Activity of deep and superficial pelvic floor muscles in women in response to different verbal instructions: a preliminary investigation using a novel electromyography electrode
Journal Publication ResearchOnline@JCUAbstract
Introduction: Verbal instructions are used clinically to encourage activation of the pelvic floor muscles (PFM). Whether separate layers of PFM activate differently in response to instructions remains unknown. Aim: To test the hypotheses that (i) instructions that aimed to bias activity of a specific muscle layer would increase activation of the targeted layer to a greater extent than the other layer, (ii) activity of individual PFM layers would differ between instructions, and (iii) PFM activity would be symmetrical for all instructions. Method: PFM electromyography (EMG) was recorded using custom-designed surface electrodes in 12 women without PFM dysfunction. The electrode included 4 pairs of recording surfaces orientated to measure EMG from deep and superficial PFM on each side. 3 submaximal contractions were performed for 5 seconds in response to 7 verbal instructions. Root-mean-squared EMG amplitude was calculated for 1 second during the period when participants most closely matched the target activation level. A repeated-measures anova was used to test whether PFM EMG differed between instructions and between regions. The EMG increase of individual muscles relative to that of the reference muscle [deep/right PFM] was compared to no change with t-tests for single samples. Main Outcome Measure: PFM EMG amplitude. Results: Superficial PFM EMG was greater than deep PFM for all instructions (P = .039). 2 instructions induced the greatest amplitude of EMG for the superficial PFM: “squeeze the muscles around the vaginal opening as if to purse lips of your mouth” and “draw the clitoris in a posterior direction” (P = .036). Asymmetry was found in the deeper PFM in 3 instructions designed to bias the superficial PFM. Strength & Limitations: This preliminary study recorded activation of deep and superficial PFM layers in females with a custom-designed novel electrode. Some cross-talk of recording between muscle layers is possible but unlikely to impact the major findings. Conclusion: Verbal instructions used to teach PFM contractions can influence their pattern of activity. This study provides preliminary evidence that, in a selection of verbal instructions, the superficial PFM activates more than the deep PFM, and that the deep PFM can have asymmetrical activation.
Journal
Journal of Sexual Medicine
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Volume
16
ISBN/ISSN
1743-6109
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Issue
5
Pages Count
7
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Publisher
Elsevier
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DOI
10.1016/j.jsxm.2019.02.008