Contraction of the pelvic floor muscles during abdominal maneuvers

(A) Placement of vaginal and anal electromyographic electrodes. Electrodes were situated on either side of the intravaginal probe and anal electrodes were adhered to the right and left anal wall (only the left anal electrode is shown). (B) Placement of vaginal and anal pressure probes. (C) Recordings of electromyographic activity of the hip adductor and gluteus maximus along with concurrent recordings from the anal and vaginal electrodes.

Relation between anal and gastric pressures. (A) Maximal pelvic floor contraction. (B) Strong abdominal muscle contraction. Pressures are shown during contractions of the abdominal and pelvic floor muscles. The data suggest that the pressure recordings were independent, and thus the pelvic pressure were not simply due to transmitted pressure from the abdominal cavity.

Abdominal muscle activity during the experimental tasks in supine. Abdominal (Abd) muscle activity with each level of contraction are shown as (A) the mean change in width recorded using ultrasound, (B) mean change in electromyographic activity for all subjects recorded with surface electromyography (Abd) and with fine-wire electrodes for 1 subject (TrA, OI, OE), and (C) raw electromyographic data recorded with fine-wire electrodes (n = 1). (B) surfaceelectro myographic electrodes, and (C) and fine-wire electromyographic electrodes (n = 1) (B & C) are shown. (B) Gastric pressure recorded with each abdominal contraction are also shown (n = 2). (A) The inset shows the method for measurement of muscle width on the ultrasound image of the lateral abdominal wall. Activity was increased in the strong condition, but there was no difference between the gentle and moderate conditions.

Electromyographic activity of the pelvic floor and abdominal muscles with abdominal and pelvic floor muscle contractions. The representative raw electromyography shows that activity of the pelvic floor muscles accompanied all levels of abdominal muscle activity. Abbreviation: Abd, abdominal muscle.

Mean change in pelvic floor response with abdominal muscle contraction. Mean (A) electromyographic and (B) pressure data for the group are shown normalized to the amplitude recorded with the maximal contraction of the pelvic floor muscles. Abbreviations: AP, anal pressure; VP, vaginal pressure.

Pelvic floor pressures and abdominal muscle electromyography with abdominal and pelvic floor muscle contractions. The representative data (same subject as fig 4) shows that activity of the pelvic floor muscles accompanied all levels of abdominal muscle activity.

Latency between onsets of the increase in gastric and pelvic floor pressures. Representative (A) raw data and (B) data from single subjects are presented. The raw data in A show an increase in anal pressure of almost 500ms before an increase in gastric pressure. (B) All onsets of vaginal and anal pressure are shown relative to the onset of the gastric pressure increase at zero.

Mean change in pelvic floor muscle electromyography with abdominal contraction in standing position. Data are presented with subjects standing in (A) neutral and (B) with slight lumbar flexion.