## 5 Discussion  
The current work evaluated the combined effect of various non-pharmacological interventions (AT, WBVE and combined AT and WBVE) on the quality of life in individuals with KOA. Due to the fact KOA is a degenerative disease, it leads to a progressive functional limitation that used to compromise quality of life [44]. The hypothesis of this study was that the combination of both interventions (WBVE and AT) would have additional benefits on the physical health domain of the quality of life as assessed by the WHOQOL-bref in KOA individuals. The results of the current study suggested that all interventions (alone or in combination) were safe and no side effects were reported. Despite this, non significant inter or intra-group differences were observed in the analyzed domains (physical, social, psychological and environmental) of the WHOQOL-bref. As reported, several limitations are common complaints that interfere with activities of daily living and recreation in people with KOA [8]. We can find in the literature improvements in physical function [25], pain levels and functionality [27] after WBVE; by contrast, in the current study, the physical domain remained stable after this intervention. One possible explanation to these discrepancies is related to differences in the intervention variables. Recent studies focused on the effects of WBVE intervention on daily physical functions in KOA individuals [45] used higher frequencies (35-40 Hz) than the ones used in the current study. Moreover, [PERSON] et al., also reported improvements in symptoms of osteoarthritis of the knee and functionality; however, no significant differences were in pain or quality of life using a frequency of 25-30 Hz [22]. In the same line, a meta-analysis from [PERSON] et al. focused on the effect of WBVE in individuals with knee osteoarthritis, authors reported decrements in pain and improvements in function but in most cases the frequency was higher to 25 Hz (range 25-40), only one study used frequencies between 12-14 Hz [46]. In this current investigation non-significant improvements in function was found. The duration of the protocol is another important parameter to be considered. The duration of the protocol in the present study is lower (five weeks) than the ones that used 8, 12 and 24 weeks [23; 24; 28]. The position of the participants on the VP may also plays a role on the vibration transmission and therefore on the effects of this type of training. In our study participants were seated on a chair that was in front of the VP. This position was previously used in [PERSON] et al., in which the individual was sat on a chair with flexion of the knees and the feet were on the VP base [19]. The importance of this position is to reduce the load and the impact on the knee joint, providing a pleasurable method and with a possible greater adherence in the practice of physical activity. However, this may have led to a decrease in the effect of vibration due to a decrease of the transmissibility of the mechanical vibration to the individual. In the current study, considering the physical domain (Figure 5A-C) and the environmental domain (Figure 8A-C) of the WHOQOL, both interventions (WBVE and/or AT) did not contribute to alter the physical conditions of the KOA individuals. These findings are in agreement with [PERSON] et al., [22]. These authors have evaluated several parameters, including the quality of life by means of the WOMAC scale in KOA individuals exposed to WBVE. They also verified no significant difference between the experimental groups in term of quality of life. [PERSON] et al., have also pointed out that the physical manifestations of KOA have direct impact on aspects of the welfare of the individuals, including social interactions, mental functioning, and sleep quality [8].