An electromyogram-assisted free-dynamic lifting
model was used to quantify the patterns of complex spinal loads in subjects performing various lifting
To assess in vivo
the three-dimensional complex spinal loading
patterns associated with high and low risk lifting
conditions that matched those observed in industrial settings.
Summary of Background Data.
Combined loading on the spine has been implicated as a major risk factor in occupational low back disorders. However, there is a void in the literature regarding the role of these simultaneously occurring complex spinal loads during manual lifting
Eleven male subjects performed symmetric and asymmetric lifting
tasks with varying speed and weight. Reactive forces and moments at L5-S1 were determined through the use of electrogoniometers and a force plate. An electromyogram-assisted model provided the continuous patterns of three-dimensional spinal loads under these complex lifting
The results showed that complex dynamic motions similar to those observed in risky industrial tasks generated substantial levels of combined compressive and shear loads. In addition, higher loading rates were observed under these conditions. Unlike loading magnitudes, loading rate was a better indicator of dynamic loading because it incorporated both the duration and magnitude of net muscle forces contributing to total spinal loading during the lifting
Quantification of spinal combined motions and loading in vivo
has not been undertaken. This study provided a unified assessment of the effects of combined or coupled motions and moments in the internal loading of the spine. Dynamic lifting
conditions similar to those observed in risky industrial situations generated unique complex patterns of spinal loading, which have been implicated to pose a higher risk to the spinal structure. The higher predicted loading and loading rate during asymmetric lifting
conditions can be avoided by appropriate ergonomic workplace modifications.