May 10, 2012
Where is Superman?

How many times have you tested prone extension/superman during an assessment? I’ve done it more often than I can count. But it wasn’t until I began thinking about the typical development of the inner and outer core muscles that I fully understood why so many of my clients have difficulty with this.
First let’s remember the sensory contribution: the vestibular system, which is stimulated by lifting the head off the support surface in prone, contributes to anti-gravity postural tone. Further, the Landau reaction is stimulated by vestibular input, neck proprioceptors and the visual system and is present after 4 months in typical development. These sensory inputs lay the foundation for the development of prone extension.
Next we need to understand that the Superman position, which typical infants display consistently somewhere around 5 months of age, is actually the culmination of skills. As alignment changes in the first months after birth, the inner core muscles become increasingly active in prone and supine and create spinal and pelvic stability prior to movement. The Posterior Oblique Synergist outer core muscle group (POS = contralateral latissimus dorsi and gluteus maximus) activates in prone in combination with the inner core muscle team. As soon as the POS activation begins, there is a counterbalance in anti-gravity flexion as the Anterior Oblique Synergist (contralateral obliques and adductors) activate. And as anti-gravity strength increases even further, babies can then activate these muscle groups external to weightbearing and lift their arms off the surface, demonstrating the superman position. This combination of vestibular input with inner core and outer core muscle activity creates anti-gravity function.
Children with movement challenges learn quickly in infancy that they can create postural stability (in the absence of good anti-gravity postural tone) by breath holding. This takes the inner core offline leaving the outer core muscles without an anchor and therefore the activation of the POS/AOS is significantly delayed and/or inefficient. This creates a domino effect creating poor anti-gravity strength and endurance and the inability to complete “superman”.
In treatment, our clients do not need to repeat the Superman activity in order to build anti-gravity function, they need to build the underlying sensory and motor skills by combining vestibular input with alignment, inner core activation and strengthening of outer core POS and AOS. With these components all working together, quality anti-gravity function emerges. And that’s when Superman flies through the air.
Thank you for sharing on Twitter. I certainly agree that repeating the Superman activity in order to build anti-gravity function is not necessary. Although I do use it occasionally as a simple assessment to determine overall extensor strength. I utilize activity ideas such as prone extension on the swing, prone extension with various yoga poses, scooterboard activities, etc to work on these muscle groups.
I am not all that familiar with the POS and AOS terminology. The way I am reading your blog post I am translating POS and AOS to extension with rotation and flexion with rotation – am I correct? I would love to hear further an example of an activity idea where you combine vestibular input with proper alignment, inner core activation and outer core strengthening so I can understand better.
Love your blog posts – always makes me think and analyze treatment techniques.
Thanks for the comment Margaret. The POS and AOS terminology are courtesy of Dianne Lee, a talented adult PT. These are synergies of muscles that are active in movement. Of course adult PTs use them when looking at gait but as paediatric therapists we see the use of these synergies as a child develops movement. Both synergies begin working bilaterally in development. The POS activates bilaterally in prone to create anti-gravity hip extension for an improved base of support with improved shoulder stability for prone propping. The AOS activates almost immediately bilaterally to balance the POS and create the influence of trunk flexion. This is how babies achieve the balanced anti-gravity extension and flexion in the trunk. As you noted when we begin to weight shift, the POS and AOS act unilaterally and create balanced trunk extension rotation and flexion rotation. Of course the contralateral synergists are working together (i.e. right POS and left AOS) in order to make this happen.
Understanding these synergists in developmental movement has added a lot to my understanding of development of prone extension and supine flexion. And there are 2 more which combine with central stability to create increased stability of the pelvis in upright, allowing for initiation of movement from the pelvic girdle rather than the upper trunk and thereby freeing the upper extremities for function. I feel another blog post coming on……
Thanks again for the opportunity to chat 🙂