Reliability of Methods for Determining the Vibration Threshold

Overview

It is known that whole-body vibration (TVV) has beneficial neuromuscular effects such as muscle strength increase. These beneficial effects are explained by the muscular reflex response induced by TVV. Reflex latency measurement is frequently used in clinical and neurophysiological research. The latency of the reflex response induced by TVV is defined as the period between the onset of the vibration stimulus and the onset point of the spike in the EMG signal. The current research aimed to determine whether the cumulative average method is reliable for estimating the EST.

This is an experimental study for method development; a self-controlled (single group) study. Ten healthy male or female subjects between the ages of 18-45 will be included in the study. After obtaining informed consent from the subjects, 30 Hz low amplitude (2 mm) vibration for 30 seconds will be applied on the PowerPlate Pro5 device to meet TVV. After three minutes of rest, two sets of TVV will be applied for test purposes. For the test TVV, vibration will be applied at 25, 30, 35, 40, 45, 50 Hz frequencies, each lasting 30 seconds, with low amplitude. Vibration stimuli detected by using an accelerometer fixed on the TVV platform will be recorded the Data acquisition (PowerLab data acquisition system (ADInstruments, Oxford, United Kingdom). Soleus EMG responses will be recorded using the superficial electrodes (Kendall Covidien). The sample rate for recordings will be 40KHz. Latency calculation with Cumulative Average Method: It will be done. An 80-500 Hz band-pass filter and full-wave rectification will be applied to EMG recordings. The peak of reflex responses (spike) will be marked with the help of LabChart7 (ver 7.3.7, ADInstruments, Oxford, United Kingdom). According to this marked point, the averaging process covered 75 ms of the vibration data preceding the trigger and 15 ms after for each vibration frequency separately. Then, the average of the five vibration frequencies will be calculated for the accelerometer recordings and EMG recordings. The point where the standard error is lowest in the accelerometer recordings will be determined as the "effective stimulation point".