The Cinderella hypothesis aims to explain the link between low-level muscular activation to an elevated risk of developing chronic pain, including chronic pain now commonly experienced among computer/screen users.
You will recognise that pain. It starts as an ache, or a cramp, or numbness and just keeps getting worse, until one day you have a frozen shoulder, or your tension headaches are now migraines, or you’re having treatment for RSI or Carpel Tunnel Syndrome.
In 1991, Hägg coined the term Cinderella hypothesis when researching factors associated with the development of musculoskeletal disorders (MSD’s). It associates low-threshold motor units with Cinderella who was recruited early and left to do all the work. The theory hypothesises that with muscle activation, low-threshold motor units are always recruited. These stay activated until total muscular relaxation. In the long-run and due to lack of recovery time, metabolic overload at the membrane level may occur, resulting in degenerative processes that lead to cell damage, necrosis, and pain .
This framework is still one of the most recognised pathomechanistic theories (or mechanism by which a pathological condition occurs) underlying the development of MSD .
Especially Relevant to Computer/Screen Users
Muscles held in static, awkward (i.e. non-neutral) or extreme positions [3-5] create fixed, constrained postures with low levels of muscle exertion (static loads) . Discomfort or injury is believed to occur as a result of muscles being held in a contracted state, but which are not doing heavy work .
Computer work is characterised by low levels of muscle activity, especially of the trapezius muscles . Computer operators are required to maintain one mostly seated position for extended periods. Work tools and workstations also have uniform elements leading to other recurring postural issues including excessive wrist flexion/extension and ulnar/radial deviation, repetition of movements about the elbow and shoulders, and extended time exposure   . The need for precisely coordinated hand and eye movements reinforces the need to maintain a static work posture. “Visual information is presented on a screen, and the information is handled by manual input devices like the keyboard or mouse. All the equipment is stable in the same position on the table and therefore requires the worker to keep the same static posture during work” .
This is why your mini and microbreaks are so important!
Visser’s 2006 literature review notes the risk factors leading to functional changes accompanying upper extremity muscle disorders (UEMDs) included: sustained muscle activity, especially of type I (Cinderella) motor units, (maybe a primary cause of UEMDs) and that it seems plausible suboptimal blood flow plays a role in pathogenesis of UEMDs .
How to Rescue Cinderella
The point of this article is to support the development of the personal skills needed to reduce pain and chance of injury and increase comfort and productivity. The skills is simple, only requiring you to release tension, keep moving and return to a relaxed neutral work posture.
Roll – Reset – Relax
This skill is very important. It not only helps you switch off and relax the low-level muscle units, but it also helps you re-establish a Relaxed Neutral Work Posture. Simply
- Sit back in your chair
- Plant both feet flat on the floor
- Move your chin back, so you feel your ears are over your shoulders, which are over your hips
- Rest your arms
- Roll your shoulders a couple of times
- Take a deep breath, and consciously relax.
This Roll – Reset – Relax is a vital work skill! It is central to your ability to manage upper body discomfort. As we work, we build up tension in our neck and shoulders and the only way to release this tension is by doing big movements’ and consciously relaxing.
By doing this one action (ROLL, RESET, RELAX) every time you find yourself leaning forward, leaning on your elbow or working with tense shoulders, you can reduce the discomfort in your neck and shoulders by up to – 50% – just by MAKING THIS YOUR NEW HABIT
While the lines between work and leisure may be blurred, there is no line between the tools we use for work and to run our lives.
Become aware of the tension we hold in our shoulders and consciously relax. Think of your Roll – Reset – Relax while you wait for your coffee, stand in a queue, or get ready for bed.
Like any new healthy habit, it will take a while before this becomes automatic, but the benefits to your musculoskeletal comfort will be substantial.
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- Visser, B. and J.H. van Dieën, Pathophysiology of upper extremity muscle disorders. Journal of electromyography and kinesiology : official journal of the International Society of Electrophysiological Kinesiology, 2006. 16(1): p. 1–16.