The effect of eight weeks of Kegel exercises combined with vitamin D3 and magnesium supplementation on lumbar stabilizer muscle thickness and urinary incontinence severity in postmenopausal women

The study aims to evaluate the effect of 8 weeks of Kegel exercises combined with vitamin D3 and magnesium supplementation on lumbar muscle thickness and urinary incontinence severity in postmenopausal women.

A randomized, parallel-group, assessor-blinded clinical trial to assess the impact of Kegel exercises combined with supplements on lumbar muscle thickness and urinary incontinence severity. Participants will be randomized 1:1 into intervention and control groups.

This randomized, assessor‑blinded, parallel‑group clinical trial will be conducted in 2025 at a private physiotherapy clinic in Isfahan

Inclusion criteria were postmenopausal women aged 60–65 years with urinary incontinence who had not participated in regular exercise programs or used vitamin D or magnesium supplements during the past three months and had no history of pelvic or lumbar spine surgery or severe chronic diseases limiting physical activity. Exclusion criteria included unwillingness to participate, conditions or injuries limiting exercise performance, use of medications affecting muscle or urinary function, recent regular use of vitamin D or magnesium supplements, and any medical contraindication to participation. Detailed criteria are presented in the relevant section.

Participants will be randomly assigned to two groups. The intervention group will perform Kegel exercises for 8 weeks (3 sessions/week, 3 sets of 10 repetitions with 8‑second contractions) and receive daily vitamin D3 (2000 IU) and magnesium (200 mg). The control group will receive placebo capsules without exercise.

Primary outcomes include transversus abdominis and multifidus muscle thickness and urinary incontinence severity.

After obtaining written informed consent, eligible participants were enrolled in the study. To generate the random allocation sequence, a block randomization method with a fixed block size of 4 was used to ensure balance in the number of participants between the intervention and control groups throughout the recruitment process. The random sequence was generated using the statistical software SPSS version 26 (IBM Corp., Armonk, NY, USA). Specifically, all possible allocation permutations within a four-person block were first defined, including six possible arrangements (AABB, ABAB, ABBA, BAAB, BABA, BBAA), where A represented the intervention group and B represented the control group. Subsequently, a uniform random number was generated for each block using the function RV.UNIFORM(0,1), with the random number generator seed set to 2024 to ensure reproducibility. Based on these random numbers, one of the six possible block arrangements was randomly selected for each block. The blocks were then concatenated sequentially to form the final allocation list. Accordingly, every four consecutive participants were assigned to the intervention and control groups according to the predefined block structure, maintaining a 1:1 allocation ratio within each block. To ensure allocation concealment, the final sequence was encoded and placed into sequentially numbered, opaque, sealed envelopes (SNOSE). The envelopes remained sealed until the moment of participant enrollment and were opened sequentially only after each participant had been formally enrolled in the study. All procedures, including random sequence generation, block selection, seed setting, and envelope preparation, were performed by an independent researcher who had no involvement in participant recruitment, intervention implementation, or outcome assessment, thereby minimizing the risk of selection bias.

In this trial, participants will not be blinded to the intervention they receive; however, the outcome assessor will be blinded to group allocation. The assessor responsible for measuring muscle thickness, pelvic floor strength and endurance, and urinary incontinence scores will have no access to the allocation list, and group information will be kept confidential. Additionally, the statistical analyst will receive coded data (Group A and Group B) to ensure blinded data analysis.

Due to the need to protect participant confidentiality and prevent disclosure of individual-level data, there is no plan to share Individual Participant Data (IPD). Only aggregated results will be reported in scientific publications.

Full protocol of the randomized controlled trial including study design, Kegel exercise intervention protocol, vitamin D3 and magnesium supplementation protocol, inclusion and exclusion criteria, measurement procedures including ultrasound assessment of transversus abdominis and multifidus muscles, urinary incontinence assessment using the ICIQ‑SF questionnaire, biochemical measurements, and statistical analysis plan.

The study protocol will become available after completion of the study and publication of the results and will remain accessible for up to 5 years after publication.

Academic researchers, journal reviewers, and researchers who submit a scientifically justified request.

The document will be available solely for research, educational, or peer‑review purposes. Its use must comply with research ethics principles and protection of participant confidentiality.

Requests should be sent by email to the responsible investigator.

Requests will be reviewed via email. If approved, an electronic copy of the study protocol will be provided. No identifiable participant information will be shared.