Exploring the connection between the hip and pelvic floor in women with exercise-induced urinary incontinence: integrating clinical hypotheses with current evidence

Abstract

Symptoms resulting from pelvic floor dysfunction, specifically urinary incontinence (UI), are more prevalent in female athletes than in those who do not exercise. However, female athletes do not often demonstrate the well-accepted impairments commonly associated with UI, such as pelvic floor weakness or atrophy. Additionally, factors such as greater exposure to impact, hormonal fluctuations caused by low energy availability and age-associated changes across the lifespan may negatively affect the passive tissues of the pelvic floor that are necessary to maintain continence. While high-level evidence supports the use of pelvic floor muscle training in the treatment of UI in the general population, there is mixed evidence for its use in the athletic population. To meet the needs of athletes, clinicians have adopted a more regionally interdependent model of care for UI, which relies heavily on hypothesized anatomical and functional synergies of the pelvic floor and the hip. This commentary aims to reconcile existing disparities between current clinical practice trends and available research in this area.

Introduction

Pelvic floor dysfunction (PFD), while once thought to be exclusively related to childbirth and ageing in people assigned female at birth, is widely experienced by the young, nulliparous athletic population (Joseph et al. 2021). Urinary incontinence (UI), the most frequent symptom of PFD, occurs in the general population at rates ranging from 22% to 80%, depending on the definition (Alves et al. 2017; Almousa & Bandín van Loon 2018, 2019; Bø & Nygaard 2020; Gram & Bø 2020; Skaug et al. 2022). Women who exercise have a three times greater risk of experiencing UI than those who do not (Alves et al. 2017; Almousa & Bandín van Loon 2018, 2019; Bø & Nygaard 2020; Gram & Bø 2020; Skaug et al. 2022). A quarter of all female athletes experience UI, with higher rates reported in impact sports such as gymnastics, and track and field (Bø 2004a; O’Halloran et al. 2012; Alves et al. 2017; Dakic et al. 2021, 2022). These estimates are conservative because symptoms are often underreported and undertreated in this population (Reymert & Hunskaar 1994; Hägglund & Wadensten 2007; Howard & Steggall 2010).

Stress UI (SUI), i.e. the complaint of involuntary loss of urine with physical exertion (e.g. sporting activities), or sneezing or coughing (Haylen et al. 2010), was previously presumed to result from weakened or potentially injured pelvic floor muscles (PFMs), tissue laxity, and/or a wider urogenital hiatus (Bø 2004b; Ashton-Miller & DeLancey 2007). Interestingly, studies have shown that female athletes have stronger PFMs with a greater cross-sectional area than non-athletes, but they also demonstrate a higher prevalence of SUI than their non-athlete nulliparous counterparts (Kruger et al. 2005, 2007; Araujo et al. 2015; Bø & Nygaard 2020). This highlights a gap in our understanding of the impairments leading to UI in athletes. The term exercise-induced UI (EIUI) has been used to describe incontinence in this population. The occurrence of UI under a greater load or physical fatigue while performing exercise distinguishes EIUI from SUI (Petter Rodrigues et al. 2024).

The aetiology of UI and mechanisms by which PFM training (PFMT) addresses UI are robust fields of research (Sheng et al. 2022; Bø 2024c). While less is understood about EIUI, SUI is multifactorial. The latter can include impairments related to passive physiological components such as the reflexive tissue stiffness necessary to support the bladder and urethra (Falah-Hassani et al. 2021; Pipitone et al. 2021), and active components, such as neuromuscular control, and the strength and power of the PFMs, bladder neck and urethral sphincter. These factors cumulatively affect urethral closure pressure, and therefore, continence (Rud 1980; Trowbridge et al. 2007; Falah-Hassani et al. 2021). Additionally, external demands placed on the body, or physiological factors across the lifespan, such as hormonal fluctuations, activities of daily living, parity and sport, will play a role in the function of both passive and active components (DeLancey et al. 2008a). Although urethral failure is recognized as the primary cause of SUI (DeLancey et al. 2008b), the contribution of many impairments resulting in EIUI makes using an impairment-based intervention challenging. Differences in urethral morphology associated with urethral failure are often unable to be modified with PFMT, and may be congenital (urethral length) or acquired across the lifespan (bladder neck funnelling). However, other muscular and passive tissue impairments associated with incontinence can be modified via PFMT, including thickness of the levator ani and external urethral sphincter muscles, hiatal dimension, and passive stiffness of the PFMs (Falah-Hassani et al. 2021; Pipitone et al. 2021). For a more in-depth review of the pathophysiology of UI see Falah-Hassani et al. (2021) and Pipitone et al. (2021).

Although impairments of multiple non-muscular structures are thought to contribute to UI, evidence continues to emerge about the effectiveness of individual responses to PFMT (Bø 2003; Bø et al. 2024). Pelvic floor muscle training is the conscious contraction and relaxation of the PFMs (Sheng et al. 2022). There is high-quality evidence (grade A, level 1) for the use of PFMT to reduce SUI in the general population (Dumoulin & Hay-Smith 2008; Hay-Smith et al. 2024), and inconclusive (Petter Rodrigues et al. 2024) to favourable (Rodríguez-Longobardo et al. 2024; Skaug et al. 2024) evidence in athletic populations. The addition of strength training to PFMT has been shown to reduce UI symptoms in an older population, an intervention thought to address age-related sarcopenia (Virtuoso et al. 2019; McCloskey et al. 2024). However, clinicians working with athletic populations question whether the translational effects of isolated PFM strengthening and hypertrophy with or without general strength training meet the demands of this group because of the sport-specific needs of cutting, twisting, deceleration, repetitive impact and full-body power production.

The rapid evolution in our understanding of the multiple impairments underlying SUI and its treatment has resulted in confusion for clinicians seeking evidence-based guidance to treat this population. As a result, many clinicians apply the general principles of anatomy, biomechanics and tissue adaptations to develop impairment-based management approaches for female athletes with EIUI. These methods, including integrating lower extremity inter-regional strategies, have focused on hip rotation and the role of the obturator internus (OI) as an indirect way to affect incontinence.

Manual therapy to the hip joint, hip rotation range of motion (ROM) and strengthening, and sport-specific motor control interventions targeting hip rotational control are regionally interdependent interventions that are often used in an attempt to manage impairments that are hypothesized to affect the pelvic floor’s function in continence or the hip’s role in force transmission during exercise. These hip-focused interventions build on an assumed functional and anatomical relationship between the hip and pelvic floor via the OI and its fascial attachment, the arcus tendineus levator ani (ATLA) (Occelli et al. 2001; Pit et al. 2003; Ashton-Miller & DeLancey 2007; Prather et al. 2009; Yoo et al. 2015; Tuttle et al. 2016; Amorim et al. 2017). However, what evidence exists to support the anatomical and functional interaction of the hip and pelvic floor? Additionally, what does the evidence show regarding the effects of hip interventions on EIUI?

In the present commentary, the authors aim to reconcile differences between current clinical practices based on hypothetical anatomical interactions between the hip and pelvic floor, and the available evidence. While they use the terms “women” and “female”, the discussion of anatomy, examination and intervention are relevant for individuals assigned female at birth who may have a different gender identity. Furthermore, the present authors explore how existing evidence of the pelvic floor’s role in UI and the hip’s role in force transmission during activity may be used in tandem to mitigate the symptoms of EIUI in athletes.

Anatomical and functional role of the pelvic floor in urinary incontinence

Multiple muscular, fascial and ligamentous structures make up and are treated collectively as “the pelvic floor” (Eickmeyer 2017; Ashton-Miller et al. 2001). The levator ani is composed of three distinct muscles: the pubococcygeus (or pubovisceral), puborectalis and iliococcygeus. The pubovisceral and puborectalis muscles originate from the inner surface of the bony pelvis (Fig. 1). The dense connective tissue of the ATLA serves as the origin for the iliococcygeus. The urogenital diaphragm is made up of a fascial layer, the perineal membrane, the compressor urethra, the sphincter urethra and the urethrovaginalis. Most superficially, the bulbospongiosus, ischiocavernosus, superficial transverse perineum and perineal complex support the urogenital hiatus (DeLancey et al. 2024c), and have a sphincter-like action on the distal vagina. For a more in-depth review of pelvic floor anatomy, please see Ashton-Miller & DeLancey (2007) and Herschorn (2004).

Figure 1.

Clinically hypothesized model of the effect of hip position on the muscular state of the pelvic floor: (a) hip in neutral rotation, the obturator internus (OI) and levator ani produce directionally opposite forces on the arcus tendineus levator ani; (b) hip in external rotation, the OI and levator ani are shortened; and (c) hip in internal rotation, the OI and levator ani are lengthened.

Continence is affected by two functional systems: support and sphincteric closure (Ashton-Miller et al. 2001). The pelvic diaphragm supports the pelvic organs and tissues against excessive caudal pressure from increased intra-abdominal pressure. This support function relies on the anatomical configuration of the levator ani with the endopelvic fascia, adequate cross-sectional area or muscle bulk, and both the active and passive components of muscle tone (Worman et al. 2023). Resting tone helps to maintain urogenital hiatal closure (Ashton-Miller et al. 2001; Ashton-Miller & DeLancey 2007). The anterior vagina, endopelvic fascia and arcus tendineus fasciae pelvis provide additional support (Ashton-Miller et al. 2001; Ashton-Miller & DeLancey 2007).

Sphincteric function aids continence when intra-abdominal pressure rises by increasing urethral closure pressure above bladder pressure (Enhorning 1961). This system is reliant on the muscular force of both the striated muscles of the external urethral sphincter (EUS), and the longitudinal smooth muscle of the internal urethral sphincter, adequate blood flow from the vascular plexus, intact passive tissue and muscle tone of the levator ani to provide a stiff backdrop for urethral compression (Quinn & Domoney 2009; Falah-Hassani et al. 2021; Pipitone et al. 2021). Urethral failure, or insufficient urethral closure pressure, is the predominant cause of SUI (Pipitone et al. 2021). Maximal urethral closure pressure is 40% lower in women with SUI versus women without it (DeLancey et al. 2008b). Changes related to ageing, such as sarcopenia and decreased oestrogen, have been shown to decrease the muscle thickness of the EUS, affect the strength of supportive structures around the urethra and decrease periurethral vascularity, which all affect continence (Quinn & Domoney 2009; Falah-Hassani et al. 2021). However, beyond the known decline in maximal urethral closure pressure of 15 cmH₂O per decade for nulliparous women, changes to urethral closure pressure in young nulliparous athletes have not been studied in depth (Trowbridge et al. 2007). Potential pathophysiological hypotheses for decreased closure pressure unique to young nulliparous athletes may be related to: low oestrogen levels resulting from decreased energy availability and functional hypothalamic amenorrhea (Rebullido & Stracciolini 2019); or insufficient muscular endurance of the EUS as a result of low energy availability since the this sphincter primarily consists of type I muscle fibres (Rebullido & Stracciolini 2019; McCloskey et al. 2024).

Both the sphincteric closure and muscular support systems must contract in anticipation of and in reaction to changes in intra-abdominal pressure to maintain continence (Ashton-Miller & DeLancey 2007; Hodges et al. 2007; Morin et al. 2017; Leitner et al. 2019). Stiffness and the resting length of both groups of muscles may affect these properties of coordination and adaptability (Hodges et al. 2007; Morin et al. 2017; Leitner et al. 2019). The internal urethral sphincter is responsible for resting urethral closure pressure, while the EUS is responsible for increased urethral pressure during periods of elevated abdominal pressure (McCloskey et al. 2024). During coughing or sneezing, the pelvic floor (i.e. the levator ani and superficial muscles) and abdominals contract synergistically in anticipation of increased pressure to support the continence closure mechanism and guide pressure superiorly, reducing strain on the visceral tissue (Hodges et al. 2007; Cavallari et al. 2017; Talasz et al. 2022). During landing impact, the pelvic floor reacts to increased downward pressure by eccentrically lengthening to control organ descent (Ashton-Miller et al. 2001; Dias et al. 2017). For repetitive tasks, such as running, PFMs demonstrate tonic activity with anticipatory and reactive phasic bursts (Hodges et al. 2007). This ability of the PFMs to automatically coordinate appropriate activation, timing and sequencing when undergoing increases in pressure during impact activities falls outside of the strength and ROM impairments targeted with PFMT (Sjödahl et al. 2016; Moser et al. 2018).

Current evidence for pelvic floor muscle training

Evidence is currently mixed regarding the proposed mechanism of PFMT and how it reduces SUI (Theofrastous et al. 2002; Bø 2003; Sheng et al. 2022). A systematic review and meta-analysis reported that PFMT produced both a significant increase in maximal voluntary contraction of the PFMs, and a substantial reduction in the amount of urinary leakage in female athletes (Rodríguez-Longobardo et al. 2024). Conversely, a prior scoping review revealed only weak to no evidence of PFMT improving UI as a result of improved levator ani muscle strength, but some for improved continence because of improved awareness of the PFMs (Sheng et al. 2022). Pelvic floor muscle training has been shown to affect pelvic floor morphology in the following ways: improved bladder neck position; narrower hiatal dimensions; thicker external urethral sphincters (Madill et al. 2015); and an increase in the cross-sectional area of the PFMs (Bø 2024c). However, not all studies show an association between morphological changes and incontinence status (Bø 2024c).

While the intention of PFMT is to improve the support and sphincteric function of the PFMs to counteract downward pressure on the pelvic viscera and urethra, another variable in maintaining continence is the magnitude and speed of the force being imparted on these structures. The role of the levator ani in transmitting and attenuating force from the lower extremity, and its effects on continence are unknown. This could be a missing contributor to EIUI because of the potential strain on pelvic structures imparted by accelerating and decelerating the body on top of a lower extremity via the pelvis. Although the synergistic relationship of the pelvic floor and abdominal muscles in modulating intra-abdominal pressure have been studied, the synergistic role of the pelvic floor and the deep hip musculature in attenuating force from the lower extremity has not.

Anatomical and functional role of the hip in force transmission

As a ball-and-socket joint, the hip requires precise control in all three planes of motion. While control of motion in the sagittal and frontal planes is often implicated in hip and knee injury, the focus here is on the transverse plane, given the anatomical proximity and hypothesized functional synergy between the hip and pelvic floor (Occelli et al. 2001; Pit et al. 2003; Ashton-Miller & DeLancey 2007; Prather et al. 2009; Yoo et al. 2015; Tuttle et al. 2016; Amorim et al. 2017). Transverse plane hip rotation can be achieved by the pelvis rotating on a stationary femur (foot on the ground/loaded), the femur rotating under a stationary pelvis (unloaded) or a combination of the two. Sport performance requires both femur-on-pelvis and pelvis-on-femur movement of the hip joint. The rotational motion available at the hip depends on its position, and bony and soft tissue. In hip flexion, rotation may be limited by bony morphology, such as the cam or pincer morphology associated with femoroacetabular impingement syndrome (Wyss et al. 2007; Griffin et al. 2016). In a neutral hip position, rotation may be limited by the hip ligaments, which are stretched more in extension than mid-flexion (Martin et al. 2008; van Arkel et al. 2015). In either position, pain can also limit motion (Tak et al. 2016; Silva et al. 2020).

In “neutral” rotation, the position of the femoral head relative to the acetabulum affects the available rotational motion. Femoral torsion, sometimes called femoral version, is a medial rotation or twist of the femur represented by the angle between the femoral neck and shaft (Wells et al. 2017; Scorcelletti et al. 2020). The average amount of torsion in skeletally mature individuals varies significantly based on sex, ethnicity and race (Koerner et al. 2013). Torsion is consistently higher in females than males (Koerner et al. 2013). Angles beyond 25° are considered femoral anteversion, while angles below 8° are considered retroversion (Fabry et al. 1973; Murphy et al. 1995; Clohisy et al. 2009; Akiyama et al. 2012; Koerner et al. 2013; Nakahara et al. 2014; Jiang et al. 2015; Chadayammuri et al. 2016; Wells et al. 2017; Litrenta & Domb 2018; Sankar et al. 2018; Akinmokun et al. 2020). As the degree of femoral torsion increases, the hip appears internally rotated when the femoral head is neutrally aligned within the acetabulum. The acetabulum, or socket component of the hip, is oriented approximately 20–40° anteriorly and 30–40° inferiorly, allowing large ranges of hip flexion and abduction. Analogous to femoral torsion, as acetabular anteversion increases, the hip appears internally rotated. Increased femoral torsion and/or acetabular anteversion results in increased internal rotation, and decreased external rotation available motion (Akiyama et al. 2012; Nakahara et al. 2014; Chadayammuri et al. 2016; Sankar et al. 2018). Similarly, as femoral torsion or acetabular anteversion decreases, potentially becoming retroverted, the hip appears externally rotated when the femoral head is aligned.

Acetabular structural differences can also result in increased or decreased hip rotational ROM. The degree of acetabular coverage over the femoral head is quantified by the lateral centre edge angle (LCEA). An LCEA < 20° is typically classified as acetabular dysplasia, which is a multiplanar structural deformity with a shallow acetabulum or socket (Wiberg 1939; Wilkin et al. 2017; Wyatt & Beck 2018; Reiman et al. 2020; Schmitz et al. 2020). Females with hip dysplasia present with highly variable movement patterns when performing common tasks such as squatting compared to asymptomatic female controls, potentially requiring greater neuromuscular control of loaded, pelvis-on-femur athletic movements. An LCEA ≥ 40° indicates pincer morphology, resulting in decreased hip internal rotation ROM, and is a potential contributor to femoroacetabular impingement syndrome (Tannast et al. 2007; Clohisy et al. 2011). Analogous to increased femoral torsion, both acetabular dysplasia and pincer morphology are more prevalent in females (Nakahara et al. 2014; Kapron et al. 2015; Gala et al. 2016; Raveendran et al. 2018; Schmitz et al. 2020; LaPrade et al. 2021). Thus, before interventions are made that will affect hip ROM, strength and control, the anatomical structure of the femur and acetabulum must be considered. Appreciating the range of anatomical variability of these structures during clinical examinations of female athletes allows for a better understanding of structural effects on the available motion, muscle length–tension relationship and neuromuscular control requirements in athletic movements of the lower extremities.

Muscular control of movement through available hip rotation is essential for function and athletic performance. Since hip position changes from extension to flexion, many hip muscles switch from producing external rotation to generating internal rotation as their line of action moves from behind the hip axis to in front of it (Delp et al. 1999). Thus, the ability to control internal rotation (or to produce external rotation), whether from the femur rotating under the pelvis or the pelvis rotating on the femur, is reduced as the hip is flexed through either anterior pelvic tilt or femoral flexion. The deep hip rotators (i.e. the piriformis, gemellus inferior and superior, OI and externus, and quadratus femoris muscles), which maintain an external rotation moment arm even in hip flexion, also serve a pivotal role in joint stability (Retchford et al. 2013). These muscles, which have short fibre and sarcomere lengths, small physiological cross-sectional areas, and low pennation angles, help to maintain the femoral head within the acetabulum (Parvaresh et al. 2019; Meinders et al. 2022). The primary role of the deep hip external rotators is to provide hip stability and control transverse plane motion of a loaded lower limb (Parvaresh et al. 2019; Meinders et al. 2022). Coordination of the deep hip external rotators is not only desired to decrease lower extremity injury, but also to optimize performance.

Control of hip rotation and stability is particularly important during single-limb activities in sport. With both feet on the ground, the motion of the pelvis is constrained by both hips. In loaded single-limb activities, the stance hip must control not only the femur and pelvis in response to high-impact forces, but also the mass of the head, arms, trunk and non-stance leg. Adequate ROM and eccentric control of hip internal rotation during landing is necessary to reduce lower extremity stiffness (Goodwin et al. 2019), and excessive strain on static tissues. (Zhang et al. 2000). Increased lower extremity stiffness results in reduced joint excursion and greater loading through bone and cartilage, while excessive or uncontrolled joint excursion is a sign of inadequate eccentric muscle action and decreased force mitigation; either extreme results in lower extremity injury (Zhang et al. 2000; Goodwin et al. 2019; Sever et al. 2024). This dynamic stability of high-velocity lumbopelvic rotation with one limb planted on the ground is a primary function of the deep hip rotators, assisted by the gluteal muscles (Neumann 2010).

Clinically hypothesized functional relationship of the hip and pelvic floor

The integration of deep hip rotator interventions into rehabilitation for PFD is based on the assumption that the levator ani and OI act similarly to other synergistic muscles attaching to a common tendinous insertion. It is also commonly thought that the OI and the levator ani share an attachment via a thickened band of fascia, the ATLA. Therefore, a change to one muscle may affect the function of the other (Occelli et al. 2001; Pit et al. 2003; Ashton-Miller & DeLancey 2007; Prather et al. 2009; Yoo et al. 2015; Tuttle et al. 2016; Amorim et al. 2017). Through this interaction, some clinicians infer that habitual postures or exercise of the hip will affect the resting length, tissue stiffness, operating range and force-generating capacity of the PFMs. Table 1 describes the clinically hypothesized biomechanical scenarios affecting the muscular state of the pelvic floor, including hip position and movement.

Table 1.

Hypothesized pelvic floor length and neuromuscular activity based on movement and function

Levator ani muscle	Pelvic floor and hip function scenarios
Actively shortened	Voluntary concentric pelvic floor contraction (Kegel exercise)
	Involuntary (anticipatory and reactive) pelvic floor contraction in response to changes in intra-abdominal pressure for effective cough/sneeze
	Active hip external rotation*
Passively shortened	Approximation of bony pelvis (sacroiliac joint belt) Passive hip external rotation*
Actively lengthened	Eccentric contraction
	Deceleration of pelvis on top of femur into internal rotation of the loaded limb*
	Muscular response to increased intra-abdominal pressure as a result of impact
	Synergistic movement with diaphragmatic inhalation
Passively lengthened	Passive hip internal rotation*
	Active hip internal rotation of an unloaded limb*

^*These principles are hypothesized by clinicians, and have not been scientifically investigated for the levator ani muscle.

Hypotheses for the muscular actions of both the OI and levator ani are made on the basis of the assumptions above. These include the muscles theoretically pulling in opposing directions when concentrically active (Fig. 1a), or lengthening and shortening in the same direction when acting synergistically (Fig. 1b and 1c). An anticipatory contraction of the levator ani stabilizes the ATLA, allowing the OI to generate force for concentric shortening or eccentric lengthening without unintended effects on the pelvic floor. If the OI is quickly and eccentrically loaded during impact, either appropriately to mitigate force to the lower extremity or inadequately, resulting in excessive motion of the lower extremity, and is unopposed by an anticipatory levator ani contraction, this could result in a quick stretch of the levator ani and potentially change muscle tone over time (Fig. 1c).

The influence of repetitive eccentric loading of the OI on the obturator fascia (OF), theoretically causing increased stiffness over time (Wilke et al. 2022), is also one of two hypothesized mechanisms by which neuromuscular control of the pelvis on the femur affects continence. Increasing the passive stiffness of the fascia that provides support to the pelvic diaphragm and bladder neck (Herschorn 2004) could address impairments (e.g. bladder neck position and levator hiatal width) that are affected by repetitive impact, and are associated with incontinence. Additionally, structural shortening of the posterior pelvic floor resulting from prolonged positioning or focused strengthening into hip external rotation would decrease the available ROM of the levator ani, and theoretically, the hip (Fig. 1b).

Therefore, impaired hip ROM and strength are thought to affect the functional capabilities of the levator ani, including the muscles’ coordination, timing and ability to adapt to changes in pressure. Reduced hip internal rotation ROM may lead to adaptive shortening of the levator ani, impeding its ability to eccentrically lengthen and accommodate caudally directed forces. This would result in more force on the pelvic viscera and urogenital hiatus. Alternatively, increased (excessive) hip internal rotation ROM would result in a less-effective pelvic floor contraction, potentially because of an inability to create sufficient force in the resting lengthened position (Hartigan et al. 2019) (Fig. 1c). The inability of the levator ani to both decelerate superincumbent forces (because of greater resting tone), and create sufficient force (because of greater length) could lead to PFD. Therefore, it is hypothesized by some clinicians that impairments of resting length and tone, force generation capacity, and neuromuscular control of the OI could affect the same variables in the levator ani.

Current evidence for the connection between the hip and the pelvic floor

The inference that the muscular properties of the OI will affect those of the levator ani, and therefore, continence relies on three assumptions: (1) the OI and levator ani muscles share a common attachment to the ATLA; (2) the ATLA acts as a tendon, similar to others in the body (e.g. the patellar tendon), in direct force transmission; and (3) the levator ani plays a primary role in maintaining continence. Existing evidence of each assumption is reviewed below.

The OI originates from the posterior surface of the obturator membrane (fascia), and the rami surrounding the obturator membrane, not the ATLA. The OF is part of the parietal fascia, and is attached superiorly to “the inferior border of the superior ramus of [the] pubic bone, posteriorly attached to the anterior border of the greater sciatic notch, inferiorly attached to the ischial spine and arcus tendinous fasciae pelvis [. . .], and anteriorly fused with the fascia of the puborectalis muscle” (Chin et al. 2021, p. 2). A histological study by Muro et al. (2023) demonstrated broad planar contact of both the OI and levator ani muscles along the OF (height of contact area = 24.6 ± 9.1 mm), with fibres of the levator ani extended beyond the ATLA to the superior ramus of the pubis, not the distinct attachment along a line of tissue traditionally seen in anatomical schematics. Muscles sharing laminal contact through a fascial plane opposes the clinical hypothesis of tissue connection in series with a tendon-like force transmission.

Additionally, research investigating the anatomical and mechanical interaction between the OI, levator ani and ATLA has yielded conflicting results. Evidence from cadaveric dissection demonstrates that the ATLA is an independently supported structure attached to the pubis and ischial spine, fusing with the OF, but not the obturator muscle, and serving as an attachment to the iliococcygeus (Kim et al. 2015; DeLancey 2024; DeLancey et al. 2024a). Removal of the OI does not affect the structural position of the levator ani (DeLancey 2024). While the evidence shows that the OI, OF and levator ani do not rely on one another for structural support, there is shared direct or indirect anatomical contact with the ATLA, and potential for indirect mechanical interaction. In an electromyographic study, electrophysiological stimulation of the OF above the ATLA triggered a contraction of the levator ani muscles at their insertion (Chin et al. 2021). Levator ani force production is affected by the integrity of the ATLA’s connection to the pubic bone. In the presence of a levator injury (avulsion), force production of the levator ani may be compensated for by lateral structures, including the OI (DeLancey et al. 2024b).

There are currently no published studies investigating lower extremity force transmission and attenuation through the OI and levator ani. However, there is evidence of fascia assisting in the absorption and distribution of mechanical force in other parts of the body (Wilke et al. 2018), bolstering the hypothesis that the OF may play a role in neuromuscular function of the pelvic floor in response to impact through the lower extremity. It may be helpful to consider the structural and functional relationship of the abdominal muscle layers surrounding the trunk as one such example. The five abdominal muscles are arranged in a laminar fashion with muscle fibres running in variable directions and intersecting fascial planes. Although the muscles have distinct support and functions, one side of the rectus abdominis does not rely on the other for structural support; for example, both sides cooperate in transmitting force around the trunk and maintaining intra-abdominal pressure (Varacallo et al. 2023).

Lastly, the utility of the anatomical and mechanical association of the OI with the pelvic floor in the management of EIUI relies on the role of the levator ani in the continence mechanism, which may be clinically overemphasized. The levator ani contributes to anticipatory and reactive pressure management, and pelvic organ support. Additionally, it serves as a backdrop for urethral compression. The levator ani’s resting tone, length, neuromuscular timing and force-generating capacity are thought to have an impact on pressure management, specifically the coordination needs of impact. However, the link between hip function and pressure management is currently unknown beyond the previously illustrated untested clinical hypothesis related to the anatomical connection, and subsequent muscular and fascial tissue adaptations. The role of the levator ani in the sphincteric mechanism of continence is minimal compared to that of the superficial PFMs and passive tissue supports of the urethra (Herschorn 2004; Pipitone et al. 2021). There are anatomical models depicting a connection from the bladder neck and proximal urethral support of the urethropelvic ligaments to the arcus tendineus of the pelvic fascia (Herschorn 2004). It is through the connection of the OI to the OF and the levator ani to the ATLA that both muscle groups may affect the support of the sphincteric system via the endopelvic fascia.

The mechanism by which the hip muscles affect pelvic floor function remains largely unknown. However, investigations concurrently examining hip function and the symptoms of PFD continue to reveal associations. Decreased hip external rotation and abduction strength are associated with SUI in older women, but not pelvic floor strength or endurance (Hartigan et al. 2019; Foster et al. 2021). Additionally, hip adduction and internal rotation angles in weight acceptance and midstance phases of gait were increased in women with SUI compared to women without SUI (Hartigan et al. 2020). This is consistent with the biomechanical work that associates decreased eccentric neuromuscular control of the hip under impact with the presence of lower extremity injury. A 12-week hip external rotation strengthening programme improved vaginal squeeze pressure and hip rotator strength in both a younger and an older population, and in those with and without PFD (Tuttle et al. 2016, 2020). The programme additionally improved Pelvic Floor Distress Inventory – Short Form 20 scores for those with PFD (Tuttle et al. 2020). Furthermore, strengthening hip muscles in addition to PFMT showed a favourable outcome, i.e. decreased frequency of urine leakage, despite no differences in PFM strength or perineometry when compared to PFMT alone (Marques et al. 2020).

The previously presented evidence supports the notion that improved hip muscle strength in isolation improves continence. However, the mechanism remains unclear, and the outcome measures used do not capture the higher demands of athletic activity. Observational studies have identified associations between hip control in weightbearing and the presence of SUI (Hartigan et al. 2020). Furthermore, hip strengthening improves one’s overall work capacity and muscle mass, and potentially reduces intra-abdominal pressure down on the sphincteric system, which is inevitable when working over 80% of a maximum voluntary contraction (MacDougall et al. 1992).

One aspect of continence that is not addressed in the biomechanical clinical hypothesis of the pelvic floor and hip connection is the proximity of the neural structures of continence to the OF (Falah-Hassani et al. 2021). The EUS is innervated by the deep perineal branch of the pudendal nerve (Sam et al. 2023). This nerve travels through Alcock’s canal, a thickening of the OF (Sam et al. 2023). An alternative hypothesis of hip muscle function affecting continence is that neuromuscular deficits along the path of the pudendal nerve as it innervates the EUS may be enhanced through improvements in hip ROM and function allowing for improved neural mobility (McCloskey et al. 2024).

Although current evidence suggests that hip muscle strengthening may play an adjunct role in the management of SUI (Cook et al. 2017; Kurz & Borello-France 2017) and EIUI in younger females, there is a lack of evidence to support the previously described clinically hypothesized relationship between the levator ani and the OI through the ATLA, as commonly depicted. The mechanism by which hip ROM, control and strength affect continence is as multifactorial as the impairments attributed to EIUI, and is currently hypothetical. Future research investigating the effects of hip strength, ROM and control in sport-specific tasks in athletes with and without EIUI that utilizes advanced imaging, dynamometry and electromyography of the pelvic floor is warranted in order to better understand the synergy of the hip and pelvic floor.

Current limitations in interventions addressing exercise-induced urinary incontinence

The prevailing opinion amongst clinicians working with female athletes with EIUI is that solely addressing isolated muscular weakness of the pelvic floor in non-weightbearing positions fails to prepare female athletes for the demands of impact, cutting, turning and producing power with optimal force transfer, but without the symptoms of PFD. Further investigation of a regionally interdependent, impairment-based approach to address EIUI is necessary. The limited availability of evidence at both the mechanistic and interventional levels of understanding EIUI makes a proposed paradigm purely theoretical. An impairment-based intervention model could include categorization of muscle performance, mobility, motor control and overload to guide interventions similar to that suggested by Willy et al. (2019) for patellofemoral pain (see Table 2). While a full exploration of sport-specific exercise progression is beyond the context of the present commentary, the authors hope that, by providing the current evidence for both the anatomy and function of the pelvic floor in urinary continence, and the OI in force attenuation and transmission in weightbearing activities, one can use the principles of tissue adaptation, strength, ROM, motor control and return to sport once impairments have been identified.

Table 2.

Theoretical impairment-based classification for management of pelvic floor dysfunction in female athletes

Impairment classification	Pelvic health examples
Muscle performance	Weakness or lack of endurance in the pelvic floor, and surrounding hip and core musculature
Mobility	Inability to lengthen the pelvic floor, and limited passive range of motion of the hip
Motor control	Inability to anticipate and react to changes in intra-abdominal pressure, or control lower extremity posture and dynamic movement with adequate strength and range of motion
Overload	Excessive intra-abdominal pressure with inappropriate pressure management strategies (e.g. breath-holding, bearing down, and lack of co-contraction of the pelvic floor and abdominal wall musculature)

Additionally, many of the impairments associated with urethral failure are not modifiable (Ashton-Miller et al. 2001; Ashton-Miller & DeLancey 2007) by conservative therapeutic intervention alone. Collaborating with a multidisciplinary team to carry out appropriate diagnostic testing, such as ultrasound, electromyography or magnetic resonance imaging to identify impairments, may be necessary since common clinical tests such as levator ani strength and endurance have mixed evidence for their role in continence (Falah-Hassani et al. 2021). Pelvic physiotherapists can additionally recommend the use of external support, such as a pessary, to aid in sufficient urethral closure. If urethral closure pressure cannot be effectively improved through an impairment-based therapeutic approach, or with support devices, alterations to the amount or duration of intra-abdominal pressure may be necessary through activity modification (i.e. type, load, volume and intensity) for women participating in impact exercise who wish to reduce EIUI (Petter Rodrigues et al. 2024).

Limitations of musculoskeletal physiotherapy management of exercise-induced urinary incontinence

The present authors acknowledge the limitations of a biomechanical approach to address the factors contributing to PFD in female athletes. A whole-systems approach, similar to that recommended by Donnelly et al. (2022) for returning to running postpartum, is recommended. When an athlete demonstrates a lack of improvement in symptoms and performance that is inconsistent with their musculoskeletal (MSK) prognosis, collaboration with other members of the multidisciplinary team (e.g. physicians, nutritionists and psychologists) may be indicated in order to assess additional organ systems. These appraisals could include cardiovascular status (vascular plexus), connective tissue health (generalized hypermobility), vulvo-urethral anatomy and function, endocrine and metabolic function (nutrition and energy availability) (Mountjoy et al. 2023), and psychosocial factors, including overtraining.

Conclusion

In summary, female athletes are more likely to experience UI in the absence of weakness or atrophy. They may have unique impairments related to differences in passive tissue support, neuromuscular timing and sequencing needed for impact and force attenuation, and further unknown impairments of the hip and lower extremity. The anatomical and functional synergy between the pelvic floor and deep hip rotators is nuanced, and lacks consensus in evidence. Hip strengthening may be used as a potential adjunct in the management of female athletes with incontinence. However, the mechanism of effect remains unknown, and there is a lack of studies that test its impact on higher-level athletic demands. Further high-quality research is needed to investigate the association between PFM function, morphology and passive tissue stiffness in relation to hip strength, ROM and control in athletic tasks similar to biomechanical studies assessing lower-extremity kinetics and kinematics. The use of an impairment-based, regionally interdependent model to address EIUI matches the paradigm for dysfunction in other body regions, and deserves to be further studied to better meet the needs of female athletes.

Biographies

Laurel Proulx PT DPT PhD is a clinical assistant professor in the Baylor University Doctor of Physical Therapy programme. She earned her bachelor’s degree in exercise science from the University of Kansas, Lawrence, KS, USA, in 2009, her doctorate of physical therapy from Regis University, Denver, CO, USA, in 2013 and her PhD from Texas Woman’s University, Denton, TX, USA, in 2021. Laurel is an American Board of Physical Therapy Specialties board-certified orthopaedic clinical specialist, and primarily treats the pelvic health population. Clinically, her passion is exploring the biomechanical link between the hip, lower extremity and core cannister to the pelvic floor, while also implementing pain science principles for those with complex pelvic pain presentations. Her research primarily focuses on the relationship between MSK function and PFD, and she has a vested interest in improving the efficacy and availability of treatments for individuals with pelvic pain. Laurel has written multiple peer-reviewed publications, and her work is supported by significant federal funding. She serves her community through her private clinical practice, and has been a consultant for Nike’s prenatal and postpartum programming within their Training Club app.

Jenny LaCross PT DPT PhD ATC CLT is an American Board of Physical Therapy Specialties board-certified clinical specialist in women’s health physical therapy with over a decade of experience in a variety of pelvic health settings across the USA. She received her Bachelor of Science degree in Kinesiology – Athletic Training from the University of Michigan, Ann Arbor, Michigan, USA, and her Doctorate of Physical Therapy from Washington University in Saint Louis, Saint Louis, MO, USA. Jenny’s passion for pelvic health care led her to complete a 15-month post-professional physical therapy residency in women’s and men’s health at the University of Pittsburgh Medical Center: Centers for Rehab Services, Pittsburgh, PA, USA, where she also became a certified lymphoedema therapist and clinical instructor. She then completed a post-professional certificate programme in women’s health physical therapy and her PhD in physical therapy at Texas Woman’s University in 2018 and 2023, respectively. Jenny values service to the profession, and has volunteered for the American Physical Therapy Association (APTA) Academy of Pelvic Health Physical Therapy in numerous roles, including chair of the clinical practice guideline on physical therapy management of constipation development team, vice-chair of the research committee, assistant chair of the educational review committee and item writer/member of the specialized academy of content experts in women’s health. She currently practises part-time at MOVE Physical Therapy in Monroe, MI, USA. In her full-time role, Jenny is a postdoctoral research fellow with University of Michigan’s Pelvic Floor Research Group, where she studies motor control of the pelvic floor, and associations between pelvic floor morphology and physical activity in ageing female populations under the mentorship of Dr John DeLancey MD, Dr James Ashton-Miller PH and Dr Janis Miller PhD APRN.

Cara L. Lewis PT PhD FAPTA is a professor in the Department of Physical Therapy within Boston University’s Sargent College of Health and Rehabilitation Sciences. She received her Master of Science in Physical Therapy from Washington University in St Louis, and then practised physical therapy for 4 years before returning to Washington University for her PhD in movement science under the advisement of Dr Shirley Sahrmann. Cara completed a postdoctoral fellowship focused on rehabilitation robotics with Dan Ferris PhD at the University of Michigan. She is actively involved in both the American Society of Biomechanics and APTA. Cara is currently the president of APTA’s Academy of Physical Therapy Research. The long-term goal of her research is to improve the lives of individuals with chronic MSK pain, and prevent or slow the progression of MSK damage through enhanced knowledge of joint function. Cara has published over 100 peer-reviewed journal articles spanning hip joint forces, movement analysis and gait. She has received research funding from multiple sources, including the National Institutes of Health and the National Science Foundation. Her current focus is on investigating the interaction of movement and morphology in the development of hip shape and pain.