Objective: The purpose of this study was to investigate the effect of variations in forced expiration effort on the automatic activation of pelvic floor (PF) muscles.
Study Design: Quasiexperimental repeated measures.
Background: The PF activates automatically, both squeezing and lifting, during times of increased intra-abdominal pressure for postural stability and continence. Expiration additionally produces automatic activation of the PF muscles. No study to date has investigated the effects of forced expiration on PF displacement and squeeze pressure.
Methods and Measures: A convenience sample of premenopausal, nulliparous, continent women was recruited and instructed on 3 variations in forced expiration effort: (1) minimum; (2) moderate; and (3) maximum. Pelvic floor automatic activation measurements were taken using perineometry (squeeze pressure) and transperineal ultrasound imaging (PF displacement) during each type of expiration. Chi-square test was used to analyze the direction of PF displacement, and Friedman analysis by ranks was used to analyze the magnitude of the squeeze pressure and PF displacement.
Results: Data of 18 women, aged 24.8 ± 2.5 years, were analyzed. There was a significant difference in the vaginal squeeze pressure (P < .001) and magnitude of displacement in the horizontal plane (P < .001) and the vertical plane (P < .001) of the PF between the 3 variations of expiration. Minimum effort of forced expiration created the most consistent PF displacement in a cranial-ventral direction.
Conclusions: Minimal forced expiration effort resulted in the most consistent PF cranial-ventral displacement with vaginal squeeze pressure. These findings provide basic science information on PF activation applicable to PF training programs.