Pelvic floor muscle length changes with breathing in males: a preliminary report.

The study aimed to identify whether pelvic floor muscles modulate length with breathing, and if any length changes induced by breathing relate to abdominal cavity displacement and intra-abdominal pressure. To investigate these relationships, displacement of pelvic landmarks that related to pelvic floor muscle length using transperineal ultrasound imaging, breath volume, intra-abdominal pressure, abdominal and ribcage displacement, and abdominal and anal sphincter muscle electromyography were measured during quiet breathing and breathing with increased dead-space in ten healthy men. Pelvic floor muscle landmark displacement modulated with ribcage motion during breathing. This relationship was stronger for: i) motion of the urethrovesical junction (puborectalis muscle length change) than the mid-urethra landmark (striated urethral sphincter muscle length change), and ii) dead-space breathing in standing than dead-space breathing in supine or quiet breathing in standing. In most (but not all) participants, the urethrovesical junction descended during inspiration and elevated during expiration. Striated urethral sphincter length changes during the respiratory cycle was independent of intra-abdominal pressure. In summary, breathing involves pelvic floor muscle length changes and is consistent with the role of these muscles during respiration to aid maintenance of continence, lung ventilation and/or provision of support to the abdominal cavity. Clinicians who train pelvic floor muscles need to be aware that length change of pelvic floor muscles is expected with breathing.