by Greg Morling
The vertebral column was originally designed to act as an arch. Take a look at the monkeys and gorillas who inspect us as we wander the zoo. When we became upright, the spine had to act as a weight – bearing column. Anthropologist from the University of Missouri, Carol Ward (2010), explains that to support our head and balance our weight directly over hip joints and lower limbs, the spine evolved as a series of S curves – a deep forward curve, a lordosis, in the lower back, and a backward curve , or kyphosis, in the upper back.’
This change didn’t happen overnight! It took place at least four million years ago, probably earlier.
This system of S curves is energetically efficient and effective for maintaining our balance and for bipediality. The ‘arch’ became the ‘curved column’ and brought with it associated problems, including a greater possibility of back pain. The pay-off was the ability to see threats from wild predators lurking in tall grass and the capacity to travel further distances with babies, food and other resources in our arms. We were also now able to reach hithero inaccessible fruits.
The lower region of the spinal column suffers from the pressure and oblique forces exerted on its curved structure by our upright posture. These forces are not so intensely present in our ancestral ape friends at the zoo.
There is only one muscle that joins the vertebral column to the legs; the iliopsoas. It is reasonable to assume then that this muscle would be intimately involved with the biomechanical changes that accompanied bipediality and the need for spinal curves.
Nik Bogduk (1997), the leading medical scientist in biomechanical discoveries relating to the iliopsoas provides evidence that iliopsoas, ‘plays only a small role in the action of the spine’, and goes on to discuss how much pressure derives from iliopsoas compression loads on the lumbar disc. These forces, particularly at the lower lumbar area are one major cause of back pain. There is certainly a downside to upright! Bogduk’s work also presents a possible challenge to the long held belief that the major role of the iliopsoas is hip flexion.
Considering that so much more balance is necessary to walk on two legs as opposed to four, stability of the spinal column provided by the iliopsoas could be considered a more important role for this muscle. This is one area that we explore in my practical workshops focused on the iliopsoas.
Tactile procedures aimed at giving these highly stressed iliopsoas connection points a ‘rest’ may lead to a more speedy recovery for an aching back.
I will be asking a friend of mine at the Sydney Taronga Zoo if his simian (monkey) charges have complained of back pain at all. There is a good chance that they have not and are probably ‘lucky monkeys’ unlike us bipeds! who rely so much on the integrity of our iliopsoas to keep us stable and free of the dreaded pain in the back .
References
Ackerman, J. (2006) Carol Ward quoted in ‘The Downside of Upright’ National Geographic July, 2006
Bogduk, N. (1997) Clinical anatomy of the lumbar spine and sacrum, 3rd edition Churchill Livingstone, Edinburgh