Intra-abdominal pressure (IAP) is a key term used in discussions of pelvic floor loading and unloading during physical activity (PA) and has been implicated in urinary incontinence and pelvic organ prolapse [1]. It is debated whether excessive and/or prolonged increases in IAP may strain the female pelvic floor, or whether functional loading through IAP may instead provide a training stimulus. Further, IAP regulation is considered essential in pelvic floor rehabilitation and post-surgical care [2]. Despite widespread use of the term IAP, no consensus exists on how IAP should be measured or interpreted during PA. We aimed to understand how IAP is measured, inferred, and interpreted during PA and exercise, summarising sensor types, placement locations, activity contexts, reported values, measurement properties, and methodological limitations.

A scoping review methodology was selected to capture the broad range of research in which IAP has been measured during PA. The protocol was registered a priori on the Open Science Framework. Structured searches in Medline, Embase, and Web of Science databases were conducted (final update: January 30, 2025) to capture all peer-reviewed full-text studies reporting IAP as an outcome during PA or exercise. Studies were excluded if they involved non-human or pediatric populations, critically ill participants, did not report IAP as an outcome, or lacked original data. Title and abstract screening and full text reviews were conducted independently and in duplicate, with decisions based on consensus. Data extraction included sensor type and placement, participant characteristics, PA context, reported IAP values, calibration procedures, and measurement properties. Findings were synthesised following scoping review methodology [3].

Screening of 4,026 retrieved articles yielded 52 studies meeting the inclusion criteria. Several sensor types were identified: micro-tip catheters, ingestible capsules, piezoelectric sensors, air-filled balloon catheters, fluid-filled balloon catheters, and a suction-based device. Sensor locations spanned five body cavities (stomach, oesophagus, rectum, vagina, and bladder) and one placed externally the abdominal wall. Most studies included small samples (12 studies with 10 or fewer participants); 26 included only females and 13 included only males. Methodological differences in calibration, sampling frequency, and signal processing made cross-study comparisons difficult. Most sensors lacked validation for use during PA. Where validation existed, it was typically against another indirect IAP measure rather than a reference standard (Table 1). Sensor output had high variance, with lifting and jumping producing particularly high variability (coefficients of variation between 35 and 53%). Sensor outcomes for similar PAs varied by placement location: intragastric and intrarectal sensors showed the greatest variability, while intravaginal piezoelectric sensors were slightly more consistent, though migration occurred in up to 20% of cases. The forces contributing to sensor output and the inherent problems of motion artifact and under- or overdamping on signal fidelity were rarely discussed.

Intracavitary sensor output during PA represents a composite mechanical signal, summing IAP, organ weight, and acceleration load (Figure 1). Similar PAs can yield markedly different values depending on sensor type, placement, calibration and signal processing, rendering cross-study and cross-context comparisons invalid. This has direct clinical relevance: clinicians advising individuals with pelvic floor dysfunction or discussing pelvic floor loading and unloading in PA and exercise should recognise that sensor outcomes, referred to as “IAP” are highly influenced by other forces and are highly context-dependent. Standardised terminology and reporting, specifying sensor type, placement, calibration, and PA context, are needed before meaningful clinical thresholds can be established.

What is labelled as IAP in the literature involving PA is a composite of the mechanical loads acting on the sensor and motion artifact. Clinicians should interpret the literature and output from commercial devices with this in mind. Standardised reporting is needed to enable meaningful synthesis and evidence-based clinical decision-making.

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