Crosstalk considerations in studies evaluating pelvic floor muscles using surface electromyography in women: a scoping review

Techniques for Registration of Myoelectric Activity of Women's Pelvic Floor Muscles: A Scoping Review

INTRODUCTION AND HYPOTHESIS

Surface electromyography is commonly applied to measure the electrophysiological activity of the neuromuscular system. However, there is no consensus regarding the best protocol to assess pelvic floor muscles.

METHODS

A scoping literature review was carried out in six databases, using MeSH descriptors. It included studies with electromyographic assessment in adult women presenting or not with pelvic floor dysfunction. The results were presented in categories to contribute to the development of a protocol considering the most used parameters for non-invasive assessment of myoelectric activity of pelvic floor muscles.

RESULTS

A total of 1,074 articles were identified, and 146 studies were selected for analysis. The intravaginal probe was used in 80.8% of the studies, the bipolar sensor with metallic plates placed on both sides of the vagina was the most frequent (71.3%), with a reference electrode positioned on the anterior superior iliac spine (33.5%). The supine position with hip and knee flexed (45.2%) was the most frequent position used. Of the studies, 44.5% normalized the data by maximum voluntary contraction (MVC) whereas 44.5% performed an average of 3 MVCs.

CONCLUSIONS

The most frequently used protocol for the pelvic floor is the bipolar intracavitary probe with metal plates positioned at 3-9 o'clock and introduced distally to the vaginal introitus with the volunteer in the supine position and the hip and knee flexed with the reference placed on the anterior-superior iliac spine.

Functional Exercise Versus Specific Pelvic Floor Exercise: Observational Pilot Study in Female University Students

OBJECTIVES

To evaluate the electromyographic (EMG) activity of the pelvic floor musculature (PFM) that takes place when performing the functional movement screen (FMS) exercise, comparing it with the activation in the maximum voluntary contraction of PFM in the supine position (MVC-SP) and standing (MVC-ST).

MATERIAL AND METHODS

A descriptive, observational study conducted in two phases. In the first study phase, the baseline EMG activity of PFM was measured in the supine position and standing during MVC-SP and MVC-ST and during the execution of the seven exercises that make up the FMS. In the second phase of the study, the baseline EMG activity of PFM was measured in the supine position and standing during MVC-SP and MVC-ST and during the FMS exercise that produced the most EMG in the pilot phase: trunk stability push-up (PU). ANOVA, Friedman's and Pearson's tests were used.

RESULTS

All FMS exercises performed in the pilot phase showed a value below 100% maximum voluntary contraction (MVC) except PU, which presented an average value of 101.3 μv (SD = 54.5): 112% MVC (SD = 37.6). In the second phase of the study, it was observed that there were no significant differences (p = 0.087) between the three exercises performed: MVC-SP, MVC-ST and PU (39.2 μv (SD = 10.4), 37.5 μv (SD = 10.4) and 40.7 μv (SD = 10.2), respectively).

CONCLUSIONS

There is no evidence of the existence of significant differences in EMG activation in PFM among the three exercises analysed: MVC-SP, MVC-ST and PU. The results show better EMG values in the functional exercise of PU.

Characterizing Pelvic Floor Muscle Activity During Walking and Jogging in Continent Adults: A Cross-Sectional Study

Introduction

The pelvic floor muscles (PFM) are active during motor tasks that increase intra-abdominal pressure, but little is known about how the PFM respond to dynamic activities, such as gait. The purpose of this study was to characterize and compare PFM activity during walking and jogging in continent adults across the entire gait cycle.

Methods

17 able-bodied individuals (8 females) with no history of incontinence participated in this study. We recorded electromyography (EMG) from the abdominal muscles, gluteus maximus (GM), and PFM while participants performed attempted maximum voluntary contractions (aMVC) of all muscles and completed 60–70 strides in four gait conditions: slow walk (1 km/h); regular walk (self-selected comfortable pace); transition walk (self-selected fastest walking pace); jog (same speed as transition walking). We quantified activity throughout the whole gait cycle (%aMVCGC) and during periods of bursting (%aMVCBR) for each participant, and analyzed the timing of PFM bursting periods to explore when the PFM were most active in the gait cycle. We also conducted a phase metric analysis on the PFM and GM burst timings. We performed a Spearman's rank-order correlation to examine the effect of speed on %aMVCGC, %aMVCBR, and phase metric score, and used the Wilcoxon Signed-Rank test to evaluate the effect of gait modality, matched for speed (walking vs. jogging), on these variables.

Results

The PFM were active throughout the gait cycle, with bursts typically occurring during single-leg support. The PFM and GM were in phase for 44–69% of the gait cycle, depending on condition. There was a positive correlation between gait speed and both %aMVCGC and %aMVCBR (p < 0.001). Phase metric scores were significantly higher during jogging than transition walking (p = 0.005), but there was no difference between gait modality on %aMVCGC or %aMVCBR (p = 0.059). Where possible we disaggregated data by sex, although were unable to make statistical comparisons due to low sample sizes.

Conclusion

The PFM are active during walking and jogging, with greater activity at faster speeds and with bursts in activity around single-leg support. The PFM and GM co-activate during gait, but are not completely in phase with each other.

Are clinically recommended pelvic floor muscle relaxation positions really efficient for muscle relaxation?

INTRODUCTION AND HYPOTHESIS

Various positions for pelvic floor muscle (PFM) relaxation are recommended during PFM training in physiotherapy clinics. To our knowledge, there is no study addressing the most effective position for PFM and abdominal muscle relaxation. Therefore, the current study aimed to investigate the effect of different relaxation positions on PFM and abdominal muscle functions in women with urinary incontinence (UI).

METHODS

Sixty-seven women diagnosed with UI were enrolled in the study. The type, frequency, and amount of UI were assessed with the International Incontinence Questionnaire-Short Form and bladder diary. Superficial electromyography was used to assess PFM and abdominal muscle functions during three relaxation positions: modified butterfly pose (P1), modified child pose (P2), and modified deep squat with block (P3). Friedman variance analyses and Wilcoxon signed rank test with Bonferroni corrections were used to evaluate the difference between positions.

RESULTS

The most efficient position for PFM relaxation was P1 and followed by P3 and P2, respectively. The order was also the same for abdominal muscles (p < 0.001), P1 > P3 > P2. The rectus abdominis (RA) was the most affected muscle during PFM relaxation. The extent of relaxation of RA muscle increased as the extent of PFM relaxation increased (r = 0.298, p = 0.016). No difference was found between different types of UI during the same position in terms of PFM relaxation extents (p > 0.05).

CONCLUSIONS

Efficient PFM relaxation is maintained during positions recommended in physiotherapy clinics. The extent of PFM and abdominal muscle relaxation varies according to the positions.

Reliability, validity and responsiveness of pelvic floor muscle surface electromyography and manometry

INTRODUCTION AND HYPOTHESIS

Vaginal surface electromyography (sEMG) is commonly used to assess pelvic floor muscle (PFM) function and dysfunction but there is a lack of studies regarding the assessment properties. The aim of the study was to test the hypotheses that sEMG has good test-retest intratester reliability, good criterion validity and is responsive to changes compared to manometry.

METHODS

PFM resting tone, maximum voluntary contraction (MVC) and endurance were measured in 66 women with pelvic floor dysfunction. One assessment by manometry was followed by two testing sessions with sEMG at baseline. After 4 to 42 weeks of supervised PFM strength training, 29 participants were retested with both devices.

RESULTS

Median age of the participants was 41 years (range 24-83) and parity 2 (range 0-10). Very good test-retest intratester reliability was found for all three sEMG measurements. The correlation between sEMG and manometry was moderate for vaginal resting tone (r = 0.42, n = 66, p < 0.001) and strong for MVC (r = 0.66, n = 66, p < 0.001) and endurance (r = 0.67, n = 66, p < 0.001). Following the strength training period, participants demonstrated increased MVC and endurance measured with manometry, but not with sEMG. A significant reduction in resting tone was found only with sEMG.

CONCLUSION

sEMG is reliable and correlates well with manometry. However, sEMG is not as responsive as manometry for changes in PFM MVC and endurance. For measurement of PFM resting tone, sEMG seems more responsive than manometry, but this requires further investigation.

Surface electromyography of the pelvic floor at 6-8 weeks following delivery: a comparison of different modes of delivery

INTRODUCTION AND HYPOTHESIS

The objective of this study was to compare the impact of different modes of delivery, especially forceps delivery (FD), on pelvic floor muscles (PFMs) through vaginal surface electromyography (sEMG) in primiparous women at early (6-8 weeks) postpartum.

METHODS

A total of 1259 primiparous women with full-term singleton births were included in this cross-sectional study. Of these, 98 were delivered by forceps, 865 underwent spontaneous vaginal delivery (SD) and 296 underwent elective cesarean delivery (CD). Clinical demographic characteristics and vaginal sEMG variables of parturients 6-8 weeks after birth were collected and analyzed using SPSS software. One-way ANOVA with Bonferroni correction, Chi-square test or Student's t-test was used according to the variable type. Spearman correlation and binary logistic regression analyses were also used. P/α ≤ 0.05 was considered statistically significant.

RESULTS

Amplitude of fast and sustained contractions on sEMG in the FD group was significantly lower compared with the CD and SD groups. The sEMG amplitude of all contractions was significantly higher in the CD group compared with the FD and SD groups (P < 0.01). According to binary logistic regression analysis, mode of delivery was a major influencing factor in sEMG.

CONCLUSIONS

An early postpartum sEMG test appears to be helpful for the assessment of PFM activity. Mode of delivery was a major influencing factor on sEMG. Forceps delivery significantly inversely influenced PFM activity.

Using Preoperative Pelvic Floor Assessment to Predict Early Return of Continence after Robotic Radical Prostatectomy

OBJECTIVE

To evaluate whether pre-operative pelvic floor physical therapy (PFPT) parameters may predict early return of urinary continence after RP. While long-term urinary continence is eventually achieved in most patients who undergo radical prostatectomy (RP), predicting when patients will become continent is challenging. Prior studies aiming to predict return of post-operative continence have not evaluated patient-specific pelvic floor strength parameters.

METHODS

We reviewed a prospectively maintained database of patients undergoing RP who underwent pre-operative PFPT consultation and completed 3-month patient-reported quality of life evaluation. Trained therapists documented pelvic strength parameters. Urinary continence was defined as using 0 or 1 pad per day. We evaluated the association of PFPT parameters with urinary continence at 3 months, adjusting for other factors that could affect continence.

RESULTS

144 men met inclusion criteria. The majority of patients underwent nerve-sparing procedures and had intermediate- or high-risk prostate cancer. At 3 months, 90 of 144 (62.5%) were continent, while 54 of 144 (37.5%) were not. On multivariable analysis, prostate volume (OR 0.98, 95% CI 0.96-1.00) and pelvic floor endurance (OR 2.71, 95% CI 1.23-6.17) were significantly associated with being continent at 3 months. 56 of 76 (74%) men with good pelvic floor endurance were continent at 3 months, while only 34 of 68 (50%) men with poor endurance were continent (P = .006).

CONCLUSION

Pre-operative assessment of pelvic floor endurance is an objective measure that may allow more accurate prediction of early continence after radical prostatectomy. Improved patient counseling could positively impact patient satisfaction and quality of life and reduce decision regret.

Techniques for registration of myoelectric activity of women's pelvic floor muscles: a scoping review protocol

OBJECTIVE

The objective of this review is to identify the most frequently used protocols for analyzing the myoelectric activity of the pelvic floor muscles during surface electromyography in women aged 18 years or older.

INTRODUCTION

Surface electromyography is normally used in assessment and treatment for research purposes when it is intended to quantitatively measure the electrophysiological behavior of the neuromuscular system. However, although there are internationally standardized, non-invasive assessment protocols for most muscle groups, there is no consensus for pelvic floor muscles, which makes it difficult to standardize in scientific research and clinical applicability.

INCLUSION CRITERIA

Studies that explore registration protocols and filtering parameters of surface electromyographic signals in women aged over 18 years old with or without pelvic floor dysfunction will be considered. Studies encompassing either electromyographic biofeedback as a treatment resource only or electroneuromyography (needle electrode) will be excluded.

METHODS

Primary studies published in the previous 10 years in MEDLINE, Embase, Scopus, Web of Science, CINAHL, and Cochrane Central databases will be included. The search will encompass descriptors registered in MeSH. The identified articles will be assessed for eligibility by two independent reviewers in three stages: evaluation by title, abstract, and full text. If there is any disagreement, a third reviewer will be consulted. Data will be extracted and organized in standardized spreadsheets. The results will be assigned to categories in order to facilitate the organization of a protocol with the most commonly used parameters for non-invasive assessment of myoelectric activity of pelvic floor muscles.

Surface EMG in Clinical Assessment and Neurorehabilitation: Barriers Limiting Its Use

This article addresses the potential clinical value of techniques based on surface electromyography (sEMG) in rehabilitation medicine with specific focus on neurorehabilitation. Applications in exercise and sport pathophysiology, in movement analysis, in ergonomics and occupational medicine, and in a number of related fields are also considered. The contrast between the extensive scientific literature in these fields and the limited clinical applications is discussed. The "barriers" between research findings and their application are very broad, and are longstanding, cultural, educational, and technical. Cultural barriers relate to the general acceptance and use of the concept of objective measurement in a clinical setting and its role in promoting Evidence Based Medicine. Wide differences between countries exist in appropriate training in the use of such quantitative measurements in general, and in electrical measurements in particular. These differences are manifest in training programs, in degrees granted, and in academic/research career opportunities. Educational barriers are related to the background in mathematics and physics for rehabilitation clinicians, leading to insufficient basic concepts of signal interpretation, as well as to the lack of a common language with rehabilitation engineers. Technical barriers are being overcome progressively, but progress is still impacted by the lack of user-friendly equipment, insufficient market demand, gadget-like devices, relatively high equipment price and a pervasive lack of interest by manufacturers. Despite the recommendations provided by the 20-year old EU project on "Surface EMG for Non-Invasive Assessment of Muscles (SENIAM)," real international standards are still missing and there is minimal international pressure for developing and applying such standards. The need for change in training and teaching is increasingly felt in the academic world, but is much less perceived in the health delivery system and clinical environments. The rapid technological progress in the fields of sensor and measurement technology (including sEMG), assistive devices, and robotic rehabilitation, has not been driven by clinical demands. Our assertion is that the most important and urgent interventions concern enhanced education, more effective technology transfer, and increased academic opportunities for physiotherapists, occupational therapists, and kinesiologists.

Activation patterns of pelvic floor muscles in women with incontinence while running: a randomized controlled trial

INTRODUCTION AND HYPOTHESIS

Running is known to cause urinary leakage in women with stress urinary incontinence (SUI). Task-specific fiber-type recruitment while running can be estimated using wavelets. The aim of this study was to compare the effect of a new physiotherapy program including involuntary, reflexive training with a standard physiotherapy program on pelvic floor muscle (PFM) activation patterns and fiber-type recruitment behavior while running.

METHODS

In this triple-blinded randomized controlled trial, women with SUI were randomly allocated to the control group (CON), which performed a standard physiotherapy program, or the experimental group (EXP), which received additional involuntary, reflexive training. PFM electromyography (EMG) was recorded during 10 s at three running speeds and analyzed using Morse wavelets. The relative distribution of power (%) over the frequencies from 20 to 200 Hz was extracted and analyzed within six-time intervals of 30 ms. Statistical nonparametric mapping was performed to identify power spectra differences.

RESULTS

Thirty-nine (CON) and 38 (EXP) women were included. The power spectra showed no statistically significant group differences. The time intervals from 30 ms before to 30 ms after initial contact showed significantly lower intensities than the intervals from 30 to 150 ms after initial contact in the lowest and higher intensities in the highest frequencies for all running speeds and both groups.

CONCLUSIONS

Power spectra shifts toward higher frequency bands in the pre-initial contact phase could indicate a feed-forward anticipation and a muscle tuning for the expected impact of initial contact event in order to maintain continence.

Development of a wireless accelerometer-based Intravaginal device to detect pelvic floor motion for evaluation of pelvic floor dysfunction

Urinary incontinence (UI) is experienced by an estimated 51% of women in the U.S. and often results from impaired function or weakening of the pelvic floor muscles. Pelvic floor muscle training (PFMT) is a frontline nonsurgical treatment, yet a number of symptomatic individuals cannot accurately perform a pelvic floor muscle contraction with simple verbal or written instruction. Long-term adherence to PFMT regimens is often a barrier to resolution of symptoms. Various biofeedback tools have been utilized to aid correct pelvic floor muscle performance and adherence. One novel device, the leva® Pelvic Digital Health System, utilizes an intravaginal probe embedded with MEMS accelerometer sensors that allow real-time visualization of the shape and motion of the vagina during PFMT. Early positive results with this device prompted design of a wearable version. The purpose of this study was to design a wearable, wireless clinical research device to optimize MEMS accelerometer sensor placement to detect maximal movement during a pelvic floor muscle exercise (PFME) and to test the form factor for retention and user acceptability. The device comprised a ring designed to sit at the fornix with an extension following the length of the vagina. This paper presents design components and results from clinical testing of 10 subjects. It was determined that a ring form factor alone, similar to other vaginal rings (pessaries, estrogen rings) provided less accurate visual information about PFME performance. By contrast, we determined that a ring with an extension allowed for device retention and improved real-time detection of vaginal shape and motion during PFMT.

Electromyography of pelvic floor muscles with true differential versus faux differential electrode configuration

INTRODUCTION AND HYPOTHESIS

In pelvic floor muscle (PFM) electromyography (EMG) two different bipolar configurations are applied: "true differential" configuration (TD) measures neuromuscular activity with two ipsilateral electrodes, whereas "faux differential" configuration (FD) has two electrodes placed on each side of the PFMs. The aim of the study was to determine possible differences and the relationship between both configurations.

METHODS

A secondary data analysis of 28 continent (CON) and 22 stress urinary incontinent (SUI) women was performed. Surface EMG was measured using a vaginal probe during maximal voluntary (MVC) and fast voluntary (FVC) contractions. TD and FD were explored with amplitude- and time-related EMG parameters, cross-correlation coefficients (R(0)) and statistical parametric mapping (SPM).

RESULTS

Of a total of 62 comparisons of EMG parameters of MVC and FVC, only one comparison showed significant differences between the two configurations (CON group, FVC_4peak TD versus FD, p = 0.015). R(0) were high in both groups for all MVC and FVC variables (R(0) ≥ 0.989). SPM detected 3 out of 28 comparisons with short (0.124-0.404 s) significant supra-threshold clusters (p < 0.025).

CONCLUSIONS

The findings suggest that TD and FD might measure neuromuscular activity almost the same. Very high cross-correlation coefficients and a very limited number of significant results from EMG parameters, as well as SPM, suggest that in the measured sample the choice of TD or FD might remain practically irrelevant. To gain further insight into the scientific and clinical relevance of choosing either of the electrode configurations, the comparisons should be re-evaluated on a sample with more severe incontinence symptoms.

Are there differences in short-term pelvic floor muscle function after cesarean section or vaginal delivery in primiparous women? A systematic review with meta-analysis

INTRODUCTION AND HYPOTHESIS

The literature presents controversial results regarding the role of delivery mode in pelvic floor muscle (PFM) function after birth. Some studies showed a greater impairment of PFM function after vaginal delivery compared with cesarean section, while others have not identified a significant difference between these two modes of delivery. This study aimed to investigate whether there was a difference in short-term PFM function after childbirth in primiparous women who underwent cesarean section compared with those who underwent vaginal delivery.

METHODS

Up to December 2018, the PubMed-MEDLINE, CINAHL, Embase, Bireme, Scopus, Web of Science, and Science Direct databases were searched. Two independent reviewers performed the selection process based on titles, abstracts, and full-text reading. Observational studies comparing PFM function after cesarean section versus vaginal delivery in primiparous women were included. PRISMA guidelines and Cochrane recommendations were followed. Methodological quality of the primary studies was assessed through the checklist proposed by the Joanna Briggs Institute for cross-sectional studies. Random effects meta-analysis was performed to synthesize evidence regarding PFM strength in primiparous woman after vaginal delivery compared with cesarean section. The GRADE approach was applied to classify the quality of the evidence.

RESULTS

Eleven studies met the inclusion criteria and were included in this review. A total of 1726 primiparous women were analyzed after childbirth. Five studies were included in the meta-analysis. No difference in PFM strength after childbirth was identified when cesarean section was compared with vaginal delivery [standardized mean difference (SMD): -0.15, 95% confidence interval (CI): -0.85 to 0.56]. Differences in PFM strength were identified when patients who underwent cesarean section were compared with those with an episiotomy or instrumented vaginal delivery (SMD: -12.51, CI 95%: -24.57 to -0.44), favoring the cesarean section group. In both cases, the quality of evidence was classified as very low because of the observational design of the included studies and population heterogeneity.

CONCLUSION

There was no difference in short-term PFM strength after childbirth between primiparous women who underwent cesarean section or vaginal delivery, as assessed through vaginal manometry. However, we identified reduced PFM strength in women who underwent an episiotomy or instrumented vaginal delivery compared with those who underwent cesarean section. Nevertheless, this conclusion should be cautiously considered as the observational design of the primary studies and possible heterogeneity among the primiparous women included in the studies contributed to reducing the quality of the evidence synthesized. Future primary studies with longitudinal designs and long-term follow-up periods are needed to strengthen the quality of evidence and provide more conclusive evidence to guide clinical practice.

Pelvic floor and abdominal muscle responses during hypopressive exercises in women with pelvic floor dysfunction

AIM

To measure the neuromuscular activation of the pelvic floor and abdominal muscles concurrently with vaginal closure forces induced during a hypopressive exercise (HE) and to identify the contribution of the HEs sequences (posture and maneuver) in the muscle's activation.

METHODS

A cross-sectional study design was employed. Sixty-six women who had participated in a physical therapy program focused on HEs were recruited. Pelvic floor muscle (PFM) activation was measured using surface electromyography (sEMG) in supine and in the orthostatic position, and vaginal closure force was measured through vaginal dynamometry in supine. Activation of the abdominal, gluteal, and hip adductor muscles was measured using sEMG. Maximum effort voluntary contractions (MVCs) of the PFMs and reference contractions of the abdominal and hip muscles were acquired for normalization purposes. A HE was then performed in a supine position with one leg raised, then in an orthostatic position.

RESULTS

During the supine HE, the peak PFM sEMG amplitude was 74.4% to 86.5% (49.6%-109.6%) of MVC, the peak vaginal closure force was between 51.2% and 55.7% (95.5%-382.9%) of MVC, and the muscles of the lateral abdominal wall were activated between 25.4% and 35.3% of the reference contraction. During the orthostatic HE, PFM activation was 61.4% (40.1%-105.6%) of MVC, and the lateral abdominal wall muscles contracted at 22.8% of the reference activation level.

CONCLUSIONS

The PFMs, abdominal, gluteal, and adductor muscles are activated during the performance of a HE. The activation level of the PFMs and abdominal muscles is likely insufficient to result in strength gains; however, they could have an endurance effect.

The urethral hanging theory and how it relates to Enhörning's theory and the integral theory

Introduction and hypothesis

The article discusses three theories of stress urinary incontinence, the urethral hanging theory, Enhörning’s theory, and the integral theory.

Methods

The abdominal pressure transmission theory proposed by Enhörning is often misunderstood. It is regularly interpreted to mean that, in cases of stress urinary incontinence, the bladder neck descends outside the abdominal cavity, and treatment must involve elevating or repositioning the bladder neck.

Results

However, this actually contradicts the information provided in Enhörning’s original paper. The urethral hanging theory accepts the core of Enhörning’s theory and the integral theory rejects it. The three theories have different views on closure and opening of the bladder neck and on the pathophysiology of urethral funneling.

Conclusion

These differences are described and discussed.

Evaluation of an accelerometer-based digital health system for the treatment of female urinary incontinence: A pilot study

Aims

To assess the effectiveness and patient satisfaction of pelvic floor muscle training (PFMT) guided by an intravaginal accelerometer‐based system for the treatment of female urinary incontinence (UI).

Methods

Premenopausal women with mild‐to‐moderate stress or mixed UI were recruited to participate in PFMT with an accelerometer‐based system for 6 weeks with supervision. Objective outcomes included pelvic floor muscle (PFM) contraction duration, number of contractions in 15 seconds, and angular displacement of the accelerometer relative to earth during PFM contraction. Subjective outcomes and quality‐of‐life were assessed with validated, condition‐specific questionnaires. Results are presented as means, standard error of the mean, and 95% confidence intervals unless otherwise indicated.

Results

Twenty‐three women (age 42.0 ± 10.7 years, mean ± standard deviation) completed the study. Scores on the Urogenital Distress Inventory (UDI) decreased from 36.7 ± 4.7 at baseline to 1.45 ± 0.8 at 6 weeks (P < .0001). The Patient's Global Impression of Severity score decreased from 1.5 ± 0.1 to 0.2 ± 0.1 (P < .0001) at study endpoint. At 6 weeks, the PFM contraction duration increased from 13 ± 2.6 at baseline to 187 ± 9.6 seconds (P < .0001). Repeated contractions in 15 seconds increased from 5.9 ± 0.4 at enrollment to 9.6 ± 0.5 at 6 weeks (P < .0001). Maximum pelvic floor angle (a measure of lift) increased from 65.1 ± 2.0° to 81.1 ± 1.8° (P < .0001). Increasing PFM contraction duration and maximum pelvic floor angle correlated with decreasing UDI‐6 scores, r = −0.87, P = .01; r = −0.97, P = .0003, respectively. No device‐related adverse events occurred.

Conclusions

Pilot testing of this accelerometer‐based system demonstrates improvements in objective PFM measures, patient‐reported UI severity and condition‐specific quality of life, with results evident after 1 week of use.

A review on crosstalk in myographic signals

PURPOSE

Crosstalk in myographic signals is a major hindrance to the understanding of local information related to individual muscle function. This review aims to analyse the problem of crosstalk in electromyography and mechanomyography.

METHODS

An initial search of the SCOPUS database using an appropriate set of keywords yielded 290 studies, and 59 potential studies were selected after all the records were screened using the eligibility criteria. This review on crosstalk revealed that signal contamination due to crosstalk remains a major challenge in the application of surface myography techniques. Various methods have been employed in previous studies to identify, quantify and reduce crosstalk in surface myographic signals.

RESULTS

Although correlation-based methods for crosstalk quantification are easy to use, there is a possibility that co-contraction could be interpreted as crosstalk. High-definition EMG has emerged as a new technique that has been successfully applied to reduce crosstalk.

CONCLUSIONS

The phenomenon of crosstalk needs to be investigated carefully because it depends on many factors related to muscle task and physiology. This review article not only provides a good summary of the literature on crosstalk in myographic signals but also discusses new directions related to techniques for crosstalk identification, quantification and reduction. The review also provides insights into muscle-related issues that impact crosstalk in myographic signals.

Modern Theories of Pelvic Floor Support : A Topical Review of Modern Studies on Structural and Functional Pelvic Floor Support from Medical Imaging, Computational Modeling, and Electromyographic Perspectives

PURPOSE OF REVIEW

Weakened pelvic floor support is believed to be the main cause of various pelvic floor disorders. Modern theories of pelvic floor support stress on the structural and functional integrity of multiple structures and their interplay to maintain normal pelvic floor functions. Connective tissues provide passive pelvic floor support while pelvic floor muscles provide active support through voluntary contraction. Advanced modern medical technologies allow us to comprehensively and thoroughly evaluate the interaction of supporting structures and assess both active and passive support functions. The pathophysiology of various pelvic floor disorders associated with pelvic floor weakness is now under scrutiny from the combination of (1) morphological, (2) dynamic (through computational modeling), and (3) neurophysiological perspectives. This topical review aims to update newly emerged studies assessing pelvic floor support function among these three categories.

RECENT FINDINGS

A literature search was performed with emphasis on (1) medical imaging studies that assess pelvic floor muscle architecture, (2) subject-specific computational modeling studies that address new topics such as modeling muscle contractions, and (3) pelvic floor neurophysiology studies that report novel devices or findings such as high-density surface electromyography techniques. We found that recent computational modeling studies are featured with more realistic soft tissue constitutive models (e.g., active muscle contraction) as well as an increasing interest in simulating surgical interventions (e.g., artificial sphincter). Diffusion tensor imaging provides a useful non-invasive tool to characterize pelvic floor muscles at the microstructural level, which can be potentially used to improve the accuracy of the simulation of muscle contraction. Studies using high-density surface electromyography anal and vaginal probes on large patient cohorts have been recently reported. Influences of vaginal delivery on the distribution of innervation zones of pelvic floor muscles are clarified, providing useful guidance for a better protection of women during delivery. We are now in a period of transition to advanced diagnostic and predictive pelvic floor medicine. Our findings highlight the application of diffusion tensor imaging, computational models with consideration of active pelvic floor muscle contraction, high-density surface electromyography, and their potential integration, as tools to push the boundary of our knowledge in pelvic floor support and better shape current clinical practice.