Pelvic floor anatomy changes over the course of the day [1]. Many women with pelvic floor disorders report a gradual increase in their symptoms as their workday progresses [2]. Certain modifiable occupational factors may exacerbate symptoms, such as body position, which increases or decreases the effect of gravity on the pelvic floor, and voicing, which modulates trunk pressure [3]. This preliminary study is original by measuring the effects of occupational position (sitting versus standing) and occupational vocal load (high versus low) on pelvic floor morphology over the course of a workday. The hypothesis is that the greatest reduction in pelvic floor muscle support will be during a standing + high vocal load workday and the least change in support will be during a sitting + low vocal load workday.

This is a within-subject/repeated measures pilot study. Pelvic floor muscle support is measured with 2D trans-perineal ultrasound in supine (hook lying) and standing immediately before and after a workday (~6 hours).  The women in this study are all asymptomatic in order to establish normative ranges. Each participant repeated this study for four days to meet the following work conditions: 1) mostly sitting + mostly quiet, 2) mostly sitting + mostly voicing, 3) mostly standing + mostly quiet, and 4) mostly standing + mostly voicing. The primary outcome of interest is the change in resting levator plate angle (LPA), both in supine and standing, over the course of each of the four workdays. LPA is measured by taking the angle between a line from the apex of the pubic symphysis to the anorectal angle and a horizontal reference line perpendicular to the apex of the pubic symphysis. Descriptive statistics are used to present the results.

To date, four women, ages 30-43, have completed the entire protocol. The largest average change in LPA over the course of a workday was measured during supine ultrasound with a mean descent of 6.1 degrees after the standing + low vocal load day and a mean descent of 6.0 degrees after the sitting + high vocal load day. The standing ultrasounds for sitting + high vocal load workday showed a slightly positive change in average LPA with the angle increasing 2.6 degrees at the end of this work condition. Standing ultrasounds had smaller changes in LPA over the workdays than the supine ultrasounds.

These preliminary findings show a greater reduction in support when measured in supine versus standing, however this is likely due to a lower LPA at the start of the day in standing compared to supine. These data show that both standing and high vocal load induce a similar change in LPA though, in contrast to the hypothesis, standing + high vocal load did not induce the greatest change. For the supine ultrasounds, however, the smallest change was seen after the sitting + low vocal load workday, which is consistent with the hypothesis.

This is the first study to explore how work position and occupational vocal load may be impacting pelvic floor support over the course of a workday. In this small cohort of asymptomatic women, both voicing and standing reduce pelvic floor support over the course of the workday when measured in supine. Standing and higher vocal load had greater impact on support that sitting and low vocal load, respectively. It is important that future studies investigate these factors in both women with pelvic floor disorders and voice or respiratory disorders as well. This knowledge can improve comprehensive conservative treatment by addressing work factors that have not previously been considered when rehabilitating pelvic floor conditions.

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