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.

The human pelvis is a complex structure, which participates in the biomechanical functioning of the musculoskeletal system. Although it is considered a symmetrical entity, the morphology of the pelvis is subject to different factors that alter its anatomy, function or biomechanics, such as age, bipedal locomotion, obstetric changes and sexual dimorphism. However, how these factors influence pelvic asymmetry is unknown. Some evidence suggests that this condition leads to different pathological states, such as chronic low back pain, scoliosis, post-traumatic pelvic dysfunctions and obstetric changes. Therefore, pelvic asymmetries present a significant challenge in clinical practice due to their multifactorial nature and their potential impact on quality of life. Multidisciplinary research and collaboration are essential to improve understanding and develop more effective and specific identification and treatment approaches in the presence of pelvic asymmetries.

This study aimed to identify if the muscle mechanical properties (MMPs) of both sides of pelvic floor muscles (PFMs) are symmetrical in different populations of both sexes. Between-sides comparisons of MMPs of PFMs, assessed with manual myotonometry, were performed in three groups, with 31 subjects each, composed of healthy nulliparous women (without any type of delivery or pregnancy), multiparous women (with at least two vaginal deliveries), and healthy adult men. Intra-group correlations between MMPs and age, body mass index (BMI), or clinical state of pelvic floor were also obtained. The nulliparous women and the men showed no between-sides differences in any MMP of PFMs. However, the multiparous women showed that the right side displayed less frequency (−0.65 Hz, 95% CI = −1.01, −0.20) and decrement (0.5, 95% CI = 0.11, 0.01), and more relaxation (1.00 ms, 95% CI = 0.47, 1.54) and creep (0.07 De, 95% CI = 0.03, 0.11), than the left side. Further, MMPs were related to age, sex, and BMI, also depending on the population, with the multiparous women being the only group with some between-sides asymmetries, which in this case were positive and of fair intensity for the left side of the PFMs, between BMI, and frequency and stiffness (rho Spearman coefficient: 0.365 and 0.366, respectively). The symmetry of MMPs of the PFMs could depend on the subject’s condition. Multiparous women show a higher tendency to asymmetries than nulliparous women and men, which should be considered in research and clinical settings.

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.

Background/Objectives: To compare the lumbopelvic muscle mechanical properties (MMPs) of women with and without multiple sclerosis (MS) and explore relationships between these properties and sociodemographic/clinical characteristics. Methods: This cross-sectional observational study included 22 women with MS and 22 age- and BMI-matched women without MS. MMPs (frequency, stiffness, decrement, relaxation, and creep) of pelvic floor and lumbar paravertebral muscles were assessed using a MyotonPRO device. Sociodemographic and clinical data related to pelvic floor health were also collected. Results: Women with MS showed significant differences in pelvic floor MMPs, including higher frequency (3.26 Hz; 95% CI [2.12, 4.41]), stiffness (90 N/m; 95% CI [55.09, 124.91]), and decrement (0.2; 95% CI [0.09, 0.31]) and lower relaxation (6.15 ms; 95% CI [8.26, 4.05]) and creep (0.24; 95% CI [0.34, 0.13]) compared to women without MS. For lumbar paravertebral muscles, differences were observed only on the right side, with lower frequency (2.15 Hz; 95% CI [0.28, 4.02]) and stiffness (62.17 N/m; 95% CI [10.7, 113.65]) in women with MS. Correlation patterns between MMPs and clinical characteristics differed by group, with moderate correlations found only in the MS group (e.g., EDSS: r = 0.57; p = 0.006; PFDI-20: r = 0.47; p = 0.026). Conclusions: Women with MS exhibit altered pelvic floor MMPs, characterized by reduced tone and stiffness and increased elasticity and viscoelasticity, while lumbar paravertebral differences are minimal. These findings highlight the need for objective MMP assessments in women with MS to guide preventive and therapeutic interventions.