Trampoline-Induced Changes in Pelvic Structure and Continence

Urinary incontinence (UI) has traditionally been associated with postpartum or older women; however, growing evidence highlights its prevalence among young, physically active females - even in those without a history of pelvic floor dysfunction or childbirth. High-impact physical activities such as running, jumping, and trampolining have been shown to increase intra-abdominal pressure, placing acute mechanical stress on the pelvic floor and potentially contributing to urinary leakage. While the relationship between high-impact exercise and stress urinary incontinence (SUI) has been explored in terms of prevalence, less is known about the acute, real-time mechanical effects of impact loading on pelvic floor structures in asymptomatic individuals.

This study aims to investigate whether a 10-minute high-intensity trampoline protocol induces measurable changes in pelvic morphology - specifically in bladder neck position, levator plate length, and/or posterior urethrovesical angle (PUVA) - in physically active females aged 18-40 who do not report urinary incontinence symptoms. These anatomical parameters are indicators of pelvic floor support and dysfunction, and their change under load may signal early mechanical strain on the pelvic floor.

Participants will undergo a single study session involving a baseline transperineal ultrasound assessment, a 10-minute jumping bout, and follow-up ultrasound assessments immediately, and 30 minutes post-exercise. Urinary leakage is monitored during jumping via verbal self-report every 2 minutes, with descriptive classifications such as "drops," "squirt," or "gush." Jumping intensity is tracked using the Borg RPE scale and heart rate monitoring via Apple Watch, which has demonstrated acceptable validity for exercise heart rate tracking.

A repeated-measures design will be used to assess within-subject changes in pelvic morphology, with participants serving as their own control across time points. Data will be analyzed using repeated-measures ANOVA to determine statistically significant changes, with Cohen's d effect sizes calculated to assess magnitude of effect. Leakage data will be reported descriptively.

Ultimately, this study will generate foundational data on the immediate biomechanical response of the pelvic floor to high-impact activity. These findings may help identify early indicators of pelvic floor strain, even in women without symptomatic UI, and could inform future screening and prevention strategies for active female populations.

Inclusion criteria

• Aged 18-40
• Engage in regular physical activity or sport
• Do not experience frequent urinary leakage (no more than once per month during exercise, coughing, or sneezing)
• Can complete a 10-minute jumping protocol

Exclusion criteria

• Currently pregnant or have been pregnant in the past 6 months
• Have cardiac, pulmonary, metabolic, and/or neurological conditions
• Have a lower body injury that limits your ability to jump
• Have had a hysterectomy and/or incontinence surgery