Low-back disorders in agricultural tractor drivers exposed to whole-body vibration and postural stress

Vibration exposure has been known to have both negative and positive effects on human dynamics in a variety of clinical and occupational applications. Whole body vibration is known to be associated with low back pain and low back disorders [1]. It has been shown that whole body vibration and vibration of the lumbar musculature can result in loss of proprioceptive accuracy and delays in muscular response to sudden loading [24]. Conversely, vibration of the musculature has also been proposed as a means to improve the effects of training and exercise on strength and endurance [5–7]. Vibration has a number of known effects on proprioception in particular. These include kinesthetic illusions during vibration exposure [8] and altered proprioception post-vibration exposure [3, 9]. Understanding the neural pathways that contribute to these effects is important in better understanding the clinical and occupational implications of vibration exposure. Therefore, the objective of the current study was to examine brain activity using functional magnetic resonance imaging (fMRI) during a dynamic, proprioceptive task, both during and after vibration exposure in order to observe changes in activation that might contribute to these effects.

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The Comparisons of Whole Body Vibration Exposures and Supporting Musculature Loading between Single- and Multi-axial Suspension Seats during Agricultural Tractor Operation

Proceedings of the Human Factors and Ergonomics Society Annual Meeting ◽

10.1177/1541931213601212 ◽

2016 ◽

Vol 60 (1) ◽

pp. 923-927 ◽

Cited By ~ 1

Author(s):

Jeong Ho Kim ◽

Jack T Dennerlein ◽

Peter W Johnson

Keyword(s):

Muscle Activity ◽

Repeated Measures ◽

Whole Body Vibration ◽

Erector Spinae ◽

Whole Body ◽

Low Back ◽

Body Vibration ◽

Repeated Measures Design ◽

Industry Standard ◽

Agricultural Tractor

Due to rough terrain, agricultural tractor drivers are likely exposed to a high level of whole body vibration, especially impulsive shocks. These WBV exposures are often predominant in the fore-aft (x) or lateral (y) axis. However, the current industry standard seats are designed to reduce mainly vertical (z) axis WBV exposures, and therefore, may be less effective in reducing tractor drivers’ exposure to WBV. Therefore, in a repeated-measures design with 11 subjects, this study evaluated efficacy of a multi-axial (vertical + lateral) suspension seat in reducing WBV exposure and low back (erector spinae) muscle activity relative to an industry standard single-axial suspension seat. The results showed that while there was no difference in fore-aft (x) and vertical (z) axis WBV exposures between the seats, the multi-axial suspension seat had lower A(8) lateral (y) WBV exposures [median (interquartile range): 0.7 (0.41, 0.83) m/s2] and VDV(8) [13.5 (7.4, 16.4) m/s1.75] WBV exposures than the single-axial suspension seats [ A(8): 0.81 (0.48 0.93) m/s2; VDV(8): 13.5 (8.7, 18.5) m/s1.75] (p = 0.02 and 0.04, respectively). Low back muscle activity was also lower on the multi-axial suspension seats, however this difference was not significantly significant. These results indicate that mu the multi-axial suspension may have potential to reduce the WBV exposures and muscular loading on low back among agricultural vehicle operators.

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