EFFECTS OF WHOLE BODY VIBRATION ON SPINAL PROPRIOCEPTION OF HEALTHY SUBJECTS AND PATIENTS WITH LOW BACK PAIN

Abstract

Low back pain (LBP) is a common health problem with a high recurrence
rate. Current treatments are not that effective. As patients with LBP are often
found to be proprioception impaired, new proprioception exercises are required.
Whole body vibration (WBV) stimulates proprioceptive receptors on the muscles,
causing an alternation in muscle recruitment and hence modifying the muscle
stiffness and joint stability. Its potential to improve muscle function and
proprioception has been shown in athletes. Sinusoidal alternative WBV was
shown to be able to relieve pain in patients with LBP after a long term
application. However, the underlying mechanism has not been investigated.
Another study has demonstrated that short term WBV had an immediate effect
on improving pelvic repositioning ability on normal individuals. As spinal
proprioception facilitates spine positioning and movement and computes selfcoordination
under both static and dynamic conditions, it is essential to
investigate the effect of WBV on lumbo-pelvic stability, coordination and
repositioning ability to justify whether WBV has a beneficial effect on spinal
proprioception. In this study, the immediate and carryover effect of a 5-min 18Hz
WBV on spinal proprioception were investigated.
The study was divided into two stages. In the first stage, twenty young
normal individuals were recruited and the effects of WBV in standing and seated
postures on spinal proprioception were determined and compared. In the second
stage, the effect of WBV on spinal proprioception was evaluated in eight
individuals with LBP, with age matched with those in the healthy group, in
seated posture. The results were compared with the healthy subjects receiving
WBV in seated posture. In addition to quantifying body alignment, repositioning
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ability of participants before and after WBV, postural stability and phasic
relationship between the lumbar and pelvis segments were investigated in terms
of maximum reaching distance and lumbo-pelvic coordination using Dynamical
Systems Theory approach. Assessments were conducted before, immediately
after, 30 minutes after and 1 hour after 5 minutes of WBV (18Hz, 6mm p-p
amplitude). Multivariate analysis of variance was used to study the changes of
each variable and LSD criterion was adopted for post-hoc comparisons.
In the first stage, it was shown that WBV in both standing and seated
posture had significant beneficial effect on maximum reaching distance, dynamic
lumbo-pelvic coordination and repositioning ability without significant group
difference. Significant carryover effect of WBV was also shown. In the second
stage, immediate improvement of postural control, lumbo-pelvic coordination
and repositioning ability were observed for the LBP group. However, the effect
seemed to be less long-lasting.
There were limitations in the study. The effect of vibration intensity and
learning effect have not been fully investigated. As analysis was limited to the
sagittal plane, the effect of WBV on spinal motor control in other planes was not
known.. In conclusion, 5 minutes of 18 Hz WBV was shown to have significant
positive effect on lumbo-pelvic stability, coordination and repositioning ability
without any apparent adverse effect in both normal and LBP individuals. The
effects were more apparent and long-lasting when WBV was applied to healthy
individuals than patients with LBP. Further clinical study on patients with LBP
undergoing similar or different WBV protocol is recommended to confirm its
clinical application on improving spinal proprioception.