## 4 Discussion
It is important to note that in one of the high-quality studies [26], the results between the groups were similar, possibly due to the fact that the intervention group was characterized as a 'nonintensive' BF exercise group, since the whole process took 15 min in a single session. As a result, the intervention in both groups was very similar. In another experimental study, [PERSON] et al. [19] stated that PFM exercises with BF were effective in reducing urine loss and in increasing muscle strength. It has been supported that the increase in muscle strength reduces incontinence symptoms [41]. [PERSON] [42] examined the effectiveness of a PFM exercise program and supported that after the pad test and the urine loss test, there was a correlation between increased strength and decreased urine loss. On the other hand, [PERSON] et al. [32] supported that urine loss was not related to muscle strength. It is, therefore, possible that the main clinical benefit in patients with SUI was related to the improvement in the perception of contractions and not necessarily to the improvement in muscle strength. With the application of BF, females improved their body awareness, structural support of the pelvic organs and also reached faster automatic muscle contractions [32]. The biofeedback informed women about their muscle condition, providing them with instant information by giving feedback usually via a screen [43]. By watching physiological data moving towards the right direction, patients felt confidence and satisfaction, thus, enhancing this movement even more [13]. In the systematic review of [PERSON] et al. [21], the studies mostly found that the volume of urine loss significantly reduced in the BF group compared to the other groups. However, only women with SUI were included compared to this current systematic review, where SUI, MUI and UUI were included. Therefore, the inclusion of only women with SUI could have affected the results because it is known that these women have greater improvements than other types of urinary incontinence [44]. In contrast, one of the RCTs [31] included in the current review mostly consisted of women with MUI and showed that between the BF and non-BF group, there was no significant difference concerning the severity of incontinence. Additionally, [PERSON] et al. [36] supported that the addition of BF reduced urine loss during exercise. Concerning muscle endurance, two included studies [29; 32] showed that the BF group had significantly better results in comparison to the non-BF group, whereas one showed that there was no significant deference between the BF and non-BF groups [31]. In agreement with the significant improvement were the results from [PERSON] et al. 's [36] study, who found that PFM exercises with BF improved endurance. In regard to muscle function, in both the BF and non-BF groups, there was a statistically significant improvement (compared to the baseline), but across-group comparison results were similar [30]. In agreement with this was also another study [45]. PFM exercise on a dysfunctional pelvic floor was shown to be attributed to the improvement of structural support, prolonging activation time and enhancing precontractions, which, as a result, might have decreased or prevented urine leakage [46; 47]. The purpose of BF is to improve voluntary motor function, promoting neuroplasticity or activating functional neural regeneration mechanisms of the central nervous system by exposing them to new demands. This neuroplasticity process may assist people in controlling and in monitoring muscle activities and movements, enabling them to manipulate these physiological events during the activity [48]. Quality of life had significant improvements in both groups, but between-group comparisons yielded similar results in most of the studies [24; 25; 26; 28; 29; 30]. For the parameter of social life in most studies, there was a significant improvement in both groups; however, in one study, the results were in favor of the BF group (\(p\) < 0.05) [28].