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Koenig I.1,2, Blasimann A.1, Hauswirth A.1, Eichelberger P.1, Baeyens J.-P.2, Radlinger L.1
1Bern University of Applied Sciences, Health, Physiotherapy, Bern, Switzerland, 2Vrije Universiteit Brussel, Faculty of Physical Education and Physiotherapy, Brussel, Belgium
Background: Pelvic floor muscles (PFM) must be able to contract reflexively given that sneezing and coughing provoke an expeditious intra-abdominal increase in pressure, whereupon PFM must react. Furthermore, reflex activity is also needed during whole body movements with a high impact load such as running or jumping. Consequently, a better understanding of muscle fiber recruitment and the timing of PFM contraction would support the understanding of how PFM function contribute to continence. PFM electromyography (EMG) is a commonly used method to assess PFM function. Conventional EMG analyses of rectified signals or root mean squared values provide information about timing and intensity of muscle activity without considering frequency components. The gain of a wavelet approach is to provide simultaneous information in the domains of time, frequency and magnitude.
Purpose: This systematic literature review regarding wavelet functions to analyze EMG muscle activity patterns of the lower extremity (or PFM if available) during walking or running will help find an appropriate wavelet application to analyze PFM EMG patterns derived from women performing dynamic impact activities in further studies.
Methods: This systematic review is listed in the international prospective register of systematic reviews (PROSPERO) with the identification number CRD42016035986. The composition was based on the PICO model and the PRISMA checklist. Eleven relevant electronic databases were systematically searched until March 28th 2016. Additionally, congress proceedings as well as reference lists were scanned. The quality of the included studies and the risk of bias were analyzed with The Cochrane Collaboration`s tool for assessing risk of bias. The following data were extracted: first author, year, subject characteristics, intervention, outcome measures & variables, results and wavelet specification.
Results: In this review, 20 studies were included. In 18 studies EMG activity patterns of the lower extremities were investigated. Furthermore, two conference proceedings analyzing PFM were found. The included studies analyzed three different main objectives: The recognition rate, time period characteristics and fiber recruitment patterns. The recognition rate of the EMG of muscles of the lower extremity varied between 68.4% and 100%. However, the rate of false discrimination was 4% discriminating maximum voluntary contraction of healthy from weak PFM. The evaluation of muscle timing, time shifts and early or delayed muscle activation showed differences in the activation patterns of walking compared to running, as well as healthy people compared to patients. Atrophic muscles did not produce the high frequency type II fiber components but more energy in their lower frequencies.
Conclusion(s): Wavelets reflect signal components related to activities of slow type I fibers, fast type II firing rate fibers and also muscle timing characteristics. This information is needed to support the understanding of how PFM dysfunction contributes to incontinence regarding pre-activation and reflex circles. Therefore, a wavelet approach is appropriate for PFM EMG analysis.
Implications: Although wavelet analysis is well established in the field of biomechanics, only two conference proceedings were found analyzing PFM EMG with wavelets. However, this knowledge would allow optimizing the training protocols of PFM rehabilitation. Therefore, PFM EMG wavelet analysis while running will be performed in future projects.
Funding acknowledgements: None. We declare that we have no conflict of interest and no affiliations to disclose.
Topic: Women's & mens pelvic health
Ethics approval: For this type of study formal consent is not required.
All authors, affiliations and abstracts have been published as submitted.
