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, FVC4peak 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.

Pelvic floor muscle activity patterns in women with and without stress urinary incontinence while running.

BACKGROUND: High-impact activities are often related to urine leakage in women, so deeper insight into continence mechanisms of pelvic floor muscles (PFMs) while running is needed. Therefore, simultaneous information about the intensity of PFM muscle activity and fibre recruitment behavior at each time point of the gait cycle can help in understanding PFM activity patterns. OBJECTIVE: We aimed to analyse spectral changes of the pre- and post-initial contact phase during running at 3 different speeds and to compare women with stress urinary continence (SUI) to those without SUI by using a wavelet approach. METHODS: PFM electromyography (EMG) was recorded during 7, 11 and 15km/h treadmill running and analysed with Morse wavelets. The relative distribution of power was extracted during 6 time intervals of 30ms, from 30ms before to 150ms after initial contact. RESULTS: We included 28 women without SUI (mean [SD] age 38.9 [10.3] years) and 21 with SUI (mean age 46.1 [9.9] years). The groups did not differ in power spectra for each time interval. However, we found significantly less EMG intensity in the lower frequency bands but more intensity in the higher frequency bands in the pre-initial contact phase than at post-initial contact. CONCLUSION: Morse wavelets could be used to extract differences between pre- and post-initial contact activation behavior of PFMs during different running speeds as well as spectral changes toward high or low frequencies. This information sheds light on specific differences in involuntary reflexive activation patterns while running. Muscular preparation and adaptation a few milliseconds before initial contact could be helpful.

Pelvic floor muscle displacement during jumps in continent and incontinent women: An exploratory study.

INTRODUCTION: The prevalence of stress urinary incontinence during high-impact activities is high. Enhanced comprehension of pelvic floor muscle (PFM) displacement and activity is clinically relevant for the development of specific approaches in rehabilitation. The aim of the study is to investigate and to compare PFM displacement between the continent and incontinent women during jumps. METHODS: A cross-sectional, exploratory design was applied to investigate PFM displacement during drop jumps (DJ) and countermovement jumps (CMJ). PFM displacement was assessed in craniocaudal translation and forward-backward rotation with an electromagnetic tracking system. RESULTS: Twenty-eight continent and 22 incontinent women were included. During the first landing of DJ, a primary caudal, during the second landing of DJ/CMJ a primary cranial translation and during all jump a primary backward rotation was observed. No significant difference between the groups was found. DISCUSSION: PFM displacement during running demonstrated caudal translation/forward rotation before and cranial translation/backward rotation after heel strike. During the second landing of DJ/CMJ a cranial translation/backward rotation and during the first landing of DJ a caudal translation/backward rotation has been observed after ground contact. This may be due to the longer lasting bodyweight force in the first landing of DJ. No eccentric-concentric stretch-shortening cycle could be seen. CONCLUSION: This study indicates that during jumps two opposite reactions of involuntary PFM displacement happen, but no stretch-shortening cycle with an eccentric-concentric contraction could be found. Jumping stimuli inducing involuntary PFM displacement should be used for future investigations to consider a beneficial effect concerning continence.

Reliability and validity of pelvic floor muscle displacement measurements during voluntary contractions.

INTRODUCTION AND HYPOTHESIS: Understanding the functioning of pelvic floor muscles (PFM) is crucial in female PFM rehabilitation. The aim of this study was to determine the intra-session retest reliability and validity to evaluate the quantity of PFM displacement. METHODS: This cross-sectional observational study examined the PFM displacement of 17 young healthy nulliparous women in the midsagittal plane. Three maximal voluntary contractions (MVCs) and five fast voluntary contractions (FVCs) were simultaneously examined with an electromagnetic tracking system (ETS) and transabdominal ultrasound (TAUS) and expressed in millimeters (mean, SD). To evaluate reliability and validity, the analysis of variance, intraclass coefficient (2,1), standard error of measurement (SEM), and minimal detectable difference (MDD) were calculated. RESULTS: Maximal voluntary contractions and FVCs in supine position measured by an ETS (TAUS) showed a displacement of MVC: 3.5 ± 1.9 mm (7.8 ± 4.5 mm), FVC: 3.5 ± 2.4 mm (7.6 ± 5.3 mm), and during standing of MVC: 5.2 ± 1.6 mm (9.4 ± 3.8 mm) and FVC: 4.8 ± 2.5 mm (9.7 ± 4.1 mm). Intraclass correlation for the ETS (TAUS) measurement varied between 0.79 and 0.89 (0.61 and 0.74), SEM 0.52 and 1.03 mm (1.54 and 3.2 mm), and MDD 1.54 and 3.2 mm (6.64 and 7.53 mm). The correlation between an ETS and TAUS varied between 0.53 and 0.67. CONCLUSIONS: For MVC and FVC, ETS measurements are highly reliable and TAUS measurements are moderately reliable for both contraction types. The correlation between the TAUS and ETS measurements is moderate. An ETS seems to be a reliable and valid measurement tool for evaluating PFM displacement during voluntary contractions. In future studies, the reproducibility and validity of ETS measurements need to be investigated in impact activities.

Pelvic floor muscle activity during fast voluntary contractions in continent and incontinent women.

AIMS: Stress urinary incontinence (SUI) has also been attributed to a lower speed of contraction of the pelvic floor muscles (PFM). Therefore, PFM assessment and training implement fast voluntary contractions (FVC). The purpose of the study was to explore FVC regarding feasibility, on-/offset and rate of activity determination, as well as differences between continent (CON) and stress urinary incontinent (SUI) women. METHODS: Fifty women were included and examined by means of PFM EMG during rest, maximum voluntary contractions (MVC), and five FVC. MVC-peak activity was used to normalize EMG-data. On-/offset of muscle activity was determined as mean of rectified rest activity plus 1 standard deviation. Linear regression was calculated for rate of activity from onset to peak, peak to offset, and within 200 ms after both onset and peak. Peak activity and time variables related to onset, peak, and offset were calculated. RESULTS: On-/offsets were evaluable for 234/222 of 250 FVC by a computer-based algorithm, 16/28 on-/offsets had to be determined manually. There was no significant difference between groups (CON/SUI) regarding FVC peak (92.1/99.3 %MVC), time to peak (514.2/525.6 ms), and increase of activity (182.8/182.1 %MVC/s). The SUI group showed a significantly slower activity decrease (-120.7/-74.4 %MVC/s). CONCLUSIONS: FVC analyses were shown to be feasible. The significant difference observed between the groups did not refer to activity increase but instead to a prolonged relaxation phase in the SUI group. This prompts to reconsider the interpretation of FVC in PFM testing and training.

Induction of Paracrine Signaling in Metastatic Melanoma Cells by PPARγ Agonist Rosiglitazone Activates Stromal Cells and Enhances Tumor Growth.

In addition to improving insulin sensitivity in type 2 diabetes, the thiazolidinedione family of compounds and the pharmacologic activation of their best-characterized target PPARγ have been proposed as a therapeutic option for cancer treatment. In this study, we reveal a new mode of action for the thiazolidinedione rosiglitazone that can contribute to tumorigenesis. Rosiglitazone activated a tumorigenic paracrine communication program in a subset of human melanoma cells that involves the secretion of cytokines, chemokines, and angiogenic factors. This complex blend of paracrine signals activated nonmalignant fibroblasts, endothelial cells, and macrophages in a tumor-friendly way. In agreement with these data, rosiglitazone promoted human melanoma development in xenografts, and tumors exposed to rosiglitazone exhibited enhanced angiogenesis and inflammation. Together, these findings establish an important tumorigenic action of rosiglitazone in a subset of melanoma cells. Although studies conducted on cohorts of diabetic patients report overall benefits of thiazolidinediones in cancer prevention, our data suggest that exposure of established tumors to rosiglitazone may be deleterious.Significance: These findings uncover a novel mechanism by which the thiazolidinedione compound rosiglitazone contributes to tumorigenesis, thus highlighting a potential risk associated with its use in patients with established tumors. Cancer Res; 78(22); 6447-61. ©2018 AACR.

Pelvic floor muscle activity during jumps in continent and incontinent women: an exploratory study.

PURPOSE: Stress urinary incontinence (SUI) symptoms can be provoked during impact loads such as vertical jumps. To investigate and compare pelvic floor muscle (PFM) activity in women with SUI and continent women (CON) during drop jumps (DJ) and counter movement jumps (CMJ) could clarify the activity of the PFMs during impact loads. METHODS: A tripolar vaginal probe was used to record surface electromyographic (EMG) activity of the PFMs during DJ and CMJ. Time intervals of 30 ms were used to parameterize data from 30 ms before (pre-activity) to 150 ms after (reflex activity) ground contact on a force plate during the landing and take-off phase. EMG signals were normalized to the mean of the peak values of two maximal voluntary contractions (MVC) and expressed in percentage (% MVC). RESULTS: For all time intervals during the landing and take-off phase, no statistically significant differences could be found between women with SUI and CON. EMG values exceeded 100% MVC for all time intervals during all landing and take-off phases. Maximal PFM activation was measured during the first landing of DJ and was 404.1% MVC for SUI and 370.2% MVC for CON. CONCLUSIONS: Vertical jumps seem to stimulate pre-activity before and reflex activity after ground contact during the landing phase and activate PFMs up to 400% MVC. Jumping stimuli inducing involuntary PFM contraction could show a beneficial factor to be integrated in a PFM rehabilitation program.

Pelvic floor muscle activity during impact activities in continent and incontinent women: a systematic review.

INTRODUCTION AND HYPOTHESIS: Investigating the activity of the pelvic floor muscles (PFMs) in women during impact activities such as jumping, running or coughing may elucidate different aspects of PFM activation and therefore clarify the pathophysiology of stress urinary incontinence (SUI). A systematic review (PROSPERO 2016:CRD42016035624) was conducted to summarize current evidence on PFM activity during impact activities in both continent and incontinent women. METHODS: PubMed, EMBASE, Cochrane, and SPORTDiscus databases were systematically searched for studies published up to December 2016. The PICO approach (patient, intervention, comparison, outcome) was used to construct the search queries. Original studies were included that investigated PFM activity during impact activities if they included terms related to muscle activity and measurement methods, test positions, activities performed and continence status. Two reviewers screened titles and abstracts independently to ascertain if the included studies fulfilled the inclusion criteria, and extracted data on outcome parameters. RESULTS: The search revealed 28 studies that fulfilled the inclusion criteria, of which 26 were cross-sectional studies. They used different electromyography measurement methods, test activities, test positions, and comparisons with other structures. Ten studies compared continent and incontinent women. The timing of PFM activity in relation to the activity of other trunk muscles seems to be a crucial factor in maintaining continence. Women with SUI have delayed PFM activity. CONCLUSIONS: The findings of this systematic review suggest that impact activities causing involuntary and reflex PFM activity should be the subject of further study. This may help guide clinical studies to improve our understanding of how the PFMs react during impact activities and to determine best practices that can be included in rehabilitation programmes.

Evaluation of pelvic floor kinematics in continent and incontinent women during running: An exploratory study.

AIMS: Impact activity like running is associated with an increase in intra-abdominal pressure which needs to be sufficiently countered by pelvic floor muscle (PFM) activity to secure continence. The aim of this study was to investigate and compare PFM kinematics in continent and incontinent women during running. METHOS: Three-dimensional position and orientation was measured with the electromagnetic tracking device trakSTAR™. One sensor was attached to the vaginal probe and a second one was secured to the subjects' skin at the height of the second sacral vertebrae. Cranial-caudal and forward-backward displacement of the vaginal probe was measured during 10 sec running on a treadmill at the speeds 7, 11, and 15 km/h. Displacement data from 100 ms before to 300 ms after heel-strike were analyzed. RESULTS: Nineteen incontinent and twenty-seven continent women were included in this study. Before the foot touched the ground caudal translation and forward rotation of the vaginal probe was detected, whereas after heel-strike a cranial translation and backward rotation was measured. Cranial-caudal translation as well as backward-forward-rotation did not differ significantly between continent and incontinent subjects for the three speeds. Analysis of maximum displacements showed significantly increasing displacement with increasing speeds. CONCLUSIONS: Kinematic measurements during impact activity of running demonstrated caudal translation before and cranial translation after heel-strike. The hypothesis of caudal translation through impact activity was not confirmed. Patterns seem similar between continent and incontinent subjects. Associations between the direction of displacement and muscle action of PFMs remain assumptions.

Evaluation of pelvic floor muscle activity during running in continent and incontinent women: An exploratory study.

AIMS: Impact activities like running are known to elicit symptoms of stress urinary incontinence (SUI). The aim of this study was to investigate and compare pelvic floor muscle activity in continent and SUI women during running at three different speeds and thereby elucidate contraction characteristics of the pelvic floor during impact. METHODS: Surface electromyographic (EMG) activity from the pelvic floor muscles during running on a treadmill was recorded with a tripolar vaginal probe. EMG was measured during 10 s at the speeds 7, 11, and 15 km/h. Data from 30 ms before to 150 ms after heel-strike were parameterised to time intervals of 30 ms. The reference value set as 100% for EMG normalisation was calculated as the mean of the peak values of two maximum voluntary contractions. RESULTS: No statistically significant differences between continent and incontinent subjects could be found for the EMG values for all time intervals. Mean EMG pre-activity and reflex activity increased significantly with speed (P < 0.05). Mean EMG activity during running was significantly above PFM onset activation. Values in women with SUI exceeded 100 %MVC for all time intervals at the highest speed of 15 km/h. CONCLUSIONS: Running appears to trigger pre-activation before and reflex-activation after heel-strike and should therefore not only be regarded with caution due to its SUI related effects. Running training stimuli may serve as a beneficial complement to a PFM training rationale, leading to reflex activity of the pelvic floor muscles, when used in sense of power training methodology.

Pelvic floor muscle displacement during voluntary and involuntary activation in continent and incontinent women: a systematic review.

INTRODUCTION: Investigations of the dynamic function of female pelvic floor muscles (PFM) help us to understand the pathophysiology of stress urinary incontinence (SUI). Displacement measurements of PFM give insight into muscle activation and thus help to improve rehabilitation strategies. This systematic review (PROSPERO 2013: CRD42013006409) was performed to summarise the current evidence for PFM displacement during voluntary and involuntary activation in continent and incontinent women. METHODS: MEDLINE, EMBASE, Cochrane and SPORTDiscus databases were searched using selected terminology reflecting the PICO approach. Screening of Google Scholar and congress abstracts added to further information. Original articles investigating PFM displacement were included if they reported on at least one of the aims of the review, e.g., method, test position, test activity, direction and quantification of displacement, as well as the comparison between continent and incontinent women. Titles and abstracts were screened by two reviewers. The papers included were reviewed by two individuals to ascertain whether they fulfilled the inclusion criteria and data were extracted on outcome parameters. RESULTS: Forty-two predominantly observational studies fulfilled the inclusion criteria. A variety of measurement methods and calculations of displacement was presented. The sample was heterogeneous concerning age, parity and continence status. Test positions and test activities varied among the studies. CONCLUSIONS: The findings summarise the present knowledge of PFM displacement, but still lack deeper comprehension of the SUI pathomechanism of involuntary, reflexive activation during functional activities. We therefore propose that future investigations focus on PFM dynamics during fast and stressful impact tasks.