In hunting and gathering cultures, alternating movement patterns was part of living and essential for health. This shift from dynamic movement to static or awkward positions is illustrated in Figure 1.
Figure 1. The shift from dynamic movement to immobility and near vision as illustrated by the Hadzabe men in Tanzania returning from a hunt to our modern immobilized work and pleasure positions (Reproduced by permission from Peper, Harvey & Faass, 2020).
Dynamic movement promotes blood and lymph circulation and reduces static pressures. At present times our work and leisure activities increase immobility and static positions as we predominantly have shifted to a sitting immobilized position. This significantly increases musculoskeletal discomfort, cardiovascular disease, diabetes etc. The importance of movement as a factor to enhance health is illustrated in the recent findings of 2110 middle aged participants who were followed up for ten years. Those who took approximately 7000 steps per day or more experienced significantly lower mortality rates compared with participants taking fewer than 7000 steps per day (Paluch et al., 2021). Just having the head forward while looking at the cellphone significantly increases the forces on the muscles holding the head up as illustrated in Figure 2.
Figure 2. The head-forward position puts as much as sixty pounds of pressure on the neck muscles and spine (reproduced by permission from Dr. Kenneth Hansaraj, 2014).
For background and recommendations on what how to reduce static positions, look at our book, TechStress-How technology is hijacking our lives, strategies for coping and pragmatic ergonomics. and the superb article, Static postures are harmful – dynamic postures at work are key to musculoskeletal health, published by the European Agency for Safety and Health at Work (EU-OSHA, Sept 16, 2021) and reproduced below.
Our bodies are built for movement – it’s a central part of maintaining a healthy musculoskeletal system and the less we move, the more chance we have of developing health issues including musculoskeletal disorders (MSDs), type 2 diabetes, cardiovascular disease, cancer and more. However, the negative effects of sedentary work can be mitigated by paying attention to the postures we adopt when we work.
Whether workers are standing or seated while working, maintaining a good ergonomic posture is essential when it comes to preventing MSDs. Poor or awkward postures put unnecessary strain on the musculoskeletal system and, over time, can cause the deterioration of muscle fibres and joints.
Poor or awkward postures include those which involve parts of the body not being in their natural position. More muscular effort is needed to maintain unnatural postures, which increases the energy used by the body and can cause fatigue, discomfort and pain. Unnatural postures also put strain on tendons, ligaments and nerves, which increases the risk of injury. For example, the risk of neck pain increases when the neck is rotated more than 45 degrees for more than 25% of the working day.
These postures, including slouching, rotation of the forearms, or prolonged periods of sitting or standing in the same spot, can cause pain in the lower back and upper limbs. The risk increases when combined with repetitive work, static muscle load, or the need to apply force or reach. And even natural or good postures maintained for any length of time become uncomfortable and eventually painful. Everyone has experienced stiffness after being in the same position for any length of time.
What do we mean by ‘good posture’?
For workers, especially those in sedentary jobs such as office work, factory work or driving, it is important to recognise and adopt good postures. A good posture should be comfortable and allow the joints to be naturally aligned. The segments of our body can be divided into three cross-sectional anatomical planes: the sagittal plane, which concerns bending forwards and backwards; the frontal plane, which concerns bending sideways; and finally the transverse plane, which refers to rotation or twisting of the body parts. A good posture is one that ensures that all three of these planes are set at neutral positions as much as possible, in that the worker is not leaning backwards, forwards or to any particular side, and their limbs and torso are not rotated or twisted. Adopting neutral postures will help to lessen the strain on the worker’s muscles, tendons and skeletal system, and reduces the risk of them causing or aggravating an MSD.
In practice, workers can consider the following checklist to ensure that they’re standing or sitting in a neutral position:
- Keep the neck vertical and the back in an upright position.
- Ensure the elbows are below the chest and avoid having to reach excessively.
- Keep the shoulders relaxed and use back and arm rests where possible and ensure that they are adjusted to the size and shape of the worker.
- Avoid rotating the forearms or excessively moving the wrists.
- Ensure that any work tools can be held comfortably, and that clothing doesn’t restrain or prevent movement.
- Allow room to comfortably move the legs and feet and avoid frequent kneeling or squatting.
- Ensure that long periods of standing or sitting in the same posture can be broken up.
Employers can assist workers in adopting good postures by communicating checklists such as this one, and by promoting physical activity where possible, encouraging the fair rotation of tasks between employees to avoid them consistently making repetitive movements, and ensuring that workers have the capacity to take regular breaks.
Why our next posture is the best posture
However, maintaining a good posture at all times is not enough to reduce the risk of MSDs, and can even be harmful. Static postures, even if ergonomic, are still a risk factor if over-used. Our body requires movement and variety, which is why the best approach is to use a variety of ergonomic postures in rotation, breaking up long periods of static working with stretching, exercise, and movement. This is known as adopting ‘dynamic positions’.
It is important not only for workers who spend much of their day seated, but also for workers who primarily stand – such as factory workers in assembly lines. In both cases, sitting and standing are not opposites. The opposite of both is movement. Changing postures between sitting and standing is not sufficient for any worker – the working environment must still offer ways of varying their postures and incorporating movement into their daily working routines. What’s more, if standing work cannot be avoided, workers do not need lots of space in order to adopt dynamic positions in a healthy way. Blood flow propulsion mechanisms can still work correctly even if the worker is only moving around in one square metre. However it is still the case that they should have a break after 30 minutes of standing.
Work should therefore not only facilitate good postures, but ensure that good, ergonomic postures are also dynamic. Switching between sitting, standing and moving while ensuring that the musculoskeletal frame is not under any unnecessary tension can help sedentary workers avoid the onset of MSDs and other health problems. For more information visit the priority area on sedentary work.
EU-OSHA. (September 16, 2021). Static postures are harmful – dynamic postures at work are key to musculoskeletal health. https://healthy-workplaces.eu/en/media-centre/news/static-postures-are-harmful-dynamic-postures-work-are-key-musculoskeletal-health?
Hansraj, K. K. (2014). Assessment of Stresses in the Cervical Spine Caused by Posture and Position of the Head. Surgical Technology International, 25, 277–79. https://pubmed.ncbi.nlm.nih.gov/25393825/
Paluch, A.E., Gabriel, K.P., Fulton, J.E., et al.(2021). Steps per Day and All-Cause Mortality in Middle-aged Adults in the Coronary Artery Risk Development in Young Adults Study. JAMA Netw Open, 4(9):e2124516. https://doi.org/10.1001/jamanetworkopen.2021.24516
Peper, E., Harvey, R. & Faass, N. (2020). TechStress-How Technology is Hijacking our Lives, Strategies for Coping and Pragmatic Ergonomics. Berkeley: North Atlantic books. https://www.penguinrandomhouse.com/books/232119/tech-stress-by-erik-peper-phd/