EMG analysis and vibration
for assessment of propioceptors functions
Carmelo Bosco Ph. D., D. U., D. Hon .C.
To evaluate the proprioceptors capacity to function properly several subjects who have been previously (at lest one year before) operated in one leg, were exposed to vertical sinusoidal
whole body vibration (WBV) for 60s. During the vibration treatment the EMGrms activity of leg extensor muscles leg extensor muscles (mm. vastus lateralis: LL (left) and LR (right) and vastus medialis: ML and MR) were simultaneously monitored in both normal and operated legs.
The subjects stand in semi-squat position (knee angle at 90°) on a vibration platform (Nemes-Bosco System), while the frequency of vibration was settled around 40 Hz for a total period of 60s (Figures 11 and 12). When the EMGrms of the post-operated leg was compared with the healthy one, remarkable higher activity could be observed in the postoperated leg during vibration treatment. A statistical analysis revealed that the EMGrms activity of the post-operated leg was significantly higher than the counterpart leg (Fig. 13).
Fig. 11 . Electromyografic activity (EMGrms ) recorded from leg extensor muscles of a male athlete (mm. vastus lateralis :LR and LL and medialis: MR and ML of both left and right legs ), before and during vibration treatment .During the vibration period higher EMG activity was noted in both legs compared to normal conditions. However a remarkable enhancement of the EMGrms was noted in the post-operated leg (VLR and VMR ) compered to healthy one
Since it is likely that during a surgery a severing of proprioecpetors may occurred, it is therefore tempted to suggest that the high EMG activity noted in the operated leg might be caused by the inappropriate function of propioceptors. It is likely that among the functional capacity of the propioceptors, is filtering and modulate the neural drive from central command. If the propioceptors were severed during surgery (27), this filter capacity of the neural drive could therefore be lost-resulting in hyperactivity during vibration treatment.
Although it is not easy task to find a proper explanation, these findings could be utilised to detect the function of propioceptors. It should be noted that 100% of the subjects studied (eighteen), demonstrated higher EMG activity in response to vibration in the muscles of the leg operated compered with the controlateral healthy leg. These findings suggested that before a rehabilitation programme can claim to be successful, the assessment of the muscle functions described only by the mechanical evaluation of the force or torque output is not physiologically enough. There is steel an inadequate and lack of specific evaluation technique that could allow the assessment of the impairment due to the proprioceptors inability to function properly or not.
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Fig. 12 . Electromyografic activity (EMGrms) recorded from leg extensor muscles of a female
athlete (mm. vastus lateralis: LR and LL and medialis: MR and ML of both left and right legs),
before and during vibration treatment. During the administration of vibration, higher EMG activity
was noted in both legs. However a remarkable enhancement of the EMGrms was noted in the postoperated leg (LR and MR), compared to healthy one.
Fig.13. Mean (±SE) of the electromyogram root-mean square (EMGrms) given as percentage of baseline (100 %) recorded from mm. vastus lateralis and medialis in both nonoperated (N) and operated (O) legs of eighteen subjects - before and during vibration treatment. No statistical significant difference was observed between N and O before vibration treatment (ns). But during vibration the O legs demonstrated statistical significant difference with the N legs, P<0,002; (Student's t-test for paired observations).
