Urinary incontinence (UI) during high-impact physical activity is highly prevalent among females, including nulliparae [1]. UI is particularly prevalent among trampolinists (80%)[2], where acceleration loading of the pelvic floor can reach 7 times the acceleration due to gravity [3]. It remains unclear whether UI experienced by high impact athletes during their sport activities arises from tissue strain related to cumulative exposure of the pelvic floor to high loads, or whether an acute bout of high impact loading may induce UI among active females who have never leaked urine. The aim of this study was to determine whether a standardized 10-minute mini-trampoline protocol induces UI among physically active, nulliparous, continent females who report never having experienced UI during daily physical activities.

This cross-sectional interventional study received approval from the local institutional research ethics board and included physically active, nulliparous females aged 18–40 years who self-reported never having experienced UI at baseline. Participants provided written informed consent prior to engaging in any study activities. With their bladder volume standardized to between 100 and 200mL, measured using 3D transabdominal ultrasound, participants performed a 10-minute mini-trampoline protocol designed to impose a single bout of repetitive high-impact loading. Participants were instructed to jump at the highest intensity they felt they could sustain for 10 minutes. UI and urge to void were self-reported at 2-minute intervals throughout the protocol. Bladder volume was measured immediately after the protocol. Descriptive statistics were used to summarize outcomes.

Twenty-seven participants (mean age 24.4 years, standard deviation (SD)= 2.3; mean body mass index 23.5 kg/m², SD= 3.2), all nulliparous, were included. Participants were highly active, engaging in sports including weightlifting, running, cycling, and various forms of strength and group exercise training, on average 6.7 (SD= 3.8) times per week. At baseline, all participants reported never having been incontinent. Over the course of the 10-minute protocol, exercise intensity increased from a mean Borg rating of perceived exertion (RPE; 6–20 scale) of 8.7 (SD= 1.5) at the start of the protocol to 12.7 (SD= 2.6) at 10 minutes, despite no increase in jumping frequency or intensity. Mean pre-exercise bladder volume was 142 mL (SD= 36.1), which increased by a mean of 83 mL (SD= 86.6) after the protocol. Urinary incontinence was first reported between the 4 to 6 minute interval and increased thereafter (Figure 1). Overall, 6/27 participants (22.2%, 95% CI 10.4%–40.1%) reported UI and an additional 2/27 (7.4%, 95% CI 2.1–23.4%) reported possible UI. An urge to void was reported by 6 of the 8 participants with UI or possible UI, as well as by 3 additional participants without UI. Four participants reported an urge to void at multiple timepoints, suggesting a sustained rather than episodic sensation, whereas UI was only reported as single events, described as small drops in five participants and a gush in one participant.

A standardized short-duration high-impact protocol provoked UI and an urge to void in a subset of young, physically active, nulliparous, continent females. These findings suggest that UI can occur in response to a single bout of high-impact loading and may not require cumulative exposure over time. The co-occurrence of an urge to void and UI indicates that both sensory input and activity-related mechanical loading may contribute to symptom provocation among high-impact athletes.

A single bout of high-impact activity may induce UI and urinary urgency in more than one in five females who are otherwise continent during physical activities. We need to further evaluate how pelvic floor and urethral function influence these symptoms.

Pires T, Pires P, Moreira H, Viana R. Prevalence of urinary incontinence in high-impact sport athletes: a systematic review and meta-analysis. J Hum Kinet. 2020;73(1):279–88. doi:10.2478/hukin-2020-0008.
Eliasson K, Larsson T, Mattsson E. Prevalence of stress incontinence in nulliparous elite trampolinists. Scand J Med Sci Sports. 2002;12(1):106–10.
Pendrill AM, Eager D. Free fall and harmonic oscillations: analyzing trampoline jumps. Phys Educ. 2015;50:64–70. doi:10.1088/0031-9120/50/1/64.