Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT02886819 |
| Other study ID # |
BEAH FTR-11 |
| Secondary ID |
|
| Status |
Completed |
| Phase |
N/A
|
| First received |
August 29, 2016 |
| Last updated |
December 19, 2016 |
| Start date |
May 2016 |
| Est. completion date |
July 2016 |
Study information
| Verified date |
December 2016 |
| Source |
Bagcilar Training and Research Hospital |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
Turkey: Ministry of Health |
| Study type |
Interventional
|
Clinical Trial Summary
Aim: Hypothesis of this study was that WBV activates different receptors or reflex pathways
depend on vibration intensity. Aim of this study was to test this hypothesis.
Methods: This study was conducted on 11 healthy adults. WBV was applied at various
frequencies and amplitudes. The right soleus T-reflex latency was determined before and
during WBV. WBV-IMR latency of the right soleus was determined using two different vibration
intensity: weak vibration and powerful vibration. T-reflex latency and WBV-IMR latency were
determined by using cumulated average method.
Description:
Aim: Whole-body vibration (WBV) induces a reflex response in muscles. The physiological
mechanisms underlying this reflex have been explained by activating muscle spindles
(stretch-induced reflex) or osteocytes (bone myoregulation reflex). WBV-induced muscular
reflex (WBV-IMR) latency was reported to be significantly longer than latency of T-reflex as
a stretch-induced reflex or nearly equal to T-reflex latency in the literatures. Hypothesis
of this study was that WBV activates different receptors or reflex pathways depend on
vibration intensity. Aim of this study was to test this hypothesis.
Methods: 2.1. Participants
Eleven young, healthy and right hand dominant male adult volunteers were included in this
study. The mean age of the participants was 25.4 ± 4.7 years, mean body height was 176.5 ±
6.7 cm and mean body weight was 77.8 ± 13.8 kg. All volunteers gave written informed consent
to the experimental procedures, which were in accordance with the Declaration of Helsinki
and were approved by the local ethics committee (Yeditepe University Medical Faculty
Clinical Research Evaluation Committee, Istanbul; 2016/564 ).
2.2. Procedure Prior to the induction of WBV, control T-reflex recordings were elicited and
then the participants completed a 15-s trial WBV protocol to familiarize themselves with the
procedure. Following the control T-reflex recordings, the trial protocol and a 15-s rest,
the participants received three set of WBV and T-reflex stimuli during WBV. A weak vibration
was applied in the first set. In next sets, a moderate and strong vibration were applied,
respectively. Vibration characteristics of three sets was given in Table 1. A WBV set
consisted of four vibration periods, each lasting for 60 s, with 5-s rest intervals between
periods. Within each set, WBV frequencies of 25, 29, 33, and 37 Hz were delivered The
surface electromyography (SEMG) and accelerometer data were obtained while the participants
stood upright on the vibration platform with the knees in extension. The participants were
barefooted and stood directly on the vibration platform. The whole plate oscillated with a
linear movement upward and downward. Two WBV devices (Power-Plate®Pro5, PowerPlate®
International, Ltd. London, UK) were used in the present study. One of them was used for
applying the moderate and strong vibration. The other WBV device was modified to attenuate
vibration intensity and used for applying the weak vibration.
2.3. Data Recordings The recordings of both T-reflex and WBV-IMR were acquired using SEMG.
The Ag/AgCl electrodes (KENDALL®Covidien) with a disc radius of 10 mm were placed 20 mm
apart on the right soleus muscle belly on shaved skin that had been cleaned with alcohol in
accordance with the recommendations of the Surface ElectroMyoGraphy for the Non-Invasive
Assessment of Muscles (SENIAM) project (Hermens et al., 2000). The ground electrode was
placed on the lateral malleolus. The sampling frequency was selected as 10 kHz.
A very light (2.9 g) triaxial MEMS piezoaccelerometer (LIS344ALH, full-scale of ± 6 g,
linear accelerometer, ECOPACK®) was taped to the participant's right Achilles tendon to
determine the timing of the onset of the mechanical stimulus for the T-reflex and to measure
stroke intensity of reflex hammer to Achilles tendon (Achilles accelerometer). Similar
accelerometers fixed to the WBV platforms to determine the timing of the onset of the
mechanical stimulus for the WBV-IMR (platform accelerometers). Acceleration unit used in
this study was m/s2.
A custom-made reflex hammer tapped the right Achilles tendon just caudal to the
accelerometer with a force of about 19.6 N. Before vibration and in each vibration session,
the Achilles tendon was tapped ten times with approximately 3-s intervals between taps.
2.4.Data processing SEMG and accelerometer data were recorded using a PowerLAB® data
acquisition system (ADInstruments, Oxford, United Kingdom) and the data were analyzed
offline using the LabChart7® (ver 7.3.7, ADInstruments, Oxford, United Kingdom) software. A
sampling frequency of 10 kHz was used. All accelerometer recordings were filtered with
high-pass filter set at 5 Hz. All EMG recordings were filtered using a band pass filter from
60 to 500 Hz.
The maximum peak-to-peak (PPmax) amplitudes of T-reflex were determined for each vibration
session. The amplitude of WBV-IMR was expressed as the Root Mean Square (RMS). The PPmax
amplitude of T-reflex and RMS amplitude of WBV-IMR recorded during the strong WBV were used
to normalize of the PPmax amplitude of T-reflex and RMS amplitude of WBV-IMR recorded before
WBV or during weak and moderate WBV.
In the present study, reflex latency was defined as the time between the onset of the
mechanical stimulus and the onset of the EMG spike on the cumulated average trace, both of
which were determined using the cumulative average method, as previously described (Karacan
et al). The positive peaks of the rectified EMG data were used as a trigger to average the
accelerometer data and the rectified EMG data. The point on the cumulative average trace of
the platform accelerometer data where the standard error (SE) was the lowest was considered
the stimulus onset point. The point on the cumulative average trace of the rectified EMG
data where the SE was lowest was considered the point of onset for the EMG spike. The mean
height of young adult males in country (175 cm) was used to normalize of the T-reflex and
WBV-IMR latencies (Cidem et al).
2.5. Precautions for voluntary muscle contractions and motion artifacts Five measures were
taken: 1) the participants were asked to use the handles of the WBV device to secure their
balance. The sense of balance may impair during WBV. Therefore muscles may be activated to
restore balance during WBV, 2) Before WBV trials, participants were asked to relax and not
to make voluntary contractions in their lower extremity muscles. This instruction was
provided with verbal feedback given by the researcher who monitored the SEMG recordings from
the screen. If the RMS amplitude of EMG was lower than five microvolts during this
intruction, it was accepted that muscle relaxation was accomplished by participant, 3) a
trial protocol was applied to familiarize vibration, 4) all cables were carefully taped to
the skin to minimize motion artifacts, 5) all EMG recordings were filtered to avoid WBV
induced movement artifacts (Sebik et al., 2013).
2.6. Statistical analysis The normal distribution of the data was confirmed using the
Kolmogorov-Smirnov test. Continuous variables were summarized as arithmetic mean and
standard deviation (SD).
The paired sample t-test was used to analyze the statistical difference in the amplitude of
WBV-IMR between weak and moderate WBV. General linear model repeated measures test was used
to compare in the T-reflex latencies, WBV-IMR latencies or PPmax amplitude of T-reflex among
the sessions. The alpha (α) threshold was chosen as 0.05. The Bonferroni test was applied
for pair-wise comparisons (PostHoc analyses). Using a Bonferroni (a significance level for
each pair-wise comparisons is α/m, m is the number of pair-wise comparisons), results with a
p value ≤ 0.017 were considered significant. Confidence interval (CI), mean, and standard
error (SE) were calculated for all data. When comparing means of two data sets, if ±95% CI
of one data set included the mean of another data set, it was established that there is no
statistical difference between the means of two data sets. The data management software
package used was PASW statistics (formerly SPSS Statistics) for Windows.
