**5.1 Pelvic floor muscle relaxation exercises and biofeedback**

Pelvic floor muscle exercises were first used in pediatric urology by Wennergren and Oberg, with the aim of developing the child's awareness of their function [40]. During the exercises, the child learns to contract and relax these muscles without activating auxiliary muscles (gluteal and hip adductors). In order to improve voluntary control, the exercises can be combined with different types of biofeedback, such as visual (observation of the abdomen in front of a mirror), tactile (palpation of the PFMs or *M. transversus abdominis*), uroflowmetry or electromyography.

Biofeedback was first used by Maizels et al. in 1979, who implemented the use of urodynamics devices in children with detrusor sphincter dyssynergia [41]. During urination, children observed EMG activity of the sphincter. Improvement was achieved in two of the three treated children.

Uroflowmetry biofeedback consists of the child observing the uroflowmetry curve while urinating. During voiding, the child is advised to make sure that the curve is bell-shaped. Kjolseth examined the efficacy of uroflowmetry biofeedback in 32 children with DV [42]. The number of applied sessions was 1-9, while 47% of children required 4-5 sessions. Cure was achieved in 50% of children, improvement in 8 children, and 7 children were unchanged. The uroflowmetry curve was completely normalized in 55% of children. It has been shown that this type of biofeedback requires a smaller number of sessions compared to EMG biofeedback and leads to faster normalization of the act of urination [43].
