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Think Ergonomics - Sitting in Motion

Sitting in Motion

13 Dec 2016 Katrina James

Bodies require movement to keep them in good physical and mental condition. You may have heard the saying “use it or lose it”. Particularly as the body and mind age. Children are always on the move – ask any teacher. In school, children sit on specially moulded plastic child size chairs or on cushions or mats for story time. And so, as they grow into youth and then adults they do more sitting. In classrooms, in cars, on trains and in universities. As they move into the workplace – there is more sitting.

The first major body of research on the topic of sitting was carried out between 1947 and 1972. Jeremy Morris* studied drivers and conductors working on London buses, trams and trolleys. It was found that drivers suffered a greater incidence of heart disease at a younger age than conductors.

Over the previous five years there has been a lot of discussion, health research and marketing on the long term health impacts of sitting in the office-based workplace. My trajectory here is to raise the topic of sitting for those not sitting in a traditional desk and office chair. I speak for those sitting for long hours in a truck, overhead crane cabin, a forklift, an excavator or similar piece of large moving equipment. These men (and some women) work in manufacturing and mining. They make and bring goods to our towns and suburbs, build our cities and our roads. As well as sitting, these workers’ bodies have to contend with mechanical movement from the equipment they operate. This is referred to as vibration.

Sitting for long periods of time is not good for the human body. Research demonstrates that over time it leads to an increase risk of diabetes, heart disease and other chronic health problems. Literature readily available to the public** proves the potential benefits of office workers standing up and moving around every 30 minutes. The media is stating “sitting is the new smoking”. Millions of dollars of research and public policy are being spent on alternative styles of sitting. Creative designers are coming up with office layouts and equipment that encourages people to change their posture and walk while working in the office.

Who is paying attention to today’s heavy equipment operators and drivers?

Truck and transport drivers and operators in todays heavy vehicle and equipment industry spend can spend up to 90% of their shift sitting in the drivers seat. This places our 21st century heavy vehicle operators in the same risk category as office workers for time spent sitting. In addition to sitting time, the heavy vehicle driver’s body also has to contend with the silent partner of sitting – vibration.

In simple terms, vibration is a source of physical energy that can be transferred from the mechanical operation of equipment. The operator receives the energy transfer and experiences this as vibration. An example is a large grader working on unsealed and bumpy road to grade it. Vibration from mechanical operation and the up, down, backward and forwards movement of the equipment is passed through the upper thighs, buttocks and lower back via the drivers seat.

Vibration to the whole body is complex and the motion of vibration can occur at a number of different angles and frequencies. Different people are sensitive to different frequencies. The effect is often one of discomfort or nausea. At worst, irreparable damage to the spinal discs may occur resulting in chronic pain and disability. This happens by stealth over long periods of time. It may be months or years before the worker feels the effect such as low back pain and muscular stiffness.

When we think of people operating heavy trucks, earth moving equipment and overhead cranes – they are seen as tough, hard working men. But they have the same skeletal and muscular system as any of us. Their bodies are equally as vulnerable.

Equipment designs need to be more favourable to allow movement. I have seen designs in overhead crane cabins that allow the driver to alternate sitting and standing. Heavy vehicles and equipment fitted with air suspension seating and isolators can reduce the impact of vibration to the body. In-shift schedules can be designed to encourage body movement. A review of in-house operational requirements and delivery times, for warehouse and customers can offer flexibility in shift breaks. Workers can support each other by buddying up and reminding each other to get up and move, go for a walk during their breaks and rotating certain tasks.

Adults require a greater awareness of the long-term health benefits of moving the whole body every thirty minutes. For heavy vehicle operators this action would have the potential effect of reduced risk of health impacts from vibration, and sitting.

As an ergonomist I have worked with teams to achieve equipment design and in shift changes. Managers have reported back to me that the workers are happier and more productive.  A moving body is a happy body – a child knows this.

In my experience as an ergonomist, the issue of vibration is not always addressed. I have met heavy equipment drivers not understanding how injury has occurred. Puzzled employers have not been able to fathom how sitting and operating heavy equipment can result in back pain.

Vibration from operating heavy equipment, and its ensuing injuries to the body are insidious and silent. If you own or operate this type of equipment – stand up and listen to your body, or talk to your workers.  Think about what changes can be made to reduce the exposure to vibration to improve physical health, wellbeing and the bottom line of your business.

 

Katrina James
Think Ergonomics
June 2016

 

References:

* LONDON TRANSPORT WORKERS STUDY
Coronary heart disease and physical activity of work. (1953) Lancet 265, 1053-1057.
Study Category: The Cohort Studies (1947-1972)
Years: 1949 – 1952
Location: London, England
Principal Investigator: Morris, Jeremy

** Public Health Resources: