Urinary incontinence (UI) is a prevalent condition in women that negatively affects quality of life, psychosocial well-being, daily participation, and work productivity. Conservative management is recommended as first-line treatment and typically includes pharmacological therapy, bladder training, and pelvic floor muscle training over a period of at least six months [1].
The pathophysiology of UI is commonly attributed to pelvic floor muscle (PFM) weakness [2,3]. However, this assumption may not apply uniformly across different UI subtypes. Understanding potential differences in PFM function between UI types is important for informing rehabilitation strategies.
The aim of this study was to compare PFM activity among women with stress, urgency, and mixed urinary incontinence using surface electromyography, and to determine whether PFM activity patterns differ across UI subtypes.

This observational cross-sectional study compared pelvic floor muscle activity across urinary incontinence subtypes in women.
Women aged 25–75 years with symptoms of stress urinary incontinence (SUI), urgency urinary incontinence (UUI), or mixed urinary incontinence (MUI) were included. UI subtype classification was based on symptom predominance. Exclusion criteria included prior pelvic or urological surgery, neurological disorders affecting pelvic floor function, postpartum period within two years, and inability to comply with the study protocol. The study was conducted in accordance with the Declaration of Helsinki, and all participants provided written informed consent.
Pelvic floor muscle (PFM) activity was evaluated using surface electromyography (sEMG). Measurements were performed in the supine position with electrode placed in the perianal region and a reference electrode on the inner thigh. Participants were instructed to perform isolated PFM contractions without activation of accessory muscles. For the contraction phase, mean activity (μV), peak activity (μV), maximum voluntary contraction (MVC%), and onset of muscle activation (reaction time, s) were recorded. For the resting phase, mean activity (μV), minimum activity (μV), MVC%, and time to return to baseline muscle activity (s) were analyzed.
Sample size estimation based on pilot data indicated a target sample of 87 participants. The present analysis includes data from participants recruited to date as part of this ongoing study.
Data are presented as median and interquartile range. Normality assumptions were not met; therefore, non-parametric tests were applied. Comparisons between groups were performed using the Kruskal–Wallis test. Pairwise comparisons were conducted using the Mann–Whitney U test with Bonferroni correction (p<0.016). A p-value <0.05 was considered statistically significant.

Twenty-six women were included (SUI: n=7, UUI: n=7, MUI: n=12). The median age was 47 years. No significant between-group differences were observed in demographic and clinical characteristics (p>0.05).
Significant differences were found between incontinence subtypes in onset of muscle activation (p=0.044), resting average activity (p=0.047), and resting MVC (p=0.043), while other sEMG parameters were comparable across groups (p>0.05). However, pairwise comparisons did not remain significant after Bonferroni correction.

These findings suggest that pelvic floor muscle activity may differ across urinary incontinence subtypes, particularly in terms of resting muscle behavior and activation timing. Although pairwise comparisons were not statistically significant after correction, consistent patterns were observed, with a tendency toward higher resting activity and faster activation in urgency-related subtypes. The observed differences were more pronounced in resting muscle activity than in contraction-related parameters. This may indicate that pelvic floor dysfunction in certain subtypes is not solely characterized by muscle weakness, but may also involve altered muscle activity and impaired relaxation.

Pelvic floor muscle activity patterns may differ across urinary incontinence subtypes, highlighting the importance of considering muscle behavior, beyond strength, in clinical decision-making and individualized rehabilitation.

C.K. Harding, M.C.L., S. Arlandis, K. Bø, H. Cobussen-Boekhorst, E. Costantini, J. Groen, A.K. Nambiar, M.I. Omar, B. Peyronnet, V. Phé, C.H. van der Vaart., Management of Non-Neurogenic Female Lower Urinary Tract Symptoms, in EAU Guidelines. 2023, EAU Guidelines Office, Arhem, The Netherlands.
Sapsford, R. R., Richardson, C. A., Maher, C. F., & Hodges, P. W. (2008). Pelvic floor muscle activity in different sitting postures in continent and incontinent women. Archives of physical medicine and rehabilitation, 89(9), 1741–1747. https://doi.org/10.1016/j.apmr.2008.01.029
Di Benedetto, P., Coidessa, A., & Floris, S. (2008). Rationale of pelvic floor muscles training in women with urinary incontinence. Minerva ginecologica, 60(6), 529–541.