Houston Methodist. Leading Medicine

Lower Spine News

No Evidence Yet That Pushing/Pulling at Work is Linked with Low Back Pain

What causes low back pain at work? Is it the lifting? The pushing? The pulling? Researchers from Canada have published a report on the 2,766 studies they found on low back pain in the work setting. Type of occupational setting included various levels of manual labor. There were firefighters, nurses, salespersons, kitchen helpers, postal workers, shipbuilders, physicians, and steel mill workers, to name a few.

In theory, it makes sense that shearing forces are applied to the spine during pushing and pulling activities. Load and compression on the intervertebral discs occur. But are these forces enough to cause overload injuries to the low back area?

In this systematic review, all available evidence was gathered, analyzed, and summarized. The search for published data on the topic included electronic databases well-known and respected such as Medline, EMBASE, and CINAHL.

Only 13 of the 2,766 studies met the necessary standards to be included. And an evaluation of the methods used in those studies showed that only eight of the 13 were high-quality. The remaining five were so low in quality, the reported results couldn't be used.

What makes for a "good" or "high-quality" study? First, the authors of the study use statistical measures that are valid and have high methodological quality. That means the sample size (number of people enrolled in the study) has to be enough to be relevant.

In this case of looking at the effect of physical activity (pushing/pulling) on low back pain, it would be helpful if the task measured by each study was described quantitatively (how much load, how often, direction, duration).

And these factors should be examined in light of when and how the low back pain occurs. The result would be a measure called dose response (i.e., what type of load is linked with low back injury).

According to the results reported in the eight high-quality studies on this subject, there just isn't enough evidence to say that pushing/pulling activities on-the-job causes low back pain. Nurses pushing and pulling heavy hospital beds do suffer low back pain. But whether it was the pushing/pulling activity or something else remains unproven. Likewise for any of the other workers engaged in occupations studied.

The results of this systematic review show the need for high-quality studies using a prospective cohort design. Prospective cohort means the workers are studied on an ongoing basis rather than asked after they have suffered a back injury what factors were involved.

This type of design helps eliminate what's called recall bias. In other words, statistics gathered as the injuries occur are more accurate in detail (how, what, when) compared with asking workers weeks to months later what happened and how it happened.

In summary, there just isn't enough evidence from high-quality studies to confirm a link between pushing and pulling work-related activities and low back pain. These activities may be a risk factor for low back pain but until enough evidence from high-quality studies is presented, it remains an unanswered question.

Darren M. Roffey, PhD, et al. Causal Assessment of Occupational Pushing or Pulling and Low Back Pain: Results of a Systematic Review. In The Spine Journal. June 2010. Vol. 10. No. 6. Pp. 544-553.


*Disclaimer:* The information contained herein is compiled from a variety of sources. It may not be complete or timely. It does not cover all diseases, physical conditions, ailments or treatments. The information should NOT be used in place of visit with your healthcare provider, nor should you disregard the advice of your health care provider because of any information you read in this topic.
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