en Physical Therapy Physical Therapy Original Research Original Research <p style="text-align:left"><strong>Background: </strong>Whole-Body Vibration Training (WBVT) is a novel neuromuscular training method that has been recently developed as a rehabilitation tool. The purpose of this study was to determine whether WBVT is effective on electromyographic activity of the muscles of the lower limbs in patients with knee osteoarthritis.<br> <strong>&nbsp; Methods: </strong>The study was designed as a single blinded randomized clinical trial (IRCT201601171637N5), 45 patients with knee osteoarthritis were randomly assigned to three groups; WBVT (n = 15) receiving 12 sessions vibration therapy, control group (n =15) doing two exercise in the home and placebo (n =15) doing exercise like WBVT group on-off vibration system. Electromyographic activities of vastus lateralis and vastus medialis, semitendinosus, gastrocnemius and soleus were evaluated pre and post intervention. The paired- samples t-test and ANOVA were applied respectively to determine the differences in each group and among the groups (P&le;0.05).<br> <strong>&nbsp; Results:</strong> The RMS value of vastus medialis in semi squat position in placebo group (p=0.024), vastus lateralis in SLR position in WBVT group (p=0.037), soleus in knee flexion in WBVT group (p=0.018), semitendinosus in knee flexion in WBVT group (p=0.007) and RMS response of Semitendinosus in ankle plantar flexion in control group (p=0.047) were revealed significant differences between the pre- and post- intervention<span dir="RTL">.</span> The ANOVA test confirmed the significant differences between the studied groups according to the EMG activity of vastus medialis in semi squat position (p=0.045), semitendinosus in semi squat position (p=0.046) and in plantar flexion position (p=0.015) and also soleus in plantar flexion position (p=0.003)<span dir="RTL">.</span><br> <strong>&nbsp; Conclusions:</strong> The findings of this study showed the beneficial effects of WBVT in the improvement of the muscles RMS values in the patients with knee OA especially muscles&#39; progression rates in a four-week period.&nbsp;<br> &nbsp;</p> Knee osteoarthritis, Whole body vibration training, Electromyography, Randomized clinical trial 718 727 http://mjiri.iums.ac.ir/browse.php?a_code=A-10-2444-1&slc_lang=en&sid=1 Ebrahim Abasi ebiabasi@yahoo.com 200319475328460034317 200319475328460034317 No Department of Physiotherapy, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Sadighe Kahrizi kahrizis@modares.ac.ir 200319475328460034318 200319475328460034318 Yes Department of Physiotherapy, Faculty of Medical Sciences, Tarbiat Modares University, Tehran, Iran. Mohammad Razi mrazi_md@yahoo.com 200319475328460034319 200319475328460034319 No Iran University of Medical Sciences, Tehran, Iran. Soghrat Faghihzadeh s.faghihzadeh@zums.ac.ir 200319475328460034320 200319475328460034320 No Department of Biostatistics, Zanjan University of Medical Sciences, Zanjan, Iran.