Female participation in moderate to heavy strength training has increased with the popularity of current fitness trends. Lifting heavy weight is reported to be a risk factor for the development or worsening of pelvic floor dysfunction, specifically pelvic organ prolapse, due to the effects of intra-abdominal pressure placed upon pelvic support structures. The levator ani muscle provides active and passive support to the pelvic organs, particularly in upright positions against gravity, however structural impairment as a result of a vaginal delivery may increase the risk for pelvic floor dysfunction. The aim of this study was to compare measures of the levator hiatus in a standing position using transperineal ultrasound between vaginally parous females who lift heavy weight and those who are physically active but do not lift heavy weight for exercise.

This preliminary study reports data from an ongoing cross-sectional, observational study. Women who were physical active at least 3 times per week and had at least one vaginal delivery were recruited into two groups; those who lift >80% of their bodyweight for any exercise for at least the previous 6 months (heavy lifters; HL) and those who do not lift >15kg for exercise (non-lifters; NL). Women were excluded if they were pregnant, breastfeeding, had a chronic cough, or had any previous pelvic surgeries. An online survey was completed for demographic information, including the use of the Pelvic Floor Distress Inventory short form questionnaire (PFDI-20). The PFDI-20 question on the sensation of a vaginal bulge was used to suggest the presence of symptomatic pelvic organ prolapse (POP). The question on urine leakage during physical stress was adapted to include “leaking when skipping, jumping or during other exercise” and was used to suggest the presence of stress urinary incontinence (SUI). Three-dimensional (3D) transperineal ultrasound volumes were acquired in supine and a relaxed standing position after bladder emptying using a Voluson i system and a 4-8 MHz RAB convex probe. Volume data were acquired to assess levator hiatal area and AP distance at rest, during a maximal pelvic floor muscle contraction, and during abdominal straining/valsalva (Figure 1). Standing measures were used to observe the natural effects of gravity on levator ani support. Data were analysed using 4D View software by one of the authors, who was blinded to the group. Rendered volumes of 1-2cm thickness in the plane of minimal levator hiatal dimension were used for levator hiatal area measures (1). Levator urethral gap distance in tomographic imaging was used for assessing levator defects. Two-dimensional (2D) images in the midsagittal plane were used to measure levator anteroposterior (LAP) distance from the most inferior margin of the pubic symphysis to the most medial margin of the puborectalis muscle (2). The proportional change in LAP from rest to maximal pelvic floor muscle contraction was calculated by the following formula: 100 x [(LAPrest – LAPcontraction)/LAPrest] (3). Mann Whitney U Test was used to determine differences for continuous measures between HL and NL groups, and Pearson’s Chi-Square test was used for categorical variables. Statistical significance was set at p<0.05. Data are presented as median (IQR), range.

Of the 33 women included, 17 and 16 women were allocated to the NL and HL groups, respectively. There were no significant differences between the two groups for any baseline characteristics. The median age was 39 years in both groups (range, NL 33-55yrs; HL 33-46yrs; p=0.590) and the median BMI was 22.0 kg/m2 in both groups (range, NL 17.8-25.7; HL 20.1-31.5; p=0.425). The median vaginal parity was 2 in both groups (range, NL 1-5; HL 1-4; p=0.503). Two participants in each group reported the use of forceps for a delivery and both groups had a median of 4.00kg for the heaviest baby delivered vaginally (range, NL 3.0-4.3kg; HL 2.3-4.4kg; p=0.134). HL reported a median one-repetition maximum back squat of 68kg (range, 45-130kg). Two NL (11.8%) and one HL (6.25%) participants reported the sensation of a vaginal bulge (p=1.00). Reports of stress urinary incontinence was present in 47.1% of NL as opposed to 56.3% of HL (p=0.269). Four NL were found to have a complete, unilateral levator ani defect, while two in each NL and HL group were found to have a partial, unilateral levator defect (p=0.948). No significant differences between NL and HL were found for levator hiatal area during standing rest (p=0.509), abdominal straining (p=0.914), LAP distance at rest (p=1.00) or maximum pelvic floor muscle contraction (p=0.861) (Figure 2). No significant differences were found between groups for percentage of change in LAP distance from rest to maximal pelvic floor muscle contraction (p=0.711).

This study found that vaginally parous women lifting heavy weight for exercise did not have significantly different levator hiatal measures when comparing median values to physically active women who do not lift heavy weights. Women lifting heavy weights did display a greater range of values for all levator hiatal measures, despite no apparent major levator defects observed.  Individual variation in the complexity of pelvic floor support and symptoms of pelvic organ prolapse most likely play a major role. A larger population is required to confirm these findings.

These preliminary results suggest that some vaginally parous women who lift heavy weights for exercise are able to do so without appearing to have an effect on the deep, supportive pelvic floor musculature to an extent that differs from women who are not lifting heavy weights.

Dietz, H. P., Wong, V. & Shek, K. L. A simplified method for determining hiatal biometry. Australian New Zealand J Obstetrics Gynaecol 51, 540–543 (2011).
Nyhus, M. Ø. et al. Ultrasound assessment of pelvic floor muscle contraction: reliability and development of an ultrasound-based contraction scale. Ultrasound Obst Gyn (2019) doi:10.1002/uog.20382.
Volløyhaug, I., Mørkved, S., Salvesen, Ø. & Salvesen, K. Å. Assessment of pelvic floor muscle contraction with palpation, perineometry and transperineal ultrasound: a cross-sectional study. Ultrasound Obst Gyn 47, 768–773 (2016).