Childbirth causes significant alterations of pelvic organ support, pelvic floor muscles (PFM) function and abdominal wall (1,2). However, there is a lack of consensus on which are the most appropriate PFM and AM (abdominal muscles) exercises in postpartum programs. The aim of this study was to investigate the immediate effect of three PFM and AM exercises on the displacement of bladder base (BB), differentiating between parous and nulliparous women using transperineal ultrasound (TPU). 
We hypothesized that there will be a disparate effect of the PFM and AM exercises on the displacement of the BB by type of exercise, and by group.

A convenience sample of 18 nulliparous women and 13 postpartum women participated in this cross-sectional study. The vertical and horizontal displacements of BB were assessed with TPU during three randomly ordered exercises recruiting PFM and AM. The protocol involved three exercises: A) Submaximal PFM + Deep AM exercise, B) PFM + Deep A+ axial spine elongation exercise, and C) Curl-up exercise (Figure 1).
Two-dimensional TPU was performed by placing a 3.5 MHz curved linear probe on the perineum in the sagittal plane. The vertical and horizontal displacements of BB were assessed using the standardized method described by Henemann et al 2014 (3) placing the BB mark 1 cm apart from BN. A Graphical User Interface on MATLAB software has been developed for aiding in measurement process (Figure 2). A repeated measures multi-factor ANOVA using Bonferroni adjustments to multiple comparisons was used to compare the differences of the displacement of BB among exercises, and between groups. Means with 95% CI are reported.

The BB was elevated during Submaximal PFM + deep AM and PFM + self-elongation, while descended during curl-up exercise (Figure 3), showing statistical differences among elevating and descending exercises in both groups (P<0.01). Submaximal PFM + deep AM exercise displaced significantly more cranially BB in postpartum comparing to nulliparous women (Figure 3). BB was displaced significantly backwards during curl-up exercise comparing to Submaximal PFM + deep AM in both groups. No statistical differences were found in the horizontal displacement of BB between groups (Figure 3).

Findings demonstrated which exercises were descending BB in postpartum wpmen comparing to nulliparous one, and which one elevated BB in postpartum. Further research is required to determine the long-term effect of those exercises in the position of BB.

We concluded that there were a disparate effect of the PFM and AM exercises on the displacement of the BB by type of exercise, and by group. Exercises recruiting submaximal PFM and deep AM provoked an elevating effect on BB in postpartum and nulliparous women, elevating significantly higher in postpartum women; meanwhile PFM and superficial AM contractions descended and moved backwards BB in both groups, descending significantly lower in postpartum women.

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