## 5 Discussion  
The aim of the study is to analyze the acute effects of WBVE on the level of pain, functionality, and rating of perceived exertion in KOA individuals. The results suggest that one session of WBW exercises, with low frequency (5 Hz) and peak to peak displacement (2.5, 5.0, and 7.5 mm), was able to reduce the pain level and time taken to perform the TUG test and improve flexibility (functionality) without altering the subjective perception of the effort of these individuals. These results corroborate the findings of [PERSON] et al. [42], who showed that one session of WBV exercises with the same protocol, alone or in combination with auriculotherapy, decreased the pain of individuals with KOA. All participants that completed the protocol did not report adverse effects. During the protocol, participants did not use analgesics and NSAIDs. Moreover, it is worth mentioning that this study simultaneously analyzed the knee (left and right) in three views (anteorposterior projection with load, bipedal support and profile, and patella axial), the hip (anteorposterior projection), and the lumbosacral spine (anteorposterior projection and orthostatic profile)), which makes it relevant for the diagnosis and study of KOA. No significant differences were found in CG and WBVEG participants in the radiographic images. Considering nutritional monitoring, the practice of physical activity, and existing comorbidities, no differences were found between groups. Regarding the functional capacity of KOA individuals, the time required to perform the TUG test was improved in CG and WBVEG, but the performance of WBVE was better than CG and the performance in the ATF test was improved only in WBVEG. A study reported that the transmission of mechanical vibration to the body (during WBVE) stimulates the primary endings of the muscle spindles, activating \(\alpha\)-motor neurons, resulting in muscle contractions (tonic vibration reflex) [44]. Thus, the lower limbs are stimulated, and the improvement in strength, proprioception, and execution of functional movements [45; 46], as observed through the TUG test, could be possible. Moreover, changes in the viscoelastic properties after vibration could explain the improvement in the ATF test in WBVEG. [PERSON] et al. [47], using WBVE (vertical platform) for 2 to 3 days (from 8 to 10 Hz, 2 mm) reported no significant difference in functional performance (using the TUG test) in the range of motion of the knee joint and in the reduction of pain in the postoperative period after total knee arthroplasty. [PERSON] et al. [48] described that WBVE improved knee muscle strength, dynamic balance, and TUG-test performance in healthy adult females. This protocol was performed 3 times a week for 12 sessions, with 10 Hz and 4.5 mm, using a rotating-type WBV device. The level of pain was reduced only in WBVEG. The mechanisms involved in the reduction of pain can be explained according to vibration-induced sensory inhibition related to peripheral (a sensory inhibition would be linked to the gate control theory of pain) and central levels (justified by the stimulation of areas responsible for processing pain and vibrotactile sensations in the somatosensory cortex of the brain) [36; 49]. Pain is a cause of disability in individuals with KOA [1; 2; 3], and physical exercise is a very promising strategy to improve the symptoms of individuals affected by this disease [17; 18; 19; 20]. Studies suggest that WBV exercise may be an effective and safe form of exercise for this population [23; 43; 24]. However, scientific evidence is still scarce and inconclusive in this population due to the diversity of WBV exercise protocols. Regarding the pain level, the findings described in the current work are in line with [PERSON] et al. [50], who reported a decrease in pain and an improvement in the functionality of individuals with KOA after WBV. However, [PERSON] et al. [51] observed that WBV exercise improved function but not pain and joint stiffness in individuals with KOA. [PERSON] et al.