Occupational vibration exposure is a known risk factor for low back disorders. While past research has investigated issues such as transmission of vibration, the means by which vibration might result in low back pain is still not well understood. A possible mechanism by which vibration might result in low back injury is by a disruption of the proprioceptive system leading to decreased spinal stability and increased susceptibility to injury. Vibration has been shown in the past to alter several measures of proprioception in the joints of the extremities. These alterations change with the frequency of the vibration and last after the vibration has been withdrawn. However, these changes in proprioception have yet to be thoroughly investigated in the low back.
The aims of this research are to begin to investigate the effects of vibration on proprioception in the low back and spinal stability. It is hypothesized that reposition sense error (one measure of proprioception) will increase with exposure to vibration. Further, it is expected that this increase will be different with different frequencies of vibration exposure. The temporal properties of these changes will be investigated. It is hypothesized that after removal of the vibration, the increased error will persist for some time before eventually returning to baseline. Finally, these changes in proprioception will be compared to changes in sudden load dynamics using a model of spinal dynamics in order to assess the effect of proprioception on spinal stability. This research is important to better understand what types of vibrations put a worker at risk, how these vibrations increase risk, and what may be done to reduce risk. For example, if it is found that proprioceptive changes last for 10 minutes after exposure, it may be prudent to recommend truck drivers and heavy equipment operators rest for 10 minutes before participating in heavy lifting activities. This work will provide the ground work for future research examining how proprioception is altered by occupational vibration exposure and how it affects the overall spinal stabilization.
