The effect of 3 vibration types on pelvic floor muscles activity

The participants will be randomly allocated to one of three groups based on computer random number generator. Each group will consist of 15 participants. The groups will be homogeneous with respect to age, body weight, height, maximum voluntary pelvic floor muscle contraction (sEMG MVC) and pelvic floor muscle strength (Oxford grading scale score). Methods The study protocol has been approved by the Bioethics Committee. The measurements will be performed under standard testing conditions, the same for all subjects. The bioelectric potential of the muscles (sEMG) will be measured with surface electrodes, and, in the case of pelvic floor muscles, with vaginal probes. Each study participant will be equipped with a personal probe. The probe will be inserted using a small amount of antiallergic lubricant with the sensors positioned laterally in the vagina. Co-activation of the synergistic muscles during voluntary contraction of pelvic floor muscles will also be investigated. Muscle activity will be recorded from the following muscle groups: pelvic floor muscles and synergistic muscles (the rectus abdominis, the gluteus maximus, the transversus abdominis/ internal abdominal oblique muscle, the medial gastrocnemius muscle) All subjects will be instructed on the correct contraction of pelvic floor muscles and will be able to observe sEMG signals on the computer monitor during the instruction session. All sEMG recordings will be performed by the same investigator. The MVC procedures (three 5-second attempts at maximum contraction with a 60 second rest in between): - to recruit pelvic floor muscles in A and B groups - standing position (= testing position, static standing with feet hip-width apart; hip and knee flexion 35°) and in supine lying position (the hip and knee will be positioned at 30° and 90° of flexion, respectively). In group C - MVC will be measured in the testing position (patient’s forearms supported with Redcord slings). - to recruit the rectus abdominis: feet flat secured to the table with a strap; supported sitting in a 30-degree position; the subject’s shoulder girdle strapped to the table; a sit-up attempt. - to recruit the transversus abdominis: supine lying with abdominal hollowing exercises - to recruit the gluteus maximus: prone lying, pelvic girdle strapped to the table, overextension in the hip joint, lower leg secured to the table with the knee in full extension - to recruit the medial gastrocnemius: bench-sitting with resistance against the restrained hip with the knee extended and unilateral plantar flexion at 90° ankle position. A rigid seat belt strap will be placed around the sole of the foot. The aims of the Phase 0 of the study are: 1. Intra- and intersession reliability of sEMG recording during: a/maximum voluntary pelvic floor muscle (PFM) contraction in standing (= testing position) and in supine-lying position b/resting PFM activity in standing (60 seconds) c/60 seconds of synchronous whole-body vibration (Fitvibe 600) of two intensities, d/60 seconds of stochastic resonance whole-body vibration (SRT Zeptor® Medical-plus noise) of two vibration intensities, e/60 seconds of localized vibration, ie., controlled vibration to selected body parts (Redcord Stimula) of two intensities 2.Correlations among synchronous whole-body vibration, stochastic resonance whole-body vibration and localized vibration Phase 0 will consist of: a/ the measurement of the maximal voluntary contraction (MVC) of the investigated muscles (random order) b/ sEMG recording of resting PFM activity in supine lying (60 seconds x 3 trials, in groups A, B and C) c/ sEMG recording of resting PFM activity in standing (60 seconds x 3 trials). Testing position in group A and B: static standing with feet hip-width apart; hip and knee flexion 35°. Testing position in group C: static standing with the participant's forearms supported with Redcord slings. d/ 3 x 60s sEMG recordings during synchronous whole-body vibration with vibration intensity of 30 Hz/2mm and 3 x 60s of 40 Hz/4 mm (group A) (random order). e/ 3 x 60s sEMG recordings during stochastic resonance whole-body vibration of basic frequency 6 Hz/ noise level 2; and 3 x 60s of 12 Hz/ noise level 4 (group B) (random order). f/ 3 x 60s sEMG recordings during vibration applied through the ropes with vibration intensity of 30Hz/ medium amplitude – trim 3 and 50Hz/ high amplitude – trim 5 (group C) (random order). Prior to Phase 0, all subjects will be instructed on the correct contraction of the pelvic floor muscles and will be able to observe sEMG signals on the computer monitor during the instruction session. The study procedure (MVC, resting activity in supine and standing positions, 3 x 60s sEMG recordings during vibration) will be repeated after one-hour rest (with vaginal electrode and surface electrodes in place) in order to assess inter-trial reliability. It will also be repeated during the follicular phase of the next menstrual cycle of each study participant to assess inter-day reliability. The aims of the phase 1 of the study are: 1. to compare the effect of different intensity synchronous whole-body vibration (Fitvibe 600), stochastic resonance whole-body vibration (SRT Zeptor® Medical-plus noise) and localized vibration, ie., controlled vibration to selected body parts (Redcord Stimula) on reflex activity of pelvic floor muscles 2. to determine the effect of the above vibration methods on the sEMG amplitude of voluntary pelvic floor muscle contractions. Phase 1 will consist of: Stage 1 - control phase in group A - synchronous whole-body vibration (WBV) Testing position: static standing with feet hip-width apart; hip and knee flexion 35 degree a/ sEMG recording of MVC PFM in standing (= testing position) b/ sEMG recording of resting PFM activity in standing (10 seconds) c/ sEMG recording of two quick-flick contractions and two 10s-contractions in standing d/ sEMG recording – vibration switched off – standing position (60 seconds) e/ sEMG recording – immediately after the 60second non-vibration standing – two quick-flick contractions, two 10 second contractions, 10 second relaxation period Stage 2 - intervention phase Testing position: static standing on the vibration platform with feet hip-width apart; hip and knee flexion 35 degree 60 second sEMG recordings during synchronous whole-body vibration of 6 different vibration intensities (random order): 20 Hz/2mm, 20 Hz/ 4 mm, 30 Hz/ 2mm, 30 Hz/ 4 mm, 40 Hz/ 2 mm and 40 Hz/ 4 mm, Stage 3 sEMG recording immediately after each of the 60s vibration intensities. After stepping off the platform, resting PFM activity as well as PFM activity during two quick-flick contractions and two 10 second contractions will be recorded (standing position). All measurements will be performed on the same day. Stage 1 - control phase in group B - stochastic resonance whole-body vibration (ST): Testing position: static standing with feet hip-width apart – each foot on one of the plates; hip and knee flexion 35 degree a/ sEMG recording of MVC PFM in standing (=testing position) b/ sEMG recording of resting PFM activity in standing (10 seconds) b/ sEMG recording of resting PFM activity in standing (10 seconds) c/ sEMG recording of two quick-flick contractions and two 10 second contractions in standing d/ sEMG recording – vibration switched off – standing position (60 seconds) e/ sEMG recording – immediately after the 60 second non-vibration standing – two quick-flick contractions, two 10s contractions, 10s relaxation period Stage 2 - intervention phase Testing position: static standing with feet hip-width apart – each foot on one of the plates; hip and knee flexion 35 degree 60s sEMG recordings during stochastic resonance whole-body vibration of 6 different vibration intensities (random order): Basic frequency: 6 Hz/ noise level 2; 6 Hz/ noise level 4; 10 Hz/ noise level 2; 10 Hz/ noise level 4; 12 Hz / noise level 2; 12 Hz/ noise level 4. Stage 3 sEMG recording immediately after each of the 60s stochastic resonance vibration intensities. After stepping off the platform, resting PFM activity as well as PFM activity during two quick-flick contractions and two 10s-contractions will be recorded (standing position). All measurements will be performed on the same day. Stage 1 - control phase in group C – vibration applied through the ropes of the Redcord Stimula Testing position: static standing with the participant's forearms supported with Redcord slings a/ sEMG recording of MVC PFM in testing position b/ sEMG recording of resting PFM activity in testing position (10 seconds) - the participant's forearms supported with Redcord slings c/ sEMG recording of two quick-flick contractions, two 10 second contractions d/ sEMG recording – vibration switched off; testing position (60 seconds) e/ sEMG recording – immediately after the 60 second non-vibration recording – two quick-flick contractions, two 10 second contractions, 10 second relaxation period Stage 2 – intervention phase 60s sEMG recordings during Redcord Stimuli vibration of 6 different intensities (random order): 30Hz / trim 3; 30Hz/ trim 5 40 Hz/ trim 3; 40Hz/ trim 5 50 Hz/ trim 3; 50Hz/ trim 5 Stage 3 sEMG recording immediately after each of the 60 second Redcord Stimuli vibration intensities. After stepping off the platform, resting PFM activity as well as PFM activity during two quick-flick contractions and two 10s-contractions will be recorded. Each vibration will last 60 seconds with a 10-minute break between subsequent applications. All measurements will be performed on the same day.