## 1 Introduction  
Knee osteoarthritis (KOA) is the most prevalent type of arthritis that leads to disability in the elderly, mainly due to pain [1; 2; 3]. Cartilage degradation with bone remodeling, joint space narrowing, formation of osteophytes, swelling, low muscle strength, joint inflammation, stiffness, and loss of joint function may be present in KOA patients [3; 4]. Neuromuscular function is relevant in the development and progression of KOA [5; 6] and, as [PERSON] et al. [7] reported, neuromuscular differences in muscle activity and amplitude. Surface electromyography (sEMG) is a noninvasive tool for detection of the electric potential resulting from the transmembrane current of muscle fibers (muscle excitation). It can be used to measure the muscle activity and might provide insight into neuromuscular responses to exercises, aging, and diseases such as KOA [8; 9]. [PERSON] et al. [8] showed an alteration in neuromuscular activation in individuals with KOA (male and female) compared to healthy individuals, suggesting compensation due to knee extensor muscle strength reduction. Most of the interventions included in neuromuscular rehabilitation programs are based on resistance exercises, promoting the improvement of the pain level and function response in patients with KOA [10]. However, many interventions can lead to symptom exacerbation and pain flares in this population [11]. Therefore, feasible interventions that can induce clinical benefits in patients with KOA have been evaluated in recent years, including whole-body vibration (WBV) [12; 13; 14; 15]. An umbrella review reported that moderate evidence supports the role of WBV as a viable clinical intervention for managing KOA, although more studies are still warranted [15]. In a crossover investigation, [PERSON] et al. [16] verified that WBV can prevent the loss of tibial articular cartilage thickness (determined by magnetic resonance image) after prolonged immobilization in healthy male individuals. Moreover, authors reported that mechanical vibration can lead to adaptations in muscle and bone [16; 17]. In rats, according to [PERSON] et al. [18], it is possible that the mechanical stimulation in the articular cartilage could release lubricin antibodies that are capable of inhibiting caspase-3 activity, preventing chondrocyte death. In consequence, mechanical stimulation could be a possible therapeutic treatment, as in osteoporosis, and mild physical activity could also be used as a therapeutic treatment for cartilage disease such as osteoarthritis [18]. Although WBV has shown importance in improving various parameters related to the joint [16; 18], it is relevant to consider some undesirable findings, such as the deleterious effect of prolonged vibration from off-road motorcycling on the elbow joint [19].  
The clinical benefits of WBV are attributed to the vibratory excitation of muscle spindles and increased motor unit synchronization [17; 20]. The importance of this intervention lies in the positive effects reported on muscle strength and flexibility and improvements in symptom severity (i.e., pain) in various populations [21; 22; 23; 24; 25; 26; 27]. Until now, only one study showed a decrease in pain level (assessed by the visual analogue scale) using sitting posture in an auxiliary chair with both feet placed on the vibrating platform (VP) [13]. Several authors [13; 28; 29] have suggested that this posture can reduce the load on the knee joint when compared to squat posture.  
The aim of this investigation is to analyze the short-term effectiveness of WBV on lower-limb functionality through examining the electromyographic activity of the vastus lateralis (VL) [30] muscle during the five-repetition chair stand test (5 CST). Therefore, the hypothesis was that the WBV can improve the functional mobility and the neuromuscular response of patients with KOA.