ObjectiveOur study aimed to improve the understanding of the biomechanical changes occurring in the pelvic floor due to pelvic floor muscle training (PFMT), which is responsible for improving stress urinary incontinence (SUI) symptoms. Study designIn this prospective cohort study, we examined the impact of a six-week PFMT program in women with stress or stress-predominant urinary incontinence on the biomechanical parameters of the pelvic floor. Fifty-two biomechanical parameters were measured by Vaginal Tactile Imager (VTI) at baseline and at a six-week follow-up. In addition, we have assessed the Urinary Distress Inventory (UDI-6), Incontinence Impact Questionnaire (IIQ-7), and Patient’s Global Impression of Severity (PGI-S) scores at enrolment and at six-week follow-up. We have divided our cohort into two groups, Improved Group (IG) and Not-improved Group (NIG), based on the change in UDI-6 score after six weeks and compared the biomechanical changes within and between the two groups. ResultsThe overall cohort included twenty women with stress or stress-predominant SUI based on MESA questionnaire [MESA SUI index (mean ± SD) 63.3 % ± 24.0 %, MESA UUI index (mean ± SD) 13.3 % ± 15.3 %, p < 0.01]. Nine of the 52 VTI parameters have changed significantly after six weeks of PFMT in the entire cohort. Eleven women (IG) achieved the minimum 11-point change in the UDI-6 scaled score. In IG, we found that three VTI parameters differed significantly: Parameter 1: the maximum value of force measured during the VTI probe insertion [(N, mean ± SD) 0.55 ± 0.18 vs. 0.78 ± 0.31, p < 0.049], parameter 18: the maximum gradient at the upper third of the vagina (posterior) [(kPa/mm, mean ± SD) 0.16 ± 0.05 vs. 0.36 ± 0.28, p < 0.048], and parameter 47: integral force change in the anterior compartment at reflex pelvic muscle contraction (cough) [(N, mean ± SD) 1.61 ± 0.85 vs. 1.97 ± 0.71, p < 0.045]. ConclusionOur study revealed a significant association between the improvement of strength in targeted muscle groups and a reduction in urinary incontinence symptoms. Identifying specific muscles changing PFMT provides valuable insights for specific interventions. Our findings may help to create personalized and targeted interventions to improve the quality of life of women affected by SUI.