead to postural problems in the upper body, causing back, shoulder or neck pain, or even headaches.

In the case of developing children, structural imperfections recognised from an early age may help to reduce the chance of them suffering conditions experienced by their parents. For example, Intoeing, tippy-toe walking, knock knees, bowed legs and flat feet are all normal and necessary developmental milestones for a growing child. However, long-term consequences may occur if these milestones are delayed or missed.

The treatment of biomechanical problems is accomplished by first recognising postural and structural imperfections that are causing the body to compensate. Structural imperfections can be as subtle as a stiff big-toe joint (Hallux Limitus). This condition has been shown to alter biomechanics with compensation, resulting in excessive demand on structures under the arch, leg (3) and lower back (4, 5). Structural compensations such as: shin splints, sore feet, knees, hips or lower back, achy legs, arthritis and nerve and skin conditions.

Postural problems are often easily treated by first recognising and accommodating structural imperfections such as bowed legs and knocked knees. Rehabilitation focuses on improving soft tissue and joint motion and reducing the impacts of structural compensations. Walking and running retraining is essential for long term symptom resolution.

1. Barwick A, Smith J, Chuter V. The relationship between foot motion and lumbopelvic–hip function: A review of the literature. The foot. 2012;22(3):224-31.
2. Becker J, James S, Wayner R, Osternig L, Chou L-S. Biomechanical Factors Associated With Achilles Tendinopathy and Medial Tibial Stress Syndrome in Runners. The American Journal of Sports Medicine. 2017;45(11):2614-21.
3. Goldmann J-P, Brüggemann G-P. The potential of human toe flexor muscles to produce force. J Anat. 2012;221(2):187-94.
4. Dananberg HJ. Gait style as an etiology to chronic postural pain. Part I. Functional hallux limitus. J Am Podiatr Med Assoc. 1993;83(8):433-41.
5. Dananberg HJ. Gait style as an etiology to chronic postural pain. Part II. Postural compensatory process. J Am Podiatr Med Assoc. 1993;83(11):615-24.