Pelvic floor muscle function in women with and without urinary incontinence: are strength and endurance the only relevant functions? a cross-sectional study.

Objectives: To investigate if pelvic floor muscle functions (PFMFs), besides strength and endurance, are associated with the occurrence of urinary incontinence (UI) in women, and to investigate which functions predict the occurrence of UI.

Design: Cross-sectional study.

Setting: Public health service and community.

Participants: Two hundred and ten women (101 with UI and 109 without UI).

Main Outcome Measures: PFMF was investigated by the Pelvic Floor Sensory and Muscle Function Exam (Exame das Funções Sensoriais e Musculares do Assoalho Pélvico), a valid and reliable instrument that measures the following functions: tone, reaction, control (contraction), control (relaxation), coordination, strength and endurance. The International Consultation on Incontinence Questionnaire-Short Form was used to document the occurrence and type of UI. Sociodemographic and clinical data were collected through the questionnaire. Chi-squared test, Student's t-test and Mann-Whitney test were used to evaluate the association of each function with UI. Two logistic regression models tested the predictive value of each function for UI: Model a included all of the above PFMFs and Model b included all of the above PFMFs except strength and endurance.

Results: Most sociodemographic and clinical risk factors differed between women with UI and women without UI. On univariate analysis, tone, reaction, control (contraction), coordination, strength and endurance were found to be significantly associated (P<0.05) with the occurrence of UI. On multivariate analysis, Model a explained 69% and Model b explained 61% of the likelihood of UI, respectively.

Conclusions: Besides strength and endurance, pelvic floor muscle tone, reaction, control (contraction) and coordination were significantly associated with the occurrence of UI, and should be investigated further.