IADMS New York 2002   [back to the Category]

Ultrasound Imaging of Trunk Stability Musculature at Work   [read the french version]

Author :   Craig Phillips, BAppSc, PT

Ultrasound Imaging of Trunk Stability Musculature at Work

Craig Phillips, BAppSc, PT
Dance Medicine Australia
Prahran, Victoria, Australia


Over the last 10 years there has been much interest in research on the mechanisms and training of trunk and spinal stability. Dancers are benefiting with the literature noting that the most common injuries for dancers are spinal and spinal related. Although the work focuses on training the control of the deeper layers of abdominal musculature it is proving to be a challenge as the activity of these muscles is not easy to identify.


There are 2 systems involved in establishing an effective trunk stability mechanism.

Firstly there are the deep or local stability muscles including transverses abdominus, the anterior pelvic floor, the posterior fascicles of psoas major, the diaphragm and deep lumbar multifidus. The task of these groups is to control shear and translation, through a number of mechanisms, at the segmental level in the mid range joint position. They need to act submaximally but constantly as a background to activity.

Secondly there are the global stabilizers which take the load of the trunk and limbs and control movement.. Much misconception has developed that all these muscles need to be “strengthened” and felt to be working. Unfortunately this is not the case. If working well and effectively the patient will “feel” very little in the way of specific muscle activity.

Control of these muscles occurs at submaximal levels with low perceived effort, hence the difficulty in “feeling” them working. An effective tool now being used in the clinic is Real Time Ultrasound which can visualize activity in the deep muscles and show faulty patterns of activation. Tests have been developed to show effective disassociation of the deep muscles from the global stabilizers and patterns of breathing.

These are the keys needed to ensure an effective stability pattern and examples of effective and ineffective activity will be demonstrated in this presentation.