There is potential in ergonomics – and probably any scientific discipline – that so much research is done, and so many articles are published, that key ones can get lost in the noise.
A paper I recently ‘rediscovered’ from Ergonomics in 2009 is a good example. An article By S M McGill, ‘Evolving Ergonomics?’ is a position paper on how back injury prevention for workers needs to evolve. The basic idea is that once we have gone as far as we can in fitting the task to the person (good ergonomics!), the remaining injury risk should / could be all but eliminated by fitting the person to the task. Specifically, by using detailed targeted training to change the way individuals move and lift.
The idea of this goes beyond simply training people to lift and move in a ‘standard safe’ way, and looks at more detailed effects of movements and postures. In this way it reinforces the more recent message from HSE that manual handling training should not be generic, but needs to get into the detail of the task-specifics and the work environments.
Recent HSE messages on manual handling training:
http://www.hse.gov.uk/msd/external-help.htm
Back to this paper…
The paper Evolving ergonomics? highlights some interesting findings from previous research:
- Heavy manual work between ages 15 and 20 being protective for future disc protrusion injuries, but predisposing towards nerve entrapment syndromes.
- The paradox that chronic back pain sufferers were found to show higher back strength, as a result of moving / lifting in ways that cause higher spine loading.
- Those with healthy backs tend to ‘utilise very low spine power’ – in other words if the spine loading is high, they have very little spine motion (bending and twisting). In effect what this is saying is that spine posture is key – keeping the spine in its natural neutral posture during lifting.
Some of these ideas of course are broadly familiar but it is always worth mentioning them. Particularly important is the idea that some manual handling is actually healthy for the back. Too little and the strength and technique fails to build, too much and natural vulnerabilities take greater effect. For each of us there is an optimal level of manual handling activity, and of course that will vary from person to person.
Reducing the risks – the way to safer lifting, carrying and push / pulling
This is not a comprehensive list, but key risk controls flagged up in Evolving ergonomics… Also, the heirarchy of control still needs a mention (as ever), that hazardous manual handling should in the first instance be eliminated where reasonably practicable. The reality is though, that despite best intentions, and an awareness of the risks, some potentially hazardous manual handling operations have to continue. The reason being that some businesses simply can’t operate without them.
- Avoid the end range of lumbar motion when under load (to reduce risk of disc damage). In other words don’t lift while severely stooped (or when arched backwards). Not much new there granted – but still a key risk variable.
- Avoid loading the spine after prolonged flexion (forward bending – or potentially sitting, which tends to cause spine flexion). The spine has a ‘biomechanical memory’ and takes time to return to full strength capability after sustained flexion. Suggested actions are task pacing taking this into account, and training workers to stand / walk for a short period prior to lifting. An example of a particular at-risk group in this are long-distance delivery drivers, who potentially sit for several hours then immediately start lifting or pushing / pulling loads without giving their spine a chance to recover full strength.
- Ensure abdominal wall is stiffened / braced before lifting. This pre-stresses the torso-spine system for stability.
- Hold loads close to reduce the reaction moment on the lower back. And when pushing and pulling aim for a posture that keeps the force direction vector in line with the spine. Keeping loads close is a key way to reduce strain on the back. HSE research shows that for every 10cm further away from the lower back a load is supported, there is a 20% increase in rates of lost time due to lower back injury. This is highly significant, for individuals all the way through to UK PLC.
- Especially avoid a twisting force while the spine is in a twisted posture. Each of these can be a risk in their own right, but combined they are a much greater concern. An example of a complex handling task where this combination is foreseeable is patient handling (especially in unassisted ‘rescue’ scenarios).
- Where possible transfer body momentum to the load, and use the loads momentum as much as possible during handling and transfer – but only up to a point where transferring momentum from body to load does not cause a ‘jerk’ i.e. a sudden spike in spine or joint loading.
Hopefully those are useful messages for anyone looking to manage manual handling risks. If you are getting reports of back injury or increases in sickness absence, or if you just want to make sure that the risks are as carefully managed as they should be, then please get in touch with us. Guildford Ergonomics provides consultancy and customised training in all aspects of manual handling and other aspects of musculoskeletal risk.
Further information
McGill, S (2009) Evolving ergonomics? Ergonomics. 52(1). Taylor & Francis.
L23 (2016 – rev. 4th edn.) Manual Handling – Manual Handling Operations Regulations 1992 – Guidance on Regulations. HSE Books. http://www.hse.gov.uk/pubns/books/l23.htm
MAC (Manual Handling Assessment Charts) – INDG383. HSE Books. http://www.hse.gov.uk/pubns/indg383.pdf
Risk Assessment of Pushing and Pulling (RAPP) tool – INDG478. HSE Books. http://www.hse.gov.uk/pubns/indg478.htm
Getting to grips with Manual Handling – INDG143. HSE Books. http://www.hse.gov.uk/pubns/INDG143.pdf