Introduction

Urinary incontinence (UI) is defined by the International Urogynecological Association (IUGA) as the involuntary loss of urine, predominantly in women, and its prevalence increases with age, being the most common pelvic floor (PF) dysfunction (^{Haylen et al., 2010}). The global prevalence of UI ranges from 5% to 69% throughout a woman’s lifetime (^{Abrams et al., 2009}), leading to social and emotional discomfort for women with UI (^{Viana et al., 2014}), thus impacting the quality of life (QoL) (^{Viana et al., 2015}; ^{Da Roza et al., 2013}). Only 25% to 61% of women with UI seek treatment. Shame, lack of knowledge about treatment options, or fear of surgery may explain this reluctance to seek help (^{Portuguese Society of Gynaecology, 2018}).

Risk factors for UI can be intrinsic (race, genetic predisposition, anatomical or neurological alterations), gynaecological or obstetric (pregnancy, type of delivery, multiparity, post-pelvic surgery, and radiotherapy, pelvic organ prolapse), or other factors (age, comorbidities, obesity, constipation, smoking, occupational activities, urinary infections, menopause, and medication) (^{Pires et al., 2021}; ^{Frawley et al., 2021}; ^{Pires et al., 2020a}).

According to its aetiology and pathophysiology, UI can be classified into three types with different symptoms: Stress Urinary Incontinence (SUI) (involuntary loss of urine with physical exertion, such as coughing, sneezing, or sports activities), the most common type (33% to 50%); Urgency Urinary Incontinence (UUI) (involuntary loss of urine associated with an urgent need to urinate that is difficult to control); and Mixed Urinary Incontinence (MUI) (involuntary loss of urine associated with both urgency and increased intra-abdominal pressure) (^{Hagovska et al., 2017}; ^{Portuguese Society of Gynaecology, 2018}; ^{Whooley et al., 2020}).

UI poses a risk to QoL and often leads patients to anxiety, depression, and social isolation (^{Pierce et al., 2017}), as well as physical inactivity, affecting health-related QoL (^{Da Roza et al., 2012}).

Pelvic floor muscle training (PFMT) has been reported as effective in curing or improving UI symptoms in young, middle-aged, and older women with SUI or MUI, as well as in pregnant or postpartum women (^{Pires et al., 2020}b; ^{Dumoulin et al., 2017}; ^{Pires et al., 2020c}). Clinical practice guidelines recommend individual and supervised PFMT as the first-line treatment for women with UI (^{Dumoulin et al., 2017}; ^{Pires et al., 2020d}).

The aim of this study is to assess the effects of PF physiotherapy on pelvic function and QoL in women with UI, summarising and synthesizing the scientific evidence.

1. Methods

The systematic review was registered according to the PROSPERO protocol (CRD42023488377) and was conducted in accordance with PRISMA guidelines (^{Page et al., 2021}). The research was carried out in the following databases: PubMed, Scopus, and Web of Science, between January and April 2022. The keywords used were Physiotherapy, UI, and QoL, combined with Boolean operators (AND; OR). The search strategy (TS) used was: TS=(Physiotherapy* OR Pelvic floor muscle training) AND TS=(Urinary incontinence) AND TS=(Quality of Life) AND TS=(Randomized controlled trial OR RCT) AND TS=(Women OR Female), with filters for humans only, articles written in English and Spanish, from the last 5 years. The search was conducted by two independent researchers (EM, RV), who compared both results to check for overlap. Any discrepancies were discussed until a consensus was reached.

After the initial identification, duplicate articles were removed, and all titles and abstracts from the selected databases were screened. Then, potentially relevant studies were selected and retrieved, and the full texts were read to apply eligibility criteria according to the following inclusion criteria: women with UI; over 18 years old; community residents; receiving pelvic floor physiotherapy or under the supervision of a physiotherapist; randomized controlled trials (RCTs). The exclusion criteria were as follows: previous pelvic surgeries; pelvic organ prolapse (POP); pregnant women; on medication for UI; case studies; reviews and meta-analyses. Methodological quality was assessed using the PEDro scale, reported as a valid and reliable tool for measuring the methodological quality of RCTs. These parameters were independently evaluated by two authors (EM and RV), and all discrepancies were resolved.

2. Results

The flowchart of the research conducted is presented below (Figure 1). The characteristics of this study are shown in Table 1. After going through all these stages, 19 RCTs were selected for analysis. The sample size ranged from 31 to 600 women with UI, with participants aged between 20-35, 48-58, and 60-70 years. The most reported type of UI was SUI, with 11 studies (1, 2, 3, 4, 8, 10, 11, 13, 15, 16, 19), 3 studies focused on MUI (5, 6, 9), 2 assessed UI and sexual dysfunction (11, 12), 1 assessed UUI (6), and 5 assessed UI without specifying the subtype, with 1 (18) also evaluating fecal incontinence (FI) in addition to UI. The follow-up duration of the studies ranged from 4 weeks (4) to 36 months (12). There were various approaches, but no uniform standard for PFMT was identified.

Figure 1 PRISMA 2020 flow diagram for new systematic reviews that include database searches. 

The mean methodological quality score of the included studies was 8.42 ±1.73 (range 5-10) out of 10 points according to the ^{PEDro scale}. The most common methodological limitation among the studies was the lack of “blinded therapists,” which was nevertheless conducted by 10 studies (1, 3, 5, 6, 7, 9, 12, 15, 18, 19). The lack of “blinded assessors” was also a methodological limitation in 8 studies (2, 4, 8, 10, 11, 14, 16, 17) (Table 2).

To assess the parameters of muscle function, the following measurement instruments were used: perineometer (3, 11, 15, 16), dynamometer (6), and manometry (5, 13, 18), digital palpation using the Oxford Scale (3, 6, 13), digital palpation PERFECT (8, 15), Ortiz Scale (15), and transperineal ultrasound (6). To assess involuntary urine loss, the Pad test (5, 6, 7, 8) and a voiding diary (1, 6, 8, 13, 15) were used.

The measurement instruments used to assess sexual function were: FSFI (11) and ICIQ-FLUT SEX (6, 11). For the evaluation of UI symptoms and QoL: ICIQ - LUTSqol (6, 10, 17); ICIQ-UI SF (3, 5, 6, 10, 14, 15); PGI -I - Patients Impression of Improvement for Incontinence - (5); Australian Pelvic Floor Questionnaire (APFQ) (18); Incontinence Severity Index - ISI - (1); King’s Health Questionnaire (1, 15, 16); PISQ - 31 - Prolapse and Incontinence Sexual Function Questionnaire (12); SF-36 (12); EQ - ID (12); EQ - 5 D (12); E-PAQ (12); QoL short form - (7, 8, 14, 16); ICIQ-N (6); ICIQ - VS (6); Rosenberg Self-Esteem Scale (14); Geriatric Self Efficacy Scale (6); and Broom Self-Efficacy (6).

Different types of technology associated with PFMT were used: virtual reality (game therapy) (5); NeoControl chair (extracorporeal magnetic innervation) (19); 1 study that used an Easy K7 device that transmits low-frequency stimulation (11); and 2 studies that employed a mobile application (Tät) for the home self-management of PFMT (2, 10).

3. Discussion

This systematic review provided a comprehensive description of pelvic rehabilitation methodologies in promoting QoL in women with UI and highlighted the results related to PFMT.

Despite the heterogeneity in the assessment measures used to evaluate urinary symptoms, all studies demonstrated a reduction in the amount of involuntary urine loss, a decrease in the frequency of UI, an improvement in QoL in the PFMT groups following the intervention, and a significant increase in pelvic floor muscle (PFM) strength in the intervention groups before and after PFMT.

^{Sigurdardottir et al. (2019}) evaluated PFMT in the postpartum period and concluded that PFMT reduces the rate of UI and discomfort present in the postpartum phase. The strength and endurance of the PFM also increased regardless of whether they were performed individually or in groups; this improvement appears to be related to the physical contact with the physiotherapist. Teaching and assessing the contractility of the PFM were included to ensure correct performance, resulting in improved body awareness, structural support of the pelvic organs, and the ability to perform quicker automatic contractions of the PFM.

The study by ^{Hwang et al. (2019}) evaluated potential improvements from an 8-week program of transcutaneous electrical stimulation (TES) on the strength parameters of the pelvic floor and sexual function in women with UI. The outcome was an increase in PFM strength and also in the domain of sexual function improvement attributed to enhanced stimulation of the PFMs. The increased contractions of the PFMs and blood flow necessary during sexual activity, along with a decrease in fear of dyspareunia and urinary loss during intercourse, enable women to regain desire, arousal, and sexual satisfaction.

^{Jha et al. (2017}) also included in their protocol PFMT combined with electrical stimulation over 36 months, but no statistically significant differences were found compared to the group that performed isolated PFMT.

In the training programs by ^{Dumoulin et al. (2020}), individual versus group PFMT showed similar efficacy for all evaluated criteria (muscle function, UI treatment, and QoL), except for sexual issues associated with lower urinary tract symptoms. For these authors, the group approach allows for a rapid increase in the number of women treated with PFMT and makes access easier. Similarly, Dumoulin et al. (2017) noted that the impact of group PFMT is positive compared to individual PFMT sessions regarding the accessibility of continence care for women, being equally effective and more economical.

Other studies that combined biofeedback (BFB) with PFMT (^{Bertotto et al., 2017}; ^{Fitz et al., 2017}; ^{Hagen et al., 2020}) concluded that after 24 months, comparing women who underwent BFB in a clinical context and PFMT at home with those who only performed PFMT, improvements in UI were observed in both groups, indicating that supervised and protocolized PFMT with or without BFB provides benefits.

Improvements in muscle strength and EMG activity were reported in the PFMT group with BFB, particularly in pre-contraction, endurance, and maximum voluntary contraction (MVC) in postmenopausal women. According to this study, adding BFB to PFMT helps women control and become aware of their activities and muscle activation, thus managing potential losses during daily life activities (^{Bertotto et al., 2017}).

The literature shows that groups treated with BFB have greater progress in treating UI, likely due to the instruction on contraction in women assessed with low awareness of pelvic floor musculature (^{Castro et al., 2010}) and that BFB-assisted PFMT is more effective than isolated PFMT in improving clinical symptoms, uroflowmetry parameters, and electromyographic activity during urination (EMG) (^{Sam et al., 2022}).

In studies evaluating the effect of PFMT alongside vaginal tampon use compared to isolated PFMT, training effectiveness yielded similar results between the two training types regarding PFM strength and endurance, UI, and QoL. The progression was more rapid in the PFMT group with the use of a vaginal tampon. The innovation of the study was the use of a vaginal tampon in PFMT instead of vaginal cones, where the training involved pulling the tampon, thus rendering the weight of the vaginal cone ineffective (^{Orhan et al., 2018}).

Results from game therapy showed improvement in symptoms of urge incontinence, however, associating a game-form therapy with PFMT did not demonstrate better results than isolated PFMT (^{Bezerra et al., 2020}).

To compare the effects of PFMT with the abdomen-hypopressive technique in reducing urinary loss in women with UI, a reduction in symptoms was observed both in women who performed PFMT with the abdomen-hypopressive technique and those who only performed PFMT.

PFMT was superior to the abdomen-hypopressive technique in muscular parameters, symptom reduction of SUI, and QoL improvement. However, the reduction was significantly greater in women undergoing PFMT (^{Jose‐Vaz et al., 2020}). Other studies also corroborate better results from PFMT (^{Dumoulin et al., 2017}) due to the fact that the abdomen-hypopressive technique does not directly activate the contraction of the PFMs.

Studies evaluated the impact of isolated PFMT versus PFMT combined with transverse abdominal muscle (trA) activation on QoL in women with UI concerning the number of childbirths, showing that PFMT was similar for both groups. Both training types yielded positive results; however, synergistic training of the PFMs with the trA muscle was more effective in muscle parameters and QoL (^{Ptak et al., 2019}). Other authors reported that simultaneous contraction of the trA and PFMs promotes continence (^{Junginger et al., 2010}).

For the efficacy of dynamic lumbar-pelvic stabilization exercises in treating women with UI, compared to isolated PFMT, a similar PFMT program was implemented in both groups, and the authors concluded that there were no statistical differences in the severity of losses between the two groups. However, 90 days post-intervention, the experimental group showed a reduction in the frequency of losses and an improvement in QoL (^{Abreu et al., 2017}).

In another study, the authors investigated the effect of strengthening exercises for the PFMs and hip muscles (adductors and abductors, gluteus maximus, and medius) compared to the isolated strengthening of the PFMs in treating SUI. According to the results, there were no significant differences between the two groups regarding functional assessment of the PFMs, perineometry, and voiding diary, as well as QoL. Thus, hip exercise training did not translate to greater strengthening of the PFM. However, the important factor of this training was the increased synergy of the pelvic muscles due to the anatomical relationship of the hip muscles with the PFMs, thus contributing to the continence mechanism and greater efficacy of physiotherapy in treating UI (^{Marques et al., 2019}).

In the same line of training, authors like ^{Lausen et al. (2018}) associated the positive effects of modified Pilates training with PFMT in treating UI. These benefits may have arisen from participation in classes that positively influenced attitudes toward exercise, diet, and well-being. In women with mild urinary loss symptoms, the advantage of performing modified Pilates training lies in improving self-esteem, reducing social embarrassment, lowering the impact on daily living activities, and improving personal relationships.

Participation in PFMT is supported by the Cochrane review, which supports the current grade A recommendation for PFMT as a first-line treatment for women with UI (^{Cacciari et al., 2019}).

Regarding studies with long-term follow-up, Asklund et al. (2017) and ^{Hoffman et al. (2017}) evaluated the effects of a PFMT program using a mobile application in women with SUI, yielding significant and clinically relevant results that could serve as a first-line treatment for women with UI concerning long-term follow-up (Hoffman et al., 2017).

In terms of QoL, studies have shown improvements when women are integrated into PF physiotherapy programs either individually or in groups; however, women participating in group PFMT report a better perception of improvement in urinary symptoms and QoL (^{Abreu et al., 2017}; ^{Dumoulin et al., 2020}; Dumoulin et al., 2017; ^{Lausen et al., 2018}).

Similar results were obtained regarding improvements in QoL in treating UI in both the group receiving extracorporeal magnetic innervation (ExMI) and the group receiving PFMT, both in terms of the severity of UI and emotions, as well as social limitations. However, PFMT as a treatment for UI has fewer contraindications than therapy by ExMI (^{Weber-Rajek et al., 2020}).

Limitations

The variety and array of interventions, including techniques, procedures, and protocols in PF physiotherapy, as well as potentially smaller sample sizes, may not provide conclusive data regarding the most effective intervention. It is also worth mentioning the subjectivity of certain assessment instruments that may have influenced the study outcomes.

Conclusion

After conducting this study, it can be concluded that PF physiotherapy intervention, utilizing PFMT in women with UI, should be considered an effective treatment, demonstrating promising results in increasing PFM strength, reducing involuntary urine loss, and improving QoL.

Author contributions

Conceptualization, E.M., T.P. and R.V.; data curation, E.M.; formal analysis, T.P. and P.P.; funding acquisition, E.M.; investigation, E.M., T.P. and P.P.; methodology, E.M., F.S., P.P. and R.V.; project administration, E.M. and R.V.; resources, E.M. and T.P.; software, E.M.; supervision, E.M., T.P., P.P. and R.V.; validation, E.M., T.P. and R.V.; visualization, E.M., T.P., F.S., P.P. and S.V.; writing-original draft, E.M. and T.P.; writing-review and editing, E.M., T.P., F.S., P.P., S.V and R.V.

Conflicts of interest

The authors declare no conflict of interest.