Pelvic floor muscle activity in different sitting postures in continent and incontinent women

Objective: To determine whether resting activity of the pelvic floor muscles (PFMs) and abdominal muscles varied in different sitting postures in parous women with and without stress urinary incontinence (SUI). Design: PFM and abdominal muscle activity was recorded in 3 sitting postures: slump supported, upright unsupported, and very tall unsupported. Spinal Curves were measured in Slump Supported and upright unsupported. Setting: A research laboratory. Participants: Women (N= 17) with a history of vaginal delivery, 8 who were symptomatic of SUI and 9 who were asymptomatic. Interventions: Not applicable. Main Outcome Measures: Electromyographic activity of (1) the resting PFM recorded per vaginam with Surface electrodes and (2) superficial abdominal muscles using surface electrodes. Changes in spinal curves were measured with a flexible ruler. Results: Electromyographic activity of the PFM increased significantly from slump supported to upright unsupported postures in both groups (P<.001) but with lower levels of activity in women with SUI (P<.05). PFM activity increased further in very tall unsupported sitting in comparison with slump supported sitting (P<.001). Obliquus internus abdominis electromuyographic activity was greater in upright Unsupported than in slump supported sitting (P<.05), and electromyographic activity of other abdominal muscles was greater in very tall Unsupported than slump Supported. Women with SUI had a trend for greater activity in the abdominal Muscles in upright unsupported than asymptomatic women. Asymptomatic women had a greater depth Of lumbar lordosis in upright unsupported sitting than women with SUI (P=.04). Conclusions: More upright sitting postures recruit greater PFM resting activity irrespective of continence status. Further investigation should consider the effect of sitting posture in rehabilitation.