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

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.

Absolute and Relative Reliability of the Assessment of the Muscle Mechanical Properties of Pelvic Floor Muscles in Women with and without Urinary Incontinence.

An analysis of the muscle mechanical properties (MMPs) of the pelvic floor muscles (PFMs) is relevant for understanding the physiopathology of urinary incontinence (UI). However, there is no objective and reliable methodology currently available for quantifying the MMPs of PFMs. Thus, the objective was to determine the intra-rater and inter-rater reliability of the MMPs of PFM assessment with a hand-held tonometer device, called the MyotonPRO, in young women with and without UI. Sociodemographic and pelvic floor questionnaires, plus MMPs of PFMs were assessed in 38 nulliparous women with UI and 40 matched healthy women by two trained physiotherapists on two different occasions, 48-72 h apart. Good to excellent absolute reliability was found for tone, stiffness, and decrement of both intra- and inter-rater analyses in both study groups (Intraclass Correlation Coefficient ranged from 0.75 to 0.92), with a trend of lower values for relaxation and creep. The standard error of measurement (SEM) did not achieve 10% of the mean values for any MMPs. The minimum detectable change (MDC) values were also provided for clinical applications. In conclusion, the relative reliability of tone, stiffness, and the assessment of the decrement of PFMs with MyotonPRO is good to excellent for UI and healthy women. The SEM and MDC values were acceptable for their application in clinical settings.