Whole-body Vibration Training on Functional Performance of the Elderly With Knee Osteoarthritis
Condition: Osteoarthritis of Knee
MeSH terms: Osteoarthritis; Osteoarthritis, Knee
Study type: Interventional

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.
    

Detailed 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.
    

Intervention name(s): Addition of whole-body vibration to squat training; Squat training
Intervention type(s): Other; Other
Intervention description(s): squatting exercises for 12 weeks, 3x/week
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: 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.
Masking: Single (Outcomes Assessor)
Primary purpose: Treatment
Keywords: Muscle strength; Squat; Brain derived neurotrophic factor; Osteoarthritis of knee; Whole-body vibration; Elderly