Women with stress urinary incontinence demonstrate motor control differences during coughing

This study compared the patterns of pelvic floor muscle (PFM) activity during coughing between women with stress urinary incontinence (SUI) and continent women, using surface electromyography (EMG) and posterior vaginal wall (PVW) pressure.

Twenty-four women participated: eight continent, eight with mild SUI and eight with severe SUI. Volunteers performed three maximum coughs in supine and standing. Maximum PFM EMG and PVW pressure amplitudes and the timing of the EMG peak relative to the PVW pressure peak were determined. Ensemble average PVW pressure versus EMG curves were created.

There were no significant differences among the groups in the maximum EMG or PVW pressure amplitudes. The EMG and PVW pressure peaked simultaneously in both positions in the continent group. In the mild SUI group, the EMG and PVW pressure peaked simultaneously in supine, but the EMG peaked before the PVW pressure in standing. In the severe SUI group, the EMG peaked before the PVW pressure in both positions. The shapes of the PVW pressure versus EMG curves were similar among the groups and positions, however the SUI groups displayed higher EMG-intercepts than the continent women.

These findings suggest that urine leakage during coughing in women with SUI may be related to delays in force generation rather than PFM weakness.