Influence of vaginal birth on lumbopelvic muscle mechanical properties on urinary incontinence.

ABSTRACT

OBJECTIVE: To identify differences in the muscle mechanical properties of the pelvic floor (PF) and lumbar paravertebral (LP) muscles between young nulliparous and uni/multiparous women. Secondarily, specific behaviors, depending on the presence or absence or urinary incontinence (UI), were also researched. DESIGN: Case-control study. SETTING: Higher education institution. PARTICIPANTS: One hundred young women participated, divided into two groups depending on whether they had vaginal birth (nulliparous or uni/multiparous). Each group included women with and without UI. MAIN MEASURES: A muscle mechanical properties (tone, stiffness, decrement-inverse of elasticity-, and viscoelastic properties relaxation and creep) assessment of the PF and LP muscles were performed with a hand-held tonometer. RESULTS: Tone and stiffness of both sides of the PF presented group by UI interaction (p < 0.05), with uni/multiparous women with UI showing higher tone and stiffness compared to multiparous women without UI. In LP muscles, uni/multiparous women showed greater tone and stiffness on the right and left sides [-2.57 Hz (95% confidence interval -4.42,-0.72) and -79.74 N/m (-143.52,-15.97); -2.20 Hz (-3.82,-0.58) and -81.30 N/m (-140.66-,21.95), respectively], as well as a decrease in viscoelastic properties compared to nulliparous women [relaxation 2.88 ms (0.31,5.44); creep 0.15 (0.01,0.30); relaxation 2.69 ms (0.13,5.25); creep 0.14 (0,0.28), respectively]. CONCLUSIONS: Vaginal birth and UI have a differential influence on the muscle mechanical properties of the PF and LP muscles. The determination of muscle mechanical properties by externally applied hand-held tonometry improves the knowledge of the lumbopelvic status, with applicability in clinical and research fields.