Comparison of 90-90 ball and balloon exercise versus Kegel’s exercise on pelvic floor muscle strength and quality of life among postpartum women with stress urinary incontinence—a randomized clinical trial protocol

Abstract

Background

Stress urinary incontinence (SUI) is one of the notable problems in postpartum women. Even though Kegel’s exercise (KE) is a universally followed pelvic floor exercise for SUI, it is tough to perform as patients find it hard to identify the correct tiny muscles to contract. Co-contraction of the pelvic diaphragm during 90-90 ball balloon exercises (BBE) will work against IAP, and that produces a more controlled action of pelvic floor muscles. This study aims to compare the effectiveness of 90-90 BBE vs. KE over pelvic floor muscle strength (PFMS) and quality of life (QoL) in women with postpartum SUI.

Method

Eighty-six postpartum women with SUI will be screened and recruited through purposive sampling. Subjects will be divided into experimental and control groups through block randomization. The control group will receive KE along with the Knack technique (KT); meanwhile, the experimental group will receive 90/90 BBE with KT (10 repetitions, 3 sets a day, 3 days a week, 8 weeks). Outcome measures are pelvic floor muscle strength (PFMS), quality of life, 1-h pad test, and global rate of change, which will be taken at pre- and post-intervention at the 8th week, 3rd month, and 6th month follow-up. Parametric or nonparametric statistical tests will be used based on the normal distribution of data. The result will be presented in the form of a 95% confidence interval and P value.

Discussion

This trial will provide novel evidence comparing a commonly used exercise (Kegel’s) with the 90-90 ball and balloon exercise, a physiologically guided approach targeting pelvic floor–abdominal synergy. If effective, this intervention may offer an easier and potentially more acceptable alternative to postpartum women with stress urinary incontinence. However, the interpretation of findings should consider that the sample size estimation was based on pre–post data, which may overestimate the true effect.

Clinical trial registration

CTRI—Clinical Trial Registry of India (ICMR)—Reg.No: CTRI/2024/06/069047. Trial registered prospectively. Registered on 18.06.2024.

Introduction

Background and rationale

Stress urinary incontinence (SUI) is defined as the involuntary leakage of urine during activities that increase in intra-abdominal pressure, such as coughing, sneezing, or exertional tasks [1, 2]. Pregnancy and spontaneous vaginal delivery are major contributing factors, in addition to aging and strenuous activity [3]. A hospital-based study in Jaipur, India, reported that among 322 women with urinary incontinence, 55.2% had symptoms, of which 74.1% were SUI, and the prevalence was highest among postpartum women [4]. A systematic review and meta-analysis further identified normal vaginal delivery, pregnancy-related weight gain, episiotomy, and forceps delivery as major risk factors [5]. Mechanistically, SUI is associated with reduced bladder neck support and decreased urethral closure pressure in the presence of elevated intra-abdominal pressure [6–9].

SUI negatively impacts psychosocial well-being, often leading to anxiety, depression, reduced self-esteem, and impaired sexual health, while cultural barriers make disclosure difficult [10–12]. Pelvic floor muscle strengthening exercises (PFMSE), particularly Kegel’s exercises (KE), remain the most commonly recommended non-invasive treatment [9, 13]. However, success rates vary widely (27–75%) [14, 15], with only 25–50% of women able to perform KE correctly [15], and additional cultural challenges exist in India [16, 17]. The Knack technique (KT), involving anticipatory pelvic floor contraction before activities that raise intra-abdominal pressure, has also shown benefits in daily and professional life [18–20]. Furthermore, studies indicate that training the transversus abdominis (TrA) may indirectly enhance pelvic floor activation by increasing intravaginal pressure and bladder neck elevation [21–24]. Recent evidence also highlights the importance of improving synergy between the diaphragm and pelvic floor to facilitate voluntary contractions in women with dysfunction [25].

The 90-90 ball and balloon exercise (BBE) enhances pelvic diaphragm and abdominal muscle function by optimizing breathing and postural stability, with demonstrated effects on respiratory strength and endurance [26, 27]. Expiratory co-contraction of abdominal and pelvic floor muscles during 90-90 BBE may help control intra-abdominal pressure [28], offering an alternative mechanism to strengthen pelvic floor function. Although KE is widely used, its limitations in execution and lack of diaphragmatic integration may restrict outcomes [25, 27, 29]. No published evidence currently exists on the impact of 90-90 BBE on pelvic floor muscle strength (PFMS) or SUI in postpartum women. Therefore, the study aims to compare the effectiveness of the 90-90 ball and balloon exercise (BBE) versus Kegel’s exercise (KE), both combined with the Knack technique, on pelvic floor muscle strength, quality of life, and global rate of change in postpartum women with stress urinary incontinence.

Objective

1. To analyze the effect of KE on PFMS by PFX 2 perineometer in postpartum women with SUI.

2. To analyze the effect of KE on quality of life (QoL), 1-h pad test values in postpartum women with stress urinary incontinence and global rate of change (GROC).

3. To analyze the effect of 90-90 BBE on PFMS by PFX 2 perineometer in postpartum women with SUI.

4. To analyze the effect of 90-90 BBE on quality of life and 1-h pad test values in postpartum women with stress urinary incontinence and GROC.

5. To analyze and compare the effectiveness of KE and 90-90 BBE on PFMS by PFX 2 perineometer in postpartum women with SUI.

6. To analyze and compare the effectiveness of KE and 90-90 BBE on QoL and 1-h pad test values in postpartum women with SUI and GROC.

Trial design

A single-center, parallel-group, randomized controlled superiority trial with two arms. The study is single-blinded, with the outcome assessor blinded.

Methods

Study setting

Department of Physiotherapy and Department of Gynecology and Obstetrics, Srinivas Medical College Hospital, Mangalore, India.

Participants: eligibility criteria

See Table 1.

Table 1.

Criteria of selection

Inclusion criteria	Exclusion criteria
1. Postpartum women with SUI who had spontaneous vaginal delivery with episiotomy. [30]	1. People with severe co-morbidities like hypertension induced by pregnancy. [34]
2. Age: 18-35 years, SUI symptoms at least once per week during postpartum period, 3-6 months after delivery. [30]	2. A history of chronic cough, constipation, pelvic surgery, spinal surgery, active urinary tract infection) diabetes mellitus. [30]
3. ICIQ-SF score more than 6. [31] UI while cough/sneeze, physical activity.	3. Women who had experienced UI before pregnancy, who had previous surgery for SUI, a neurologic or psychiatric disease, or a major medical condition, or those who were taking medications for SUI. [30]
4. 1 hr pad test score- mild to more severe - above 1 grams weight after 1 hr. [32, 33]	4. Postpartum women with SUI had history of kidney disease, or pelvic organ prolapse and pelvic surgery. [30]
	5. Cesarean section. [34]
	6. Postpartum women with urge UI and mixed UI.

Additional consent provisions for collection and use of participant data and biological specimens

Not applicable, the study does not use any biological specimens or provisions for additional data.

Explanation for the choice of comparators

The comparators used in the study were chosen based on the study design, research question, and to match the objectives of the study.

Control group (group A): Knack technique and Kegel’s exercises.

Experimental group (group B): Knack technique and 90-90 BBE exercises.

Interventions

Intervention of Knack technique for both the groups [18]:

Procedure:

1. High sitting without back support or stand straight with erect chest and pull inward the lower back.

2. Before cough, sneeze, or lift, contract the PFM and control the sphincters of urethra, vagina, and anus.

3. Perform effective inward lifting and squeezing of PFM.

4. Maintain the PFM contract as much as you can and do a minimally effective cough.

5. After the minimally effective cough, relax the PFM back to normal.

6. With increased forceful coughing, or 2 coughs in a continuation to maintain and control PF contraction.

Intervention for group A (APA—American Pregnancy Association Kegel’s exercise) [29]:

Procedure:

1. Locate the PFM by inserting a finger into the vagina and squeeze the surroundings or by controlling the urine flow during urination.

2. After locating the PFM, do 5–10-s contraction the PFM muscles, relax, repeat it for 10–20 times. Bladder should be empty while doing KE.

3. Concentrate only on PFM contraction.

4. Do not do this during urination that may weaken the PFM and increase the chance of urinary infection.

5. Once the subjects learn exercises, they will be asked to continue the interventions under supervision of clinical physiotherapist.

6. This should be done 10 repetitions, 3 sets a day, 3 days a week, for 8 weeks.

90-90 BBE: intervention for group B [27]:

Procedure (Fig. 1):

1. Subjects will be lying on stable floor; their feet will be placed on a wall and flexing their hips and knees at an angle of 90-90.

2. A 5-inch rubber ball will be placed between the knees. The inner aspect of the knees and thighs should feel the pressure. After that, lift both hips from the ground to do backward tilting of the pelvis. Balloon will be held in one hand; the other hand will be at 120 degrees of shoulder joint raise above head.

3. In this position, the subject should perform balloon blowing exercise, where the subjects should keep the balloon in one hand and do nose inspiration while resting the tongue on the roof of the mouth, then blow the air into the balloon for 5–8 s. A cycle of 75% of maximum inspiration for 3–4 s and expiration for 5–8 s should be followed with a pause of period of 2–3 s and repeat it for 4–5 times. This needs maintenance of IAP by allowing nose inspiration and not allowing the air going out from the balloon and mouth.

4. Subjects will be instructed not to keep so tight of the opening of the balloon for not allowing air in the balloon to reach the mouth cavity. Cheek muscles should not be used for balloon blowing. The physiotherapist will monitor the entire process.

5. All these interventions for the initial three sessions will be done under the guidance of physiotherapists in clinical or hospital set up, and then subsequent sessions will be done under supervision of physiotherapists at home (10 repetitions, 3 sessions a day, 3 days a week, for 8 weeks).

Fig. 1.

90-90 ball and balloon exercises performance

Comparisons:

• Group A: Knack + Kegel’s exercise

• Group B: Knack + 90-90 BBE

Strategy for treatment modification and adherence

Concomitant care

No participant will be restricted from receiving external care. If any participant in the intervention or control group is matching with the exercise program of the intervention group, the data would be excluded from statistical analysis.

Outcomes

Primary outcome measures:Pelvic floor muscle strength measured by PFX 2 perineometer (Fig. 2) [35–37]

Fig. 2.

PFX 2 perineometer

Secondary outcome measures:

• Quality of life and stress urinary incontinence functional independence measured by ICIQ-LUTSqol and (KHQ)-questionnaire (score: 19–76) respectively [38]

• The 1-h pad test [32, 33]

• Global rate of change (GROC) [39, 40]

Participant timeline

The CONSORT flow diagram depicts the participant timeline (Fig. 3).

Fig. 3.

CONSORT flow diagram depicts the participant timeline

Sample size

G*Power ver. 3.1.9.7 software through clincalc.com for Windows was used for sample size calculation. The calculation was based on pelvic floor muscle strength (PFMS), specifically the average pressure of maximum voluntary contraction (MVC) measured by the Peritron™ device. Reference values were obtained from a single-group pre–post quasi-experimental study by Cross et al., which examined the effectiveness of supervised Kegel’s exercise using biofeedback in women with stress urinary incontinence [29]. Values taken for sample size calculation are MVC pressure (average) mean ± SD in the supervised group; the mean ± SD of pre-intervention was 32.33 ± 17.32, and post-intervention was 43.63 ± 30.20, α value kept as 0.05 (95% CI), and β (power) value kept as 0.2 (80%) [29]. Total sample size: 74, control group: 37, experimental group: 37. Estimated dropout: 15%, final sample size including 15% dropout. Group A: 37 + 6 = 43, group B: 37 + 6 = 43. Final sample size (including dropout): 86.

Enrollment, intervention, and recruitment plan

The participants in the study would be recruited under the purposive sampling method. Participants will be recruited from referrals from obstetrics and gynecology physicians from Srinivas Hospital, Mangaluru, Karnataka, India. The study follows the Standard Protocol Items Recommendations for Interventional Trials (SPIRIT) guidelines (Fig. 4) [41]. The timeline for enrollment, intervention, and recruitment of participants has been illustrated using the CONSORT flow diagram [42].

Fig. 4.

CONSORT flow diagram for RCT/transparent reporting of trials

Allocation of participants and intervention: randomization and blinding

Participants would be allocated to two groups, randomized into an equal allocation ratio (1:1) using a block randomization method through a sealed envelope, with 43 randomized to intervention and 43 to control. Randomization for subject allocation would be double-blinded (both participant and researcher), facilitated by a person not involved in the study. Allocation of intervention will not be blinded and will be conducted by the researchers in the study (3 years of post-graduate experience in physiotherapy).

Block randomization: 22 blocks of 4 each would be used. Each block of 4 participants, allocated to two participants each to the control and experimental group from the first 21 blocks, and 1 each would be from the final 22nd block.

Data collection and follow-up

Data will be collected using the data collection sheet, which will focus on the demographics and primary outcome variables using reliable and valid tools. Primary outcome measure PFX 2 perineometer to measure PFMS and secondary outcome measures such as QoL, 1-h pad test, and GROC will be collected and recorded at pre-intervention, after 8 weeks, and follow-up at the 3rd month and 6th month by a blinded outcome assessor.

Data management: storage and confidentiality:

With the permission of the authors, data can be made available to the public.

The raw data would be systematically synthesized into an Excel sheet and stored in the institutional data repository system for further analysis for 3 years. The data would be managed both in soft and hard copies. Any personal information of the participants relating to direct identity would not be used for any purpose, and data confidentiality would be ensured by the investigators.

Plans for collection, laboratory evaluation, and storage of biological specimens for genetic or molecular analysis in this trial/future use

Not applicable. The study does not include the collection, evaluation, and storage of laboratory data through biological specimens for future use.

Data analysis

The data would be analyzed using the SPSS software package version 29. The normality of the data will be assessed using the Kolmogorov–Smirnov test. If the data are normally distributed, descriptive statistics will be expressed as mean ± standard deviation. For within-group analysis, paired t-tests will be applied to examine pre–post intervention changes. To compare changes in outcome measures across baseline, post-intervention, 3rd month, and 6th month follow-up, repeated measures analysis of variance (ANOVA) will be employed. Between-group comparisons at pre- and post-intervention will be performed using independent t-tests.

If the data are not normally distributed, descriptive statistics will be reported as median and interquartile range. Within-group differences will be analyzed using the Wilcoxon signed-rank test, while changes over time (baseline, post-intervention, 3rd month, and 6th month) will be examined using the Friedman test. Between-group comparisons will be conducted using the Mann–Whitney U test.

Effect size indices (ESI) will be calculated for both groups post-intervention. All analyses will be performed using IBM SPSS Statistics version 25.0 (Armonk, NY: IBM Corp.). A priori significance level will be set at P < 0.05 (95% CI). Type I error was fixed at less than 5%, following standard research methodology recommendations.

The primary analysis will compare between-group differences in pelvic floor muscle strength at post-intervention using intention-to-treat (ITT) analysis, which includes all randomized participants in their assigned groups, regardless of adherence. In addition, a per-protocol sensitivity analysis will be conducted, including only participants who complete at least 80% of the prescribed sessions.

Interim analyses

An interim analysis will be conducted after the post-intervention assessment to monitor data trends, adherence, and safety. This interim analysis will not be used for early stopping or formal efficacy testing but solely to evaluate feasibility and data integrity.

Additional analyses

Subgroup analyses will be performed based on demographic variables and baseline clinical characteristics.

Handling of non-adherence and missing data

ITT analysis will be applied, including all participants according to their original group allocation. Missing outcome data will be addressed using multiple imputation under the assumption that data are missing at random. Additionally, sensitivity analyses will be performed using the last observation carried forward (LOCF) method to assess the robustness of findings under different assumptions about missingness.

Plans to give access to the full protocol, participant-level data, and statistical code

The protocol would be published, and the dataset would be provided in the repository for public access after completion of the study.

Oversight and data monitoring

The data would be monitored monthly by the institutional research committee comprised senior researchers from the study (PK and SR) along with the head of the department and head of the institution. Any administrative and organizational support would be provided by the institution where the study will be conducted.

Adverse event reporting and post-trial care

If any adverse effects are noted, they would be immediately reported by the supervising investigators with record maintenance. If required, participants would be given appropriate treatment and post-trial care against any harms at the institutional hospital.

Frequency and plans for auditing trial conduct

Not applicable.

Protocol amendment reporting

Any essential changes in the protocol would be intimated to the ethical committee, and consequent changes would be made in the ethical approval letter along with the participant information sheet.

Dissemination plans

The findings of the study would be published in quality, peer-reviewed, high-impact factor indexed journals. Also, the findings would be presented at national and international conferences related to breast cancer.

Discussion

This RCT protocol explores a novel, feasible approach to pelvic floor muscle (PFM) strengthening by indirectly activating the abdominal muscles and diaphragm, which work synergistically with the pelvic floor to regulate intra-abdominal pressure (IAP). The 90-90 ball and balloon exercise (BBE) integrates respiratory and postural mechanisms, enhancing neuromuscular control of the pelvic diaphragm. Prior evidence supports its effectiveness in improving stability and respiratory function in low back pain [27], and its physiological basis suggests potential benefits for reducing SUI by promoting coordinated co-contraction of abdominal, diaphragmatic, and pelvic floor muscles [28]. Compared to Kegel’s exercise (KE), which is often limited by difficulties in correct performance and lack of diaphragmatic engagement, the 90-90 BBE may provide a more accessible and comprehensive strategy for postpartum women. If effective, it could offer an alternative means of improving pelvic floor muscle strength (PFMS) and quality of life in this population.

Practical and operational considerations

Conducting this trial among postpartum women involves several operational challenges. Recruitment is dependent on referrals from obstetricians and gynecologists, and many women may be hesitant to report or discuss urinary incontinence due to cultural sensitivities. To overcome this, we have included education and counseling sessions to improve awareness and willingness to participate. Adherence is another important factor, particularly with Kegel’s exercises, which are often difficult for women to learn and sustain. Therefore, supervised sessions and periodic monitoring by physiotherapists are incorporated to encourage compliance. For the experimental group, training women to perform the 90-90 BBE correctly requires additional time and demonstration, but early clinical experience suggests that it may be easier for women to perceive compared with isolating pelvic floor contractions.

Limitations

Several limitations should be acknowledged. First, the sample size estimation was derived from a pre–post single-arm study, which may overestimate the true between-group effect size due to natural history, regression to the mean, and confounding factors. Second, as the study is conducted at a single center, the generalizability of findings may be limited to similar hospital-based postpartum populations in India. Third, although the outcome assessor is blinded, participants cannot be blinded due to the nature of the interventions, which may introduce performance bias. Fourth, interim analyses are planned for monitoring feasibility and safety; however, this may marginally increase the risk of type I error, and results should be interpreted with caution. Finally, missing data will be addressed using multiple imputation, but this approach assumes data are missing at random, which may not always hold true.

Trial status—protocol version 1

Trial registered in CTRI—18.06.2024.

First enrollment of participants—15.07.2024.

Proposed period of enrollment—15.07.2024 to 15.07.2025.

Intervention period—15.07.2024 to 30.10.2025.

Follow-up period—30.10.2026 to 30.04.2026.

Final analysis and submission: 30.05.2026.

Abbreviations

SUI

Stress urinary incontinence

KE

Kegel’s exercise

KT

Knack technique

90-90 BBE

90-90 Ball and balloon exercise

PFM

Pelvic floor muscle

PFMS

Pelvic floor muscle strength

APA

American Pregnancy Association

QoL

Quality of life

GROC

Global rate of change

MVC

Maximum voluntary control

IAP

Intra-abdominal pressure

RCT

Randomized clinical trial

CTRI

Clinical Trial Registry of India

ICMR

Indian Council of Medical Research

ESI

Effect size index

CI

Confidence interval

SD

Standard deviation

ANOVA

Analysis of variance

Authors’ contributions

RS.: protocol/project development, study design, drafting, and reviewing of the manuscript. KS.: primary investigator, protocol/project development and manuscript writing/editing. PM.: protocol/project development, manuscript writing and editing. PK: manuscript writing/editing. All the authors have read and approved the final manuscript.

Funding

None.

Data availability

With permission from authors.

Declarations

Ethics approval and consent to participate

Ethical issues: no ethical issues based on the Declaration of Helsinki 2013. Ethical approval: Srinivas University Ethical Committee—Ref. No: 25/Ahs/2024. Written informed consent was taken from participants.

Consent for publication

Yes, from all authors.

Competing interests

None from any of the authors.