This single-blinded randomized controlled study was carried out in compliance with the ethical principles of the 1975 Helsinki Declaration. It took place from October 2022 to December 2023. Our study was registered retrospectively with Clinicaltrials.gov under the identifier NCT06207721 on 5 January 2024.

Before conducting the study, the Faculty of Medicine, Al-Azhar University, Damietta, ethics committee board accepted our procedures (number, DFM-IRB000012367-24-03-024). All participants signed a consent form after hearing an explanation of the procedure. They are aware that they can withdraw their consent and quit taking part in the study at any time without harming the researchers.

Four hundred children diagnosed with functional constipation were randomly selected to participate in the study. All subjects were recruited from general practitioner and pediatric outpatient clinic in general and central hospitals in Damietta governorate, Egypt. They were selected according to the subsequent criteria: The participants ranged in age from 4 to 18 years old, from both sex, diagnosed to have FC according to Rome criteria III (appendix I) [3, 5]. They had normal or healthy weight according to Centers for Disease Control and Prevention (CDC) growth charts for girls which ranged from body mass index (BMI) for age 85th to 95th percentiles [25].

Children with severe delay in motor skills development, constipation caused by medicine, bowel surgery (except appendectomy), endocrine and metabolic disorders (diabetes mellitus, hypercalcemia, hypothyroidism, and diabetes insipidus), psychiatric and neurological disorders (cerebral palsy, spina bifida, PDD-NOS, autism, or anorexia nervosa), Hirschsprung’s disease, or Down syndrome were excluded from this study.

Four hundred and twenty-five children diagnosed with functional constipation were assessed for suitability; due to their failure to fulfil the inclusive criteria, 20 participants were eliminated from the experiment, and five parents refused their children to join. As a result, 400 children diagnosed with FC were involved in this experimental. Random allocation software was used to split them into two equal-sized groups at random in order to minimize selection bias [26]. The outcome assessor was blind to recruitment, randomization, and allocation of subjects.

The children were sorted into two equal groups at random through the GraphPad QuickCalcs website [27] (n = 200 in each group): group A (control group), which treated with pharmaceutical treatment (including diet regimen, and laxatives as polyethylene glycol (PEG) syrup (0.7 g/kg daily); and group B (intervention group), which treated with the same pharmaceutical treatment conducted to group A in adding to TRP. A depiction of participant retention and randomization during the study is presented in Fig. 1.

All participants were examined at the start of the treatment and again 6 months later. They were assessed for the following outcomes:

The primary outcome: Rome III Diagnostic Questionnaire for the Pediatric Functional Gastrointestinal Disorders (appendix I) [3, 5]

It was used as an indicator for the treatment success which is defined according to the Rome III criteria as higher improvement of FC symptoms with less or no laxative use.

The SF-36 scale for evaluating the QL was determined to be credible and accurate and thought to be acceptable for Arab populations, particularly in North Africa, after having been adapted and altered in Tunisia and utilized in research on Tunisian participants [28]. The Arabic version proved to be an objective, simple, and legitimate instrument for measuring the health-associated QL in the general population as a whole [29].

The Arabic-translated short form 36 questionnaire is a widely used self-administered measure for evaluating the QL. It has 36 questions. The results are converted into a scale of 0 to 100, with higher values indicating better QL. The questionnaire was divided into eight domains: physical functioning, general health, bodily pain, role functioning, social functioning, role emotional, mental health, and vitality. Our team contacted general practitioner or pediatrician outpatients’ clinics in general and central hospitals in Damietta governorate to explain the objectives of the study. Letters revealing the goals of the research were given to the families, which included an interview during which two members of the team responded to the queries of the parent(s)/guardian(s). If the invitation to join the research was accepted, a written agreement was agreed upon, then the questionnaire forms were filled at the start of the study and after 6 months of follow-up by participant children aging 12 years and more, and by parents of participant children aging below 12 years, in both situations the questionnaire forms were submitted under the guidance of a member of the team with the utmost level of privacy [29].

Two groups received the following treatment: group A (control group), which received pharmaceutical treatment (including diet regimen, and laxatives as polyethylene glycol (PEG) syrup (0.7 g/kg daily); and group B (intervention group), which received the same pharmaceutical treatment conducted to group A in addition to TRP. Our team contacted general practitioners or pediatrician outpatients’ clinics in general and central hospitals in Damietta governorate to monitor with the children’s families the diet regimen, the dose of laxatives, and any adverse effects of laxatives, e.g., abdominal pain, vomiting, nausea, and abnormalities [30].

The telerehabilitation home program was conducted at home by parent(s)/guardian(s) who were trained and supervised by a physiotherapist. The telerehabilitation home program included the following: (i) isometric training of the abdominal muscles, (ii) breathing exercises, and (iii) abdominal massage.

The target of isometric training of the abdominal muscles is to rise intra-abdominal pressure (that compresses the bowels) and the propulsive force of the colon throughout intentional power [31, 32]. Bearing in mind the secondary synergic stimulation stuck between the muscles of pelvic floor and the muscles of lower abdomen, intentional isometric contraction of upper abdomen with coincident relaxation of lower abdomen increases coordination of muscles and relaxation of the external anal sphincter and pelvic floor, so improving defecation [31, 33, 34]. The exercises were performed in while the participant was either in the position of lying down in left lateral decubitus position with flexed knee and hip at right angle or in the position of sitting. In the first position, the exercise is initiated with two sequences of 8 contractions and relaxations for 3 months, then upgraded to two sequences of 12 contractions and relaxations for the following 3 months. In the second position (sitting), the exercise is initiated with one sequence of 3 contractions and relaxations taking 10 s for 3 months then upgraded to five sequences for the following 3 months. Success of the exercise is considered when the lower abdominal protrusion is obvious, which represents the concurrent relaxation of lower abdomen and pelvic floor, and the series starts from this point [34]. The goal of breathing exercises is to reach a steady form of abdominal breathing, fortify the muscles of abdomen, and increase harmonization between breathing, contraction of abdominal and anal muscles, and propulsions of colon. Standard diaphragmatic breathing was attained via an adjusted exercise while with the participant in the sit down position, one hand is located over the abdomen, and the other hand over the thorax; the participant is ordered to breathe in little by little, profoundly and increasingly for 6 to 8 s, with air retention for 10 s and thin breathe out slowly for 6 to 8 s. Two sequences of ten repetitions are accomplished. Success of the exercise is considered when superior motion of the hand placed over the abdomen is reached in comparison with less or no movement of the hand over the thorax, and the series starts from this point [35]. The goal of abdominal massage is to achieve propulsive massage of the abdomen to enhance motility of colon and rectum to improve intestinal functions and defecation [14, 36, 37]. Sluggish rounded clockwise movements are done, along the contour of the colon, with continuous adequate pressure on the abdomen using a steady tennis ball on every point for 1 min, starting by the ascending colon and moving on the way to the sigmoid colon.

No noticeable detrimental effects were seen while the treatments were in use. Each participant was asked to explain any concerns they were experiencing.

The sample size was estimated using the OpenEpi I program with a 95% confidence level and 80% power. We intended to have the ability to find a variance of no less than 15% in the result between the two groups; thus, we required a minimum of 200 participants in each group.

Data from history, clinical examination, laboratory tests, and outcome measures were input and analyzed using Microsoft Excel. Data was inputted into the computer and analyzed with IBM SPSS software version 26 (Armonk, NY, IBM Corp). The qualitative findings have been explained using numbers and percentages. The normality of the distribution was verified using the Shapiro-Wilk test. The Student T test was performed to determine the statistically significant value of the variance between two study groups’ averages. The Mann-Whitney U test is a nonparametric test that allows two groups or conditions or treatments to be compared without making an assumption that values are normally distributed. The chi-square test was used to examine the relationship between two or more qualitative variables. The Monte Carlo test was used to investigate the association between two groups with qualitative factors when the predicted count exceeds 5 in more than 20% of cells. Results were classified as non-significant (P > 0.05), significant (P < 0.05), or highly significant (P < 0.001). The data related with the study are not publicly available; however, they are available from the corresponding author upon reasonable request.