Strength training, including heavy weight lifting,  is increasingly popular among women. A recent study (1) found that young strength- and weightlifters reported high prevalence of pelvic floor disorders (PFD) with urinary incontinence (UI); 50%, anal incontinence 80% and pelvic organ prolapse 23 %. Pre-contraction of the pelvic floor muscles (PFM) before and during increases in intra-abdominal pressure (IAP) has shown to prevent UI in the general population, but the effect of this manoeuvre has not been investigated during strenuous strength exercises (2). The aims of the present study were to investigate: 1. feasibility of using femfit® to measure IAP and PFM response during four strenuous strength exercises and 2. if a pre-contraction of the PFM can exceed increases in IAP during strenuous strength exercises.

A short-term, experimental design was used to answer the research questions. The participants were tested in squat, deadlift, leg press, and curl up, performed in random order with and without pre-contraction of the PFM. Inclusion criteria: active women between 18 and 35 years performing strength training ≥ once/week and able to lift their own body weight for two repetitions in the four exercises. Exclusion criteria: Pregnancy,  inability to contract the PFM, injuries or surgeries which could affect participation. The study is exploratory and a priori power calculation was not conducted. The participants answered a questionnaire on background variables and PFD. Assessment of ability to contract the PFM was conducted by suprapubic 2D ultrasound. Instructional videos with verbal cues guided the participants in when and how to perform the different exercises. IAP and PFM response were measured using femfit®, an intravaginal sensor capable of measuring a pressure profile at 8 locations along the length of the vagina. After each exercise the participants were asked if they perceived any discomfort, displacement of the sensor, whether they could maintain the pre-contraction, PFM fatigue and symptoms of PFD during the exercises. Wilcoxon signed rank test was used to analyse change in IAP and PFM response during the exercises, and to estimate change in differences between IAP and PFM with and without pre-contraction of the PFM.

Eleven women, mean age 25.6 years (SD±4.3), mean BMI 24.6 (SD±1.6), median strength training/week 1-3 times and mean 70 min/session participated. None of the participants had symptoms of PFD during strength training. There were no reports of displacement or discomfort from the femfit®. 
In most exercises, both PFM responses and IAP with pre-contraction were significantly higher than without pre-contraction (Figure 1). However, none of the pairs showed a large enough difference to be statistically significant (Table 1).

The PFM response with pre-contraction during squat, deadlift, leg press and curl up did not significantly exceed the increase in IAP.
The participants had never strength-trained their PFM and were instructed on how to perform a PFM contraction shortly before the experiment. Additional strength training of the PFM and practice of pre-contracting  during strength exercises, may be required for the pre-contraction to be effective. Pre-contraction may also influence other important factors in prevention of UI such as narrowing the levator hiatus and reducing downward movement of the pelvic floor which was not investigated in the present study (3).

The pressure response from the PFM was not statistically significantly higher than the IAP during squat, deadlift, leg press or curl up. Further studies are warranted to investigate if systematic strength training of the PFM can improve strength of the pre-contraction  during strenuous exercises.

Skaug, K. L., Engh, M. E., Frawley, H., & Bø, K. (2022). Prevalence of Pelvic Floor Dysfunction, Bother, and Risk Factors and Knowledge of the Pelvic Floor Muscles in Norwegian Male and Female Powerlifters and Olympic  Weightlifters. Journal of Strength and Conditioning Research, 36(10), 2800–2807. https://doi.org/10.1519/JSC.0000000000003919
Bø, K., & Nygaard, I. E. (2020). Is Physical Activity Good or Bad for the Female Pelvic Floor? A Narrative Review. Sports Medicine (Auckland, N.Z.), 50(3), 471–484. https://doi.org/10.1007/s40279-019-01243-1
Bø, K. (2024). Mechanisms for pelvic floor muscle training: Morphological changes and associations between changes in pelvic floor muscle variables and symptoms of female stress urinary incontinence and pelvic organ prolapse-A narrative review. Neurourology and Urodynamics, 43(8), 1977–1996. https://doi.org/10.1002/nau.25551