Force development in pelvic floor muscles increased as a function of vaginal diameter when measured in the frontal plane. The measurements were reliable at all the different diameters chosen.

Muscular fatigue, defined as rate of force loss, does not seem to be associated with urinary stress incontinence. Moreover, muscular activity recruitment patterns were equal in both groups suggesting that other factors than disturbances of ordered muscle recruitment, that is, pelvic floor followed by abdominal muscles, may be responsible for stress urinary incontinence. It is likely that reduced normalized force, as found in the incontinent group, is an important contributing factor.

This study indicates that both active force development and active stiffness in the pelvic floor tissues are significantly reduced in incontinent women, whereas the passive resting mechanical forces in the pelvic floor tissues in both groups are not different.

Our study supports the idea that in general practice, or in rather unselected patients, women with urinary incontinence may be classified and treated without urodynamic examination. If there is little or no improvement during the first few months referral should be considered, and this should be done sooner for patients with severe incontinence or prior gynecological operations than for other patients.

Women 50 to 74 years of age with urinary incontinence may improve considerably through conservative treatment in general practice.