Whole-body Vibration Training on Muscle Strength and Brain-derived Neurotrophic Factor Levels in Elderly Woman With Knee Osteoarthritis: a Randomized Clinical Trial Study.

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.