Clinical Trial Details
— Status: Completed
Administrative data
| NCT number |
NCT03918291 |
| Other study ID # |
U1111-1231-3069 |
| Secondary ID |
046.08 |
| Status |
Completed |
| Phase |
N/A
|
| First received |
|
| Last updated |
|
| Start date |
October 28, 2008 |
| Est. completion date |
June 28, 2012 |
Study information
| Verified date |
April 2019 |
| Source |
Federal University of the Valleys of Jequitinhonha and Mucuri |
| Contact |
n/a |
| Is FDA regulated |
No |
| Health authority |
|
| Study type |
Interventional
|
Clinical Trial Summary
The present study evaluated the effects of adding whole body vibration to squat training on
the isometric quadriceps muscle strength, the plasma concentration of brain-derived
neurotrophic factor at rest in elderly woman with osteoarthritis of the knee. The eligible
patients were fifteen elderly women ≥ 60 years of age who had been diagnosed with
osteoarthritis of the knee. The intervention consisted of uninterrupted squatting exercises
for 12 weeks, a 3x/week. The exercise protocol was similar in both groups differed only in
the presence of vibration.
Description:
Ethical statement: This study was carried out in accordance with the recommendations of the
ethical principles for research involving humans (Resolution 196-96 of the National Health
Council of the Brazilian Ministry of Health) and Federal University of Jequitinhonha and
Mucuri Valleys Ethics Committee. All subjects gave written informed consent in accordance
with the Declaration of Helsinki. The protocol was approved by the Federal University of
Jequitinhonha and Mucuri Valleys Ethics Committee (protocol No. 046.08).
Design: This is a randomized, controlled trial in which the variables were assessed 24 h
before and 24 h after a 12-week training program. For the allocation of participants, a 1:1
ratio randomization was performed using opaque envelopes for allocation concealment. To
minimize the chance of bias, The investigators used the following methods: a) opaque, sealed
and serial-numbered envelopes; b) the envelopes were opened sequentially after the
participant name and details were written on the envelope; c) the envelopes were kept in a
locked and secure place. The allocation sequence was concealed from the researcher enrolling
and assessing participants. Only one researcher performing the randomization was aware of the
group assignment.
Subjects: The particpants were recruited through the physiotherapy clinic and through medical
referrals. To participate in the study, participants were required to meet the following
inclusion criteria: females older than 65 years of age; not using hormone replacement
therapy; diagnosed with OA in at least one knee in accordance with of the American College of
Rheumatology. The severity of the kOA was classified radiographically according to the
Kellgren and Lawrence scale (grades 0-4, with 0 being normal and 4 representing severe OA). A
Grade 2 classification (definite osteophytes and possible narrowing of joint space) was used
as a cutoff to determine knee OA. Further inclusion criteria included the following: no
recent knee injury; no walking aid requirement; and no rehabilitation procedures in the
previous three months. Participants were excluded if they had any orthopedic, neurological,
respiratory or acute cardiac diseases or if had any cognitive deficit as determined by the
Mini-Mental State Examination.
Of the 125 elderly people screened for eligibility, 15 elderly women fulfilled the criteria,
had blood sampling collected at rest (8:00 a.m.) and then participated in the IQMS test.
Thereafter, the participants were allocated to one of two groups: 1) the vibration group, in
which participants performed squat exercise training in association with WBV (VG; n=7); or 2)
the exercise group, in which participants performed squat exercise training without vibration
(EG; n=8).
Procedures: The clinical and demographic data were collected from the participants using an
evaluation chart. Prior to the initiation of the 12-week intervention program, a blood sample
was collected at 8:00 a.m. from the volunteers of all groups followed by the isometric
quadriceps muscle strength (IQMS) evaluation. At 24 h after the intervention period, the
volunteers of both groups were reassessed. These procedures were performed to avoid any
circadian rhythm effects on hormonal status and the performance of IQMS. The tests were
performed by an experienced examiner who was blind to the group allocation.
The intervention program consisted of performing squat exercise training with (VG) or without
(EG) whole body vibration, three times a week on alternate days.
Warm-up: Prior to each training session, the participants warmed-up on a stationary cycle at
70% of the predicted maximum heart rate for each subject's age and were monitored using a
Polar heart rate monitor (Polar F4, Kempele, Finland) for 10 minutes. Immediately afterwards,
the participants of the VG group were placed in a position with their feet 28 cm apart (14 cm
to the right and 14 cm to the left of the center of the vibration stimulus) and were ready to
begin the squat exercises on the vibratory platform, while the participants of the EG group
performed the same procedure without vibration.
Squat exercises: The intensity of squat exercise training was systematically augmented in the
vibration and exercise groups over the training period by increasing the number of
repetitions (6 x 20 seconds to 8 x 40 seconds) and reducing the resting time (40 to 25
seconds). During each exercise repetition, the examiner instructed the volunteer to perform 3
seconds of isometric flexion of the quadriceps at 60º and 3 seconds of isometric flexion of
the quadriceps at 10º. The 60º angle was measured in each volunteer using a universal
goniometer prior to initiating the exercise series, and a barrier was placed at the gluteal
region to limit the degree of flexion of the knee. The participants of both groups were
placed in position with their feet 28 cm apart.
Whole body vibration: For the participants in the VG group, a commercial model of a vibration
platform was used (FitVibe, GymnaUniphy NV, Bilzen, Belgium). In this group, acceleration was
also increased by varying the vibration frequency (35-40 Hz). The mechanical stimulation
parameters of the vibration consisted of the following: frequency of 35 to 40 Hz, an
amplitude of 4 mm and acceleration that ranged from 2.78 to 3.26 G. The platform provided a
vertical sinusoidal vibration. Prior to initiating data collection, the platform acceleration
values were verified using the Mega accelerometer (Acceleration Measuring Kit ZPP1-3D-147BC,
Southampton, United Kingdom).
To measure acceleration on the horizontal and vertical axes, two accelerometers (Acceleration
Measuring Kit ZPP1-3D-147BC, Southampton, United Kingdom) were fixed at a distance of 14 cm
from the center of platform vibration. The signal was amplified electronically and was
stored. This signal was obtained at a frequency of 1000 Hz and was sent for computer
analysis. Each accelerometer was calibrated using two calibration points and applying zero
and gravity, Earth's gravity is 1 G (9.81 m/s2). To obtain the true acceleration values of
the platform, the values of Earth's gravity were subtracted along the vertical axis from the
total signal received so that the acceleration of the platform would begin at 0 m/s2. The
data were transferred to a computer using the Megawin software program, and the mean and
maximum acceleration of each sample on each axis were analyzed using the Matlab software
program. Each frequency used was measured over 60 seconds. In the pilot study, interexaminer
reliability was found to be high, with a coefficient of variation of 1.05%.
The participants underwent training on the vibratory platform with barefoot to avoid any
damping effect due to different footwear. In addition, a predetermined distance from the feet
(14cm to the right and 14cm to the left of the vibration center of the platform) was set to
ensure that each of the lower limbs received the same amount of vibration stimulus. Moreover,
with the aim of maintaining control of the body's center of gravity behind the base of the
support, the positioning of the spine, arms, and head and the type of squat (simulating the
motion of sitting in a chair) were standardized.
Isometric quadriceps muscle strength (IQMS): The IQMS was evaluated by the maximal voluntary
isometric contraction of knee extensors (MVIC) measured using the load cell. For this
evaluation, the participant was positioned in a flexion-extension chair (Home Sport, Master
Top model, Belo Horizonte, Brazil) and assumed a sitting posture with a straight trunk and
the hips flexed at 90º. The limb to be tested was positioned at 60° of knee flexion (assessed
individually by goniometry of the knee), and the resistance lever was positioned on the
distal leg.
The load cell was properly calibrated and positioned near the leg extension perpendicular to
the ground for signal acquisition during the isometric muscle strength tests (Miotec -
Biomedical Equipment, Porto Alegre, Brazil). The load cell was connected to the software
MIOTOOL 400 that transmitted the isometric muscle strength values to a computer. The MVIC
test was performed for 6 seconds with 1 minute between sets and with repeating three sets per
leg.
Before the test, the participants warmed up for 10 minutes on a stationary bicycle (Stone
Fitness, 2001, Huntertown, United State), which stimulated the heart rate (HR) to 70% of the
estimated maximum HR by age, as measured with the use of the Polar heart monitors (Polar F4,
Kempele, Finland). This procedure was performed to reduce the risk of injury during testing.
The intra-class correlation coefficient (ICC) for IQMS was 0.98 (95% CI: 0.94-0.99).
Analysis of BDNF by ELISA: For plasma processing, 10-mL peripheral blood samples were
collected from the antecubital vein using aseptic techniques and heparin as an anticoagulant.
The blood was immediately centrifuged twice at 3,000 g for 10 min, and the plasma was kept
frozen at -70º C until assayed. Plasma BDNF levels were measured in duplicate using ELISA
kits for BDNF (BDNF DuoSet, R&D Systems) according to the manufacturer's instructions; the
detection limit was 10 pg/mL.
