Objective: There is preliminary evidence linking long-term participation in high-impact exercise with poor performance in labor and increased incidence of stress urinary incontinence, which may be due to altered pelvic floor function. Recent work has shown that HIFIT (high-impact, frequent intense training) athletes have an increased cross-sectional area of the levator ani muscle group as visualized using magnetic resonance imaging (MRI). The aim of this study was to further characterize pelvic floor muscle function and pelvic organ descent in a nulliparous athletic population and compare it with non-athletic controls matched for age and body mass index, using three-dimensional/four-dimensional (3D/4D) pelvic floor ultrasound imaging.
Methods: In this prospective comparative study translabial ultrasound imaging was used to assess pelvic floor anatomy and function in 46 nulliparous female volunteers (aged 19-39 years), 24 HIFIT and 22 controls. Two-dimensional (2D) and 3D translabial ultrasonography was performed on all subjects, after voiding and in the supine position. Descent of the pelvic organs was assessed on maximum Valsalva maneuver, whilst volume datasets were acquired at rest, during pelvic floor muscle contraction and during a Valsalva maneuver. Participants performed each maneuver at least three times and the most effective was used for evaluation.
Results: HIFIT athletes showed a higher mean diameter of the pubovisceral muscle (0.96 cm vs. 0.70 cm, P < 0.01), greater bladder neck descent (22.7 mm vs. 15.1 mm, P = 0.03) and a larger hiatal area on Valsalva maneuver (21.53 vs. 14.91 cm(2), P = 0.013) compared with the control group. There were no significant differences in hiatal area at rest or on maximal voluntary contraction between the two groups.
Conclusion: HIFIT athletes show significant differences in several of the measured parameters for both function and anatomy of the pelvic floor. Further research into the impact of this altered function on childbirth and continence mechanisms is needed.