More than one adult in every hundred has problems with controlling their bowels and experiences bowel incontinence. This extremely embarrassing and socially restricting problem often results from damage to or weakness of the muscles around the back passage (the "anal sphincter muscle"). This can be because of childbirth, chronic straining, or sometimes for no apparent reason. It is known that electrical stimulation helps people with bladder control problems (urinary incontinence), but it has never been properly tried with people with bowel problems. This study will scientifically evaluate whether electrical stimulation can increase the strength of the anal sphincter muscle and thus improve bowel control.