Vibration, Proprioception, and Low Back Stability

摘要

The National Institute of Occupational Safety and Health report 'Musculoskeletal disorders and workplace factors' lists vibration as one of the five physical workplace factors associated with low back disorders with whole body vibration increasing risk from 1.2 to 39.5 times. However, little had been done to examine the effect of vibration on low back neuromotor control. Such neuromotor control can be a factor in stabilization and injury avoidance in the lumbar spine. The goals of this research project were to assess the effects of muscle vibration on low back proprioception (the ability to sense posture) and dynamic response both during and after vibration exposure in order to examine this possible effect as well as to examine the role of sensory elements within the muscle in dynamic low back stabilization. This research investigated this using both a model of dynamic spine motion and an experimental study examining proprioception as a function of muscle vibration. In the model, changes in neuromotor response variables including decreased response gain, increased response threshold and increased response delay were all found to decrease the effective trunk stiffness, increasing the amount of trunk flexion that might be observed and possibly increasing the potential for injury. Experimentally, such an increased trunk flexion was observed both during and after exposure. Subjects were found to have a 16.1% greater torso flexion during exposure to paraspinal muscle vibration. Torso flexion remained significantly increased after vibration exposure relative to before exposure.