Spinal‐Related Musculoskeletal Determinants of Functional Abdominal Bloating and Distension: A Narrative Review

ABSTRACT

Background and Aims

Functional abdominal bloating and distension disorder (FABD) is a single‐syndrome gastrointestinal disorder of the “gut–brain axis,” and is associated with a negative impact on adult's well‐being. Abdomino‐phrenic dyssynergia has recently been recognized as an important contributing factor to FABD, yet the influence of other spinal musculoskeletal determinants of this gastrointestinal disorder is not known. Our aim was to qualitatively explore spinal musculoskeletal determinants and propose research on potential new treatments for FABD.

Methods

In this narrative review, observational and intervention studies describing terminology, proposed pathophysiology, and interventions with focus on modifiable musculoskeletal determinants of FABD were reviewed from inception through 2023. Databases of PubMed, Scopus, Google Scholar, and ISI Web of Science were searched using the following keywords: “functional abdominal bloating,” “abdominal bloating,” spine,” Abdomino‐phrenic dyssynergia,” “abdominal wall,” “pelvic floor,” “back extensor muscle.”

Results

This review included 65 studies. These studies were explored in three sections: Abdomino‐phrenic dyssynergia, pelvic floor function, and sagittal alignment of spine. Although most of included articles reported APD as the main contributing factor to FABD, other spinal‐related musculoskeletal factors, abdominal muscle weakness, pelvic floor dyssynergia, and spinal malalignments were considered. These musculoskeletal factors were reviewed as both evidence of FABD (direct evidence) and other disorder of gut–brain interactions (DGBIs) (indirect evidence).

Conclusion

Preliminary evidence suggests spinal musculoskeletal factors contribute to FABD; however, more high‐quality observational studies exploring relationships between FABD and spinal‐based musculoskeletal factors are needed.

Summary

What is known

• Abdomino‐phrenic dyssynergia has recently been recognized as an important contributing factor to functional abdominal bloating and distension (FABD),(FABD), yet the influence of other spinal musculoskeletal determinants of this gastrointestinal disorder is not known.

What is new

• Spinal‐related musculoskeletal factors may contribute to FABD. Further study is needed to better understand how spinal musculoskeletal determinants impact FABD.

• What is the clinical implication: Because musculoskeletal determinants can be considered as potential risk factors for FABD, it is possible that physical therapy exercise‐based interventions may be helpful.

1. Introduction

Functional abdominal bloating (FAB) is a common disorder of gut–brain interactions (DGBIs) defined as a subjective sensation of increased abdominal pressure that may or may not be associated with visible abdominal enlargement and distension [1]. FAB associated with distention is named functional abdominal bloating and distension (FABD) and affects up to 30% of adults over the world [2]. Although FABD occurs in every age group, its highest prevalence is between the third and fifth decades of life and prevalence decreases with age [3]. FABD is more common in females than males (female to male ratio is 2–1) [1]. Females report greater severity of symptoms and seek healthcare more frequently for FAB compared with males [1, 4]. Adults with FABD experience physical and psychological complications, including stomach pain, discomfort, stress, anxiety, and depressive disorders that have a negative impact on activities of daily living and quality of life [5]. The cause of FABD is not well established and recently thought to be associated with abdomino‐phrenic dyssynergia [6] and other factors including motility disturbance of the gut, altered mucosal and immune function, altered gut microbiota, and visceral hypersensitivity [7]. Current management of DGBIs, including FABD, consists of antibiotics to alter the gut microbiome, neuromodulator medications, and dietary interventions [1]. However, satisfaction with current treatments is poor [8, 9, 10, 11], highlighting the need to investigate other potential contributing factors that could be addressed to improve outcomes.

Musculoskeletal determinants may be part of the pathogenesis of FABD. The purpose of this review is to describe the terminology and pathophysiology of FABD with a focus on the evidence for spinal musculoskeletal determinants of FABD. Although abdominal bloating and distension can be considered as a single subgroup of DGBIs, these gastrointestinal symptoms often coincide with other DGBIs especially irritable bowel syndrome (IBS) [12] and functional constipation (FC). Thus, our review includes observational and intervention research studies conducted in adults with IBS, FAB, functional dyspepsia, and intestinal dysmotility. We will explore spinal musculoskeletal determinants and propose research on potential new treatments for FABD.

2. Search Strategy

A comprehensive search was performed in PubMed, Scopus, Google Scholar, and ISI Web of Science from inception through 2023. Terms of “functional abdominal bloating,” “abdominal bloating,” “functional abdominal bloating and distension,” spine, “Abdomino‐phrenic dyssynergia,” “abdominal wall,” “pelvic floor,” “back extensor muscle” were used as search terms. The reference lists of included studies were scanned for ensuring a comprehensive study search.

2.1. Inclusion and Exclusion Criteria

Original and review articles related to terminology, pathophysiology, and management of DGBIs were included. We excluded non‐English reports, books, abdominal bloating and distension with nonfunctional etiology, bloating and distension related to children and adolescents, case reports, and letter to editors.

2.2. Study Selection

Obtained evidence from the databases and also from other sources were screened using EndNote (version 9.3.3, Thomson Reuters). After duplication deletion, titles and abstracts of all identified studies that potentially meet the study aim were screened and unrelated evidence was excluded. Finally, 65 studies were included and investigated (Figure 1).

Figure 1.

Flow chart of the process of literature selection.

3. Definition of FABD

DGBIs are diagnosed by a group of symptoms rather than a singular pathoanatomic or pathophysiologic etiology based on the gold standard international diagnostic Rome IV criteria [13]. Functional bowel disorders are a subset of DGBIs with symptoms related to the middle or lower gastrointestinal tract [14] and including IBS, functional diarrhea, FC, FAB, and unspecified functional bowel disorders [13]. FAB is defined as a subjective sensation of trapped gas or increased abdominal pressure, with nearly 50% of patients with FAB reporting objective increased abdominal girth (abdominal distension) or FABD [1]. FABD can be diagnosed as a single entity, although it may coexist with other functional bowel disorders [1]. According to the Rome IV criteria, FABD is associated with the onset of symptoms at least 6 months before diagnosis and the existence of recurrent feeling of bloating or distension in the last 3 months [1, 13].

4. Pathophysiology of FABD

Different mechanisms have been proposed as the pathophysiology of FABD and include the motility disturbance of the gut, altered mucosal and immune function, altered gut microbiota, and visceral hypersensitivity [7]. In response to a sensation of discomfort or distension, in patients with FABD, the peripheral gut sensation signals the brain, which in turn influences the endocrine, humoral, metabolic, and immune systems [6]. This bidirectional neurohumoral communication between the gut and brain is named “gut–brain axis” [15], and can lead to hypersensitivity, similar to that seen in IBS, where the bloating sensation occurs even when there is normal or only mildly increased amounts of gas or bowel contents [16]. Clinical presentation of FABD includes a bio‐psychosocial model [15], and adults with FABD often complain of psychological symptoms such as depression or anxiety [7] that can indicate dysregulation of the gut–brain axis [17].

Abdomino‐phrenic dyssynergia is currently considered a major cause of FABD. Abdomino‐phrenic dyssynergia is a maladaptive motor response between the abdominal muscles, intercostals, and the diaphragm postprandial that results in abdominal distension [6]. In a healthy person, postprandial contraction of the abdominal muscles is accompanied by an upward shift and relaxation of the diaphragm to accommodate the ingested volume without abdominal protrusion [12]. In response to the ascending diaphragm and resultant decrease in pulmonary cavity space, contraction of the intercostal muscles cause the costal wall to move upward and outward to restore pulmonary cavity space and normal breathing [18]. This adaptive postprandial response is mediated by the viscerosomatic response, where mechanoreceptors in the gut respond to changes in gut content and alert the nervous system, where signals are processed and executive efferent gut actions occur [19]. One proposed hypothesis for FABD is dysfunctional coordination between the diaphragm and abdominal muscles postprandial. In people without FABD postprandial, the diaphragm relaxes and ascends allowing room for gastrointestinal contents and the abdominals contract, which in turn promotes gut motility [12]. In people with FABD, an appositive reaction occurs, the diaphragm contracts and descends into the abdominal cavity and the abdominal wall relaxes leading to distention [20].

5. Rationale for Role of Behavioral Treatments Including Spinal Musculoskeletal Determinants for FABD

The “muscular box” including the abdominal muscles anteriorly, axial spine muscles posteriorly, diaphragm superiorly, and pelvic floor muscles inferiorly is important for normal gut function due to its anatomical proximity to the gastrointestinal tract [21]. This “muscular box” which is also important in trunk control and stability is often referred to as the muscular “core” [22] (Figure 2).

Figure 2.

Proposed musculoskeletal factors for functional abdominal bloating and distension.

The core muscles affect the distribution of abdominal contents and control intra‐abdominal pressure, which modulates gut function [23, 24, 25]. Weakness, inability to relax, or impaired coordination between the diaphragm, abdominal, and pelvic floor muscles may impair the viscerosomatic loop, leading to impaired gut function; or it is possible that the reverse is true and visceral hypersensitivity may cause an abnormal viscerosomatic response activating abdomino‐phrenic dyssynergia and distention [21, 26]. Furthermore, decreased abdominal and back extensor muscle mass, strength, and endurance affects sagittal spinal alignment [27] and consequently impacts gastrointestinal function [25]. Excessive thoracic hyperkyphosis decreases vertical abdominal cavity [20], which displaces abdominal contents anteriorly and increases the likelihood of bloating. Likewise, hyperlordosis redistributes abdominal contents and has been introduced as a determinant of abdominal wall protrusions [16].

The pelvic floor muscles, levator ani, puborectalis, pubococcus, iliococcus protect the pelvic organs, control urination and defecation, and provide general support inferiorly for the intra‐abdominal contents [28]. The pelvic floor normally moves in tandem with the diaphragm to maintain intra‐abdominal pressure, which is important for gastrointestinal function and trunk stabilization [29]. During inspiration, the diaphragm contracts and descends, the pelvic floor muscles relax and also descend, causing downward displacement of pelvic organs. During expiration, the diaphragm relaxes and ascends while the pelvic floor ascends and simultaneously co‐contracts with the abdominal muscles, which preserves intra‐abdominal pressure. These co‐contractions of the pelvic floor with the diaphragm or abdominal muscles are important to support the pelvic organs and control urination and defecation [30, 31]. The contractions of the pelvic floor and abdominal muscles increase intra‐abdominal pressure that facilitates colorectal movements and bowel transits [32]. The absence of coordination between pelvic floor muscles for correct and on‐time relaxation or contraction is named as dyssynergic defection [26] and can lead to difficulty emptying the rectum [33].

6. Observational and Intervention Studies on Musculoskeletal Factors and FABD

Several observational and intervention studies have been reported in relation to FABD (direct evidence) or other DGBIs (indirect evidence) that include abdominal distention and bloating as a symptom.

Observational studies on abdominophrenic dyssynergia:

Abdomio‐phrenic dyssynergia was confirmed in several studies including patients with IBS, FAB, functional dyspepsia, and intestinal dysmotility [18, 34, 35, 36, 37, 38, 39] using electromyography (EMG) and imaging techniques to identify responses. Because these studies were discussed completely in previous reviews [6, 16], we summarized them in Table 1. This abnormal response was confirmed in another small cross‐sectional study [40] in healthy adults (n = 42) investigating the responses of the diaphragm and abdominal muscles to colonic gas injection during different conditions. EMG activity of the diaphragm and abdominal wall muscles were recorded with external sensors and abdominal girth was measured in participants in erect standing and supine postures before and after gas injection into the colon. Abdominal CT scans were obtained before and after gas injection in a sample of eight subjects. In the standing position during gas injection, abdominal muscle activity increased up to 16 ± 4%, and diaphragm inhibition was associated with abdominal muscle contraction (r = 0.89, p < 0.01). When participants were supine following gas injection, EMG abdominal activity did not change from resting levels, but CT scan analysis showed the diaphragm descended, and EMG activity increased 15 ± 6%. Abdominal girth also increased 8.6 ± 1.4 mm, suggesting contraction and downward movement of the diaphragm is a primer for abdominal distension.

Table 1.

Summary of studies showing abdomino‐phrenic response.

Author (year)	Population	Stimulus of bloating	Measurements	Results
Tremolaterra (2006)	Adults with abdominal bloating (IBS: n = 8; functional bloating: n = 4); healthy (n = 12)	Rectal gas infusion for 1 h	1. Abdominal girth 2. Abdominal muscle activity	At the same infused gas levels, patients showed significant abdominal distension (11 ± 1 mm; p < 0.05). This distension was associated with reduced activity of the internal oblique (26% ± 7%; p < 0.01 vs. basal) [34].
Accarino (2009)	56 patients with abdominal bloating: (Functional intestinal disorder (n = 47); intestinal dysmotility (n = 9); Healthy (n = 12)	—	For patients, computed tomographic scans were obtained before and during a severe bloating episode. For healthy adults, control scans were recorded.	During severe bloating, patients with dysmotility exhibited anterior wall protrusion (23 ± 4 mm; p < 0.001 vs. basal) associated with cephalic displacement of the diaphragm. By contrast, in patients with functional intestinal disorder, abdominal distention (14 ± 2 mm anterior wall protrusion; p < 0.001 vs. basal) was related to diaphragmatic descent (–12 ± 3 mm; R _ –0.62; p < 0.001) [35].
Villoria (2011)	20 patients with abdominal bloating (IBS with constipation (n = 15); functional bloating (n = 5); Healthy (n = 15)	Rectal gas infusion for 1 h	1. Abdominal girth 2. Abdominal muscles and diaphragm activity	The colonic load resulted in increased girth, relaxation of diaphragm, and increased abdominal muscle tone in healthy adults. At the same colonic load, bloating patients developed greater abdominal distension that was associated with diaphragm contraction/decent and relaxation of abdominal muscle [18].
Burri (2012)	Healthy subjects (n = 9)	Colonic gas infusion	1. Abdomino‐thoracic girth 2. EMG of diaphragm, abdominal, and intercostal muscles	Gas infusion lead to anterior abdominal wall contraction (18 ± 1% increment; p < 0.001) with modest increase in abdominal girth (4.9 ± 0.9 mm; p = 0.001), diaphragmatic relaxation (by 15 ± 1%; p < 0.001), and intercostal contraction (by 19 ± 2%; p < 0.001) with increased thoracic perimeter (by 2.0 ± 0.5 mm; p = 0.009) [36].
Burri (2014)	Patients with postprandial bloating (n = 10); healthy subjects (n = 12)	A test meal	EMG responses of the anterior wall of the abdomen and the diaphragm	Normal abdominal wall accommodation including relaxation of the diaphragm (reduced EMG: 15 ± 5%), contraction of upper abdominal wall muscles (25 ± 9% increase) and no change in lower rectus and internal oblique activity were recorded in healthy subjects. Patients showed diaphragmatic contraction (14 ± 3% increment; p < 0.01 vs. healthy subjects) and upper abdominal muscle relaxation (9 ± 4% inhibition; p < 0.01 vs. healthy subjects) [37].
Barba (2015)	Patients with FGIDs (n = 45)	—	CT scan and EMG of abdomino‐thoracic wall during basal (without abdominal distension) and severe distension	Abdominal distension was associated with diaphragm contraction (19% ± 3% increase in EMG and 12 ± 2 mm descent; p < 0.001 vs. basal values) and intercostal contraction (14% ± 3%increase in EMG and 6 ± 1 mm increase in thoracic antero‐posterior diameter; p < 0.001 vs. basal values). Severe distension was also associated with anterior abdominal wall protrusion (32 ± 3 mm increase in girth; p < 0.001 vs. basal) [38].
Livovsky (2021)	Healthy females (n = 16)	A meal load	Sensation of bloating, abdominal girth	Compared with diaphragmatic relaxation, diaphragmatic contraction was associated with diaphragmatic descent (by 21 + 3 mm; p = 0.001), abdominal distension (32 + 5 mm girth increase; p = 0.001), more intense sensation of bloating (7.3 + 0.4 vs. 8.0 + 0.4 score; p = 0.010) [39].

Abbreviations: EMG, electromyography; FGIDs, functional gastrointestinal disorders; IBS, irritable bowel syndrome.

Abdomio‐phrenic dyssynergia may result in abdominal muscle weakness. Flintrop et al. [41] investigated the association between muscle length and strength of diaphragm, abdominal and respiratory muscles in 22 patients with chronic ascites. Similar to FABD, in ascites, the size of abdominal cavity increases and leads to stretch of the abdominal and respiratory muscles. Inspiratory and expiratory muscle strength and length were measured before and after fluid removal, and the strength of the abdominal and respiratory muscles did not change, suggesting that increased length in the abdominal muscle did not change abdominal strength. In contrast with these findings, Sullivan et al. [42] compared body mass index, abdominal muscle strength (sit up movement), and abdominal girth (during bloating episodes) between patients with primary complaint of nonorganic bloating (n = 46), patients with no bloating (n = 62) and sex/aged matched healthy controls (n = 24). Bloating patients had weaker abdominal muscles than controls (p < 0.012), and abdominal girth increased. This result was confirmed in a case–control study of middle‐aged females (with and without FAB) [43]. Furthermore, abdominal muscle weakness was reported in 45 patients with FAB, supporting the important role of these muscles in normal gut function [43].

6.1. Observational Studies on Sagittal Alignment

Alvarez et al. [44] report that voluntary hyperlordosis was associated with exaggeration of bloating or distension. This result was confirmed in Maxton's study [45] where lumbar lordosis (using lateral standing X‐ray), diaphragm position, and abdominal girth (in lying and standing) were measured and compared between 20 patients with IBS and 20 controls. Compared with the control group, the IBS group showed an increase in abdominal girth (abdominal distension) in both direct and radiological measurements. There were no significant correlations between lordosis and distension, but voluntary abdomen protrusion while standing and lying in the CT scan was associated with diaphragmatic descent and hyperlordosis in the IBS group. This evidence suggests poor sagittal alignment may contribute to abdominal bloating and distension.

Several studies have reported associations between musculoskeletal factors of the spine and gastroesophageal reflux disease (GERD) [23, 24, 25]. It is hypothesized that flexed posture can increase intra‐abdominal pressure, which in turn induces pressure on the esophagus and predisposes patients to GERD [23]. Miyakoshi et al. [23] examined associations between spinal factors (thoracic and lumbar kyphosis, vertebral fracture) with GERD in 112 patients with osteoporosis and reported GERD had significant associations with decreased lumbar lordosis (r = 0.57, p = 0.0001), number of thoracic (r = 0.21, p = 0.02) and lumbar (r = 0.47, p < 0.0001) vertebral fractures. These results were confirmed in other cross‐sectional [24] and longitudinal studies [25], reporting an increase in spinal kyphosis was a contributing factor for GERD in adults.

6.2. Observational Studies on Pelvic Floor

A recent review of Azpiroz et al. [6] reported pelvic floor muscle dyssynergia as a contributing mechanism of bloating and distension in DGBIs. Pelvic floor dyssynergia, with impaired relaxation and coordination of the pelvic floor and abdominal muscles during bowel evacuation, has been reported in 50% of people with AD and 62% of people with abdominal bloating [46].

One study investigated anorectal function in patients with constipation and categorized 88 patients as those with bloating and distension (n = 53) and those with bloating without distension (n = 35). The distension group showed prolonged balloon expulsion time and higher resting sphincter pressure than the non‐distension group, indicating ineffective gas evacuation as a mechanism of AD in patients with constipation [47]. Another study compared the Recto‐anal‐inhibitory reflex (RAIR), a relaxation reflex following rectal distention, in females with chronic constipation with (n = 55) and without AD (n = 20) and report the group with AD reached anal relaxation with more delay than group without AD, p = 0.03, and exhibited longer time to maximal relaxation. Disturbance in the RAIR may lead to prolonged gas evacuation and abdominal distension [48].

6.3. Interventional Studies on Biofeedback

Use of real‐time EMG biofeedback was investigated to improve coordination between the diaphragm and abdominal muscles and correct abdomino‐dyssynergia in 15 patients with DGBIs [38]. Participants received respiratory muscle EMG biofeedback (range of sessions: 1–3 with duration 40 min) with instructions to reduce intercostal and diaphragm activity and increase abdominal muscle contraction during expiration. After biofeedback training, participants demonstrated reduced activity in the intercostals and diaphragm (19% and 18%, respectively) and increased activity of the internal oblique muscles (52%). Participants reported clinical reductions in AD (by 25 ± 3 mm) (p < 0.009 vs. pretreatment for all). These results were confirmed in another randomized trial that enrolled patients with visible AD post prandial (n = 44, age: 21–74 years old) into a biofeedback intervention or placebo group. Both intervention and control groups used biofeedback and abdomino‐thoracic wall EMG activity was recorded during study sessions. The intervention group received instruction and training on diaphragm and intercostal muscle relaxation while increasing abdominal muscle activity during exhalation, and the placebo group received simethicone (a medication to relieve painful pressure caused by gas in the stomach and intestines) while wearing biofeedback sensors without training. Compared with placebo, biofeedback decreased activity of intercostalis (45%), and increased activity of abdominal muscles (101%) (p < 0.001). Biofeedback training improved AD 56% (from 4.6 ± 0.2 to 2.0 ± 0.2 mm), but the placebo group had a reduction only 13% (from 4.7 ± 0.1 to 4.1 ± 04 mm) (p < 0.001) [49].

6.4. Interventional Studies on Diaphragm Breathing

Diaphragmatic breathing exercise was investigated in a randomized waitlist control trial among 15 subjects with GERD compared with 21 controls. The intervention group received 4 weekly sessions of diaphragmatic breathing for 30 min for 4 weeks. Belching frequency and GERD symptoms in the intervention group were significantly reduced compared with the control group and this improvements were preserved 4 months after treatment [50]. This result was confirmed in a systematic review investigating the effects of breathing training on GERD [51]. Another meta‐analysis including three high‐quality studies reported that diaphragmatic breathing had a beneficial effect on lower esophageal pressure in GERD patients (weighted mean difference = 1.36, 95% CI: 0.82–1.91, p < 0.01) [52].

6.5. Interventional Studies on Physical Activity

Physical activity can target gut–brain axis by reducing sympathetic tone and increase parasympathetic activity [53]. Hosseini‐Asl et al. [54] studied a possible prokinetic effect of walking on the gut. They categorized adults with FAB into interventional (n = 45) and control groups (n = 49) and compared the effects of a 10–15 min walking program after each meal for 4 weeks to prokinetic medications in the control group. Although both groups demonstrated within‐group improvements in gastrointestinal symptoms (p < 0.001), a greater reduction in bloating severity in the interventional group was reported compared with the controls (p = 0.002). In one study, a gas infusion was performed in eight patients with bloating. The assessments of perception (0–6 scale) and abdominal girth were performed during pedaling compared with rest as a control. An improvement in bloating and distension was reported during pedaling periods. This study showed positive effects of physical activity on intestinal gas clearance [55]. This result was confirmed by Johannesson et al. [56] reporting an increase in physical activity improved gut symptoms in IBS.

Positive effects of yoga in different functional gastrointestinal disorders including IBS and functional dyspepsia have been reported [57, 58, 59, 60]. One study of adults with IBS reported the feasibility of an 8 week virtual yoga program compared with an advice‐only control. Compared with control, the virtual group significantly decreased the severity of IBS symptoms (p = 0.02) [57].

6.6. Interventional Studies on Pelvic Floor Biofeedback

A study of 155 patients with DGBI, whose main complaint was abdominal bloating, investigated the effects of pelvic floor muscle biofeedback using an intra‐anal EMG probe on bowel function. The intervention reduced bloating, improved stool frequency, and decreased laxative usage [61]. Two other studies reported pelvic floor muscle training with or without biofeedback improved pelvic floor muscle contraction and relaxation, and decreased associated symptoms including abdominal bloating/distension in people with inflammatory bowel disease [62, 63].

Rao et al. [64] compared biofeedback (manometric‐assisted anal relaxation and simulated defection training) with sham biofeedback and standard care in 77 adults with chronic constipation and dyssynergistic defecation. After 3 months, the biofeedback group had greater clinical improvements, p < 0.001, and decreased balloon expulsion time, p = 0.02, compared with standard care and sham biofeedback. Additionally, the biofeedback group reported improvements in daily bowel movements without feeling incomplete emptying (p < 0.02) and better global satisfaction in symptoms (p = 0.04) compared with both other groups.

7. Proposed Spinal Musculoskeletal‐Focused Clinical Algorithm for FABD

Because spinal musculoskeletal factors can be considered potential risk factors for FABD (Figure 2), physical therapists can assist in the management of this functional disorder. Based upon the observational and interventional research on FABD, including previous evidence for other similar DGBIs with bloating and distention, we propose an evidence‐based therapeutic algorithm including modifiable spinal musculoskeletal factors in the management of FABD (Figure 3). Adults with primary complaint of FABD screened by a gastroenterologist may be considered for spinal musculoskeletal‐focused treatment (Figure 3A).

Figure 3.

Proposed clinical algorithm for functional abdominal bloating and distension (A) Clinical pathway for gastroenterologist; (B) an evidence‐based musculoskeletal therapeutic algorithm for physical therapist. APD, abdomino‐phrenic dyssynergia; EMG, electromyography; FABD, functional abdominal bloating and distension; PT, physical therapy.

A comprehensive musculoskeletal evaluation performed by a physical therapist may include assessment for abdomino‐phrenic dyssynergia, trunk and pelvic floor muscle function, and spinal alignment. According to the evaluation, an individualized treatment plan including biofeedback and training to reduce abdomino‐phrenic dyssynergia, improve muscle function in the core abdominal wall, posterior back extensors and pelvic floor muscles, and postural correction may be proposed. Therapy with a focus on improving coordination of the diaphragm, abdominal and pelvic floor muscle strengthening, biofeedback, postural education, core strengthening, thoracic/rib mobility may all be included as indicated to reach treatment goals to reduce symptoms of FABD (Figure 3B).

8. Future Directions for FABD

There is preliminary evidence to suggest that spinal musculoskeletal contribute to FABD; however, more high‐quality observational studies exploring associations between FABD and spinal‐based musculoskeletal factors are needed. Pelvic floor training focusing on correction of pelvic floor/thoraco‐abdominal dyssynergia and FAB and AD may be helpful. Abdomino‐phrenic dyssynergia may be modifiable with interventions targeting respiratory function utilizing biofeedback equipment; however, there is no standard of care protocol [6]. Considering APD is an important mediator of FABD, a high‐quality randomized controlled trial with an exercise design focusing on diaphragm relaxation simultaneously with abdominal muscle strengthening may be indicated. Ultrasound imaging can be used to provide visual biofeedback and improve performance in the ability to relax the diaphragm and activate abdominal muscles [65].

9. Conclusion

FABD has been reviewed as a common and complex gastrointestinal complaint with few evidence‐based treatment options. Our review of the literature provides evidence of beneficial clinical effects of biofeedback, core muscle training, and physical activity on gastrointestinal symptoms in different DGBIs with bloating and distention; however, many of these treatments have not been studied in adults with FABD. Preliminary evidence indicates musculoskeletal factors especially abdomino‐phrenic dyssynergia and including spinal‐related musculoskeletal factors may contribute to FABD. Further study is needed to better understand how spinal musculoskeletal factors impact FABD and investigate behavioral treatment including spinal muscle‐based interventions for FABD.

Author Contributions

Rezvan Ghomash Baf Zadeh: investigation, methodology, project administration, writing – original draft, writing – review and editing, data curation. Tayebeh Roghani: conceptualization, methodology, investigation, project administration, writing – original draft, writing – review and editing, data curation, supervision. Amy Gladin: investigation, writing – original draft, writing – review and editing, data curation, project administration, methodology. Wendy B. Katzman: methodology, data curation, project administration, writing – original draft, writing – review and editing, investigation. Fateme Bokaee: investigation, writing – original draft, writing – review and editing, project administration, methodology. Peyman Adibi: conceptualization, methodology, supervision, writing – original draft, writing – review and editing, project administration.

Conflicts of Interest

The authors declare no conflicts of interest.

Transparency Statement

The lead author Tayebeh Roghani affirms that this manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.

Data Availability Statement

The data that support the findings of this study are available from the corresponding author upon reasonable request.