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“Don’t bend your back whilst lifting”- is this the best advice?

I work as a vocational physiotherapist for Active Plus in Auckland, New Zealand, where I am involved in manual handling training and providing rehabilitation programmes to assist clients in their return to work following injury.  This is complemented by my work as a researcher at Auckland University of Technology investigating the biomechanics of the lumbar spine and the importance of lumbar posture during lifting.

Ergonomic advise to keep the back straight whilst lifting is commonplace in clinical and occupational settings. Yet ironically the research about optimal lumbar spine posture whilst lifting is limited and very few studies have examined functional lifting tasks. Furthermore ergonomic interventions have failed to reduce back pain in occupational settings (as seen in this recent post).

My research investigated the influence of lumbar posture on the activation of the back muscles and force generation capacity during the initiation of lifting a box from below knee level in healthy people aged 18-35 years old.

We found that, in contrast to popular belief, when the spine was fully flexed, more force could be produced compared to when lordotic, and the muscles were least recruited.  This may explain why people frequently use a flexed spine to lift, since it is very energy efficient due to the lower levels of muscle control.  In contrast, when the spine remains lordotic whilst lifting, it is very energy demanding and one cannot lift as much.

The key messages from this research are that we should tell our clients that it is not only necessary for their back to bend when lifting items from below knee level, it is normal and unavoidable.  Trying to keep your back as lordotic as possible is very energy demanding and an inefficient posture to use.

The next stage in our research is to see how people who have persistent back pain respond to the same lifting task.  I look forward to sharing new knowledge with you in the future.

(I would like to acknowledge Grant Mawston and Mark Boocock who have significantly contributed to this research)

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