Introduction: Manual load lifting is the most common and most
stressful activity in manual handling of loads that imposes the highest
possible amount of biomechanical pressure on the body, particularly on the
spine. The present study was conducted to determine the prevalence of
musculoskeletal disorders and to estimate the mechanical force exerted on the
lower back in workers responsible for manual load lifting.
Material and Methods: The present
cross-sectional study was conducted on 120 workers responsible for manual load
lifting activities in 7 industrial settings in the city of Shiraz. The Nordic Musculoskeletal
Questionnaire (NMQ) was used for determining the prevalence of musculoskeletal
disorders and the 3DSSPP software was used to estimate the forces exerted on
the lower back during load lifting. Data were then analyzed in
SPSS-19.Findings: The results showed that lower back problems constitute the
most prevalent musculoskeletal disorder (68.3%). Evaluations conducted in
3DSSPP showed that in 17.5% of the cases, compressive forces, and in 10.8% of the
cases, shearing forces exerted on the L5-S1 disc were higher in the workers
than the permissible levels. There were no significant differences between the
rate of the prevalence of lower back pain at different levels of compressive
and shearing forces exerted on the disc (p>0/05).
Results: This finding might indicate the limitations of the
method used in this study for conducting a comprehensive assessment of loads
exerted on the spine.
Conclusion: The prevalence of musculoskeletal disorders, in particular
lower back pain, was estimated to be high among the subjects studied. The risk
levels of compressive and shearing forces exceeded the permissible amount in a
low percentage of the workers studied. The 3DSSPP software might have certain
limitations in the assessment of the pressure exerted on the spine.
