A three-arm parallel-group randomized controlled trial was conducted with 90 women aged 23-42 years, 6-8 weeks postpartum. Participants were randomly assigned to one of three groups: no kinesiotaping (control), placebo kinesiotaping (no tension), and kinesiotaping with 50% tension. All participants followed the same exercise program. The primary outcome measure was the Diastasis Recti Index (DRI), assessed via ultrasound at baseline, 4 weeks, and 8 weeks.

This was a three-arm, parallel-group, randomised controlled trial with concealed allocation. The allocation of subjects to the experiment was arranged chronologically. Each woman meeting the inclusion criteria was consecutively qualified. None of the participants were aware of group allocations or the interventions used in each group according to CONSORT's diagram. Each subject was given the same exercises (instructor-led) and tested individually to maintain study blinding.

The clinical rationale for reducing DRA using Kinesio taping was evaluated in 90 females in the late postpartum period, defined as 6 - 8 weeks after childbirth.

The eligibility criteria for the study were:

• aged between 25 and 45 years
• first singleton pregnancy
• natural childbirth
• no medical contraindications for exercising and taping.

The exclusion criteria were:

• childbirth through cesarean section
• more than eight weeks from natural childbirth
• body mass index (BMI) over 35 kg/m2

All study participants were randomly divided into three groups of 30:

• Group 1 - no taping - control group,
• Group 2 - taping without tension - placebo group,
• Group 3 - taping at 50 % tension - tape group. There were no statistically significant differences in body dimensions between the study groups. All participants followed the same exercise program designed for postpartum females (Additional material - presentation of the exercise program). A Tanita electronic scale measured body weight and height. Examinations were conducted once per session at the beginning of the project and in the 4th and 8th weeks of training. Ultrasound examination used the Mindray DP10 apparatus (38 mm linear transducer) at a frequency of 5.0, 7.5, and 10.0 MHz and was performed by an ultrasound-trained physiotherapist. Two points were marked in a straight line with the cursor, the right and the left medial edge of the rectus muscle, and the inter-rectus distance was measured with an accuracy of 0.2 cm. Measurements were recorded at the navel line, 4.5 cm above, and 4.5 cm under the navel. Also, waist circumference measurement used a tailor's tape (with 0.2 cm accuracy), which was measured midway between the edge of the tenth rib and the highest point of the iliac crest. Inter-rectus distance and waist circumference were measured by the same person (the first author of the paper) over three project sessions. The DRA width at the given measurement line was normalized by waist circumference taken during the same measurement, which allowed the DRA width to be independently comparable to each subject's body dimensions.

This training and research project was conducted over eight weeks and started 6 - 8 weeks after natural childbirth. All study participants were included in the exercise program designed for postpartum females. Exercises included four sets that changed every two weeks and were held individually with a physiotherapist three times a week, every two to three days, for 45 minutes each unit. All participants performed breathing exercises, body posture correction, abdominal muscle strengthening exercises (transverse, oblique, and rectus abdominis muscles), and engaged other muscles to improve overall physical fitness.

The Kinesiology Tape used in this study has a European quality certificate (CE). Before the exercise program, on the day of the first ultrasound, participants had tapes placed on their abdomens. The tape length for each participant was 20 cm to ensure the ends were located on the lateral edges of the rectus abdominis muscles. Both ends of the tape were simultaneously attached to the abdomen, with two attached from the navel line upwards and one below it.

Each participant in the tape group was asked to breathe in using the abdominal muscles, and after a maximal stretch of the abdominal integuments, three tapes were attached at 50% tension or without tension. The detailed procedure for applying Kinesiology tape is described in Additional material. The taping procedure was repeated once per week, with the tapes attached for six days and removed at the end of the 6th day. The placebo and tape groups had a break on the 7th day, and the scheme was repeated for 8 weeks. After 4 weeks, a second ultrasound similar to the first measurement of the rectus abdominis muscle was performed as before. The 3rd measurement was taken after completing the exercise program, which took 8 weeks. Primary outcome: Diastasis Recti Index (DRI) was computed in order to normalize the ultrasound examination results. The DRA width was divided by waist circumference and multiplied by 100% to determine the changes in diastasis width at the navel line (DRIn), above the navel (DRIan), and under the navel (DRIun): DRI [%]=DRAw[cm]/(waist circumference [cm] )*100% where

• DRAw is the diastasis recti abdominis width at a given measurement line: at the navel, above the navel, and under the navel (respectively)
• waist circumference was measured at the navel line in a given session. The DRI index expressed as a percentage of waist circumference makes it possible to compare diastasis width changes dependently of body size. A zero DRI value does not mean that the linea alba is zero width. Normal linea alba at the navel line is approximately 2.24 cm ± 0.8 cm. A higher DRI points to a worse therapy outcome, and a DRI decrease indicates an improved result. The best result of DRI = 0 represents normal linea alba width and no DRA.

The effectiveness of Kinesio taping was assessed based on intergroup differences in the initial

measurement values (DRI1) taken before the start of the project, the second measurement after 4 weeks (DRI2), and the third measurement after 8 weeks (DRI3). The intergroup analysis compared the measurements taken at the navel line, above the navel, and under the navel. Determining the significance of intergroup differences between the three subsequent DRI scores will make it possible to determine the optimal therapy duration for obtaining the desired effects. Meanwhile, intragroup changes in the DRI reflect the effect of a given treatment, including exercise alone, exercise in combination with taping without tension, and exercise with taping at 50% tension.

Inclusion Criteria:

• - aged between 25 and 45 years
• first singleton pregnancy
• natural childbirth
• no medical contraindications for exercising and taping.

Exclusion Criteria:

• - childbirth through cesarean section
• more than eight weeks from natural childbirth
• body mass index (BMI) over 35 kg/m2

The eligibility criteria for the study were:

• aged between 25 and 45 years
• first singleton pregnancy
• natural childbirth
• no medical contraindications for exercising and taping.

The exclusion criteria were:

• childbirth through cesarean section
• more than eight weeks from natural childbirth
• body mass index (BMI) over 35 kg/m2

IPD will not be shared due to the lack of participant consent for data sharing and protect privacy in accordance with data protection regulations.

None of the participants were aware of group allocations or the interventions used in each group according to CONSORT's diagram. Each subject was given the same exercises (instructor-led) and tested individually to maintain study blinding.