Submaximal pelvic floor muscle contractions: similar bladder-neck elevation, longer duration, less intra-abdominal...

An adequate pelvic floor muscle contraction (PFMC) elevates the bladder neck (BN) and stabilizes it during increased intra-abdominal pressure (IAP). A maximal PFMC may increase the IAP and thereby prevent BN elevation. The aim of this study was to assess BN elevation during submaximal and maximal PFMC and their achievable duration.

We recruited 68 women with stress urinary incontinence and 14 vaginally nulliparous continent controls who were able to perform a PFMC on vaginal palpation. Women were upright and performed a maximal PFMC as long as possible, followed by a submaximal PFMC, controlled by vaginal electromyogram (EMG). BN position was measured with perineal ultrasound, IAP and urethral pressure with a microtip catheter, and breathing with a circular thorax sensor.

A submaximal PFMC elevated the bladder neck 4 mm in continent and incontinent women (p = 0.655) and 4.5 vs. 5 mm during maximal PFMC (0.528). Submaximal PFMC was maintained significantly longer than a maximal PFMC (33 vs 12 s) with no difference between groups. A maximal PFMC resulted in BN descent in 29% of continent and 28% of incontinent women, which was not observed during submaximal PFMC. Breathing was normal in 70% of continent and 71% of incontinent women during submaximal PFMC but stopped completely in 21 and 50%, respectively, during maximal PFMC (p = 0.011). IAP increase was significantly greater with maximal PFMC in both groups (24 vs. 9.6 cmH₂O and 17 vs. 9 cmH₂O, respectively).

Submaximal PFMC are sufficient to elevate the bladder neck, can be maintained longer, and breathing was not influenced.