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Efficacy of a Core Strengthening Program for Diastasis Rectus Abdominis in Postpartum Women: A Prospective Observational Study

Leopold, Madeline BA1; Santiago, Kristen BA1; Cheng, Jennifer PhD1; Keller, Leah CPT2; Abutalib, Zafir MHS3; Bonder, Jaclyn MD4; Sharma, Geeta MD5; Tenforde, Adam MD6,7; Casey, Ellen MD1

Author Information
Journal of Women's Health Physical Therapy: October/December 2021 - Volume 45 - Issue 4 - p 147-163
doi: 10.1097/JWH.0000000000000214

Abstract

INTRODUCTION

Diastasis rectus abdominis (DRA) is the relative displacement of the rectus abdominis muscles due to a widening of fascial connection that commonly occurs during pregnancy.1 Up to 60% of postpartum women have DRA,2 and unfortunately for many, it does not resolve naturally.1 DRA is caused by stretching and thinning of the linea alba and is characterized by an increased interrectus distance (IRD). The normal IRD in nulliparous females has been shown to be 0.75 ± 0.43 cm above the umbilicus at rest; in comparison, the IRD in males is higher and averages 1.62 ± 1.04 cm.3 It is important to note that these averages may not represent optimal IRD, as the standard deviations (SDs) are not minimal. The IRD threshold to diagnose DRA varies across studies and has been defined as values exceeding 1.5,4 2.0,5 2.2,6 or 2.5 cm.7 A recent study by Mota et al8 reported IRD values of 1.7 to 2.8 cm at the 50th percentile, and 2.8 cm and 3.0 cm represented the 80th and 90th percentile values, respectively. Furthermore, IRD can vary based on length of time from delivery, with average IRDs of 2.68 cm at 6 to 8 weeks, 2.38 cm at 12 to 14 weeks, and 2.24 cm at 24 to 26 weeks postpartum.8 A schematic of abdominal musculature with and without DRA is shown in Figure 1.

F1
Figure 1.:
Schematic of the abdominal musculature. Illustrations represent abdominal musculature (A) without diastasis; (B) with open diastasis; (C) with open diastasis below the umbilicus; and (D) with open diastasis above the umbilicus.

The significant stretching of the linea alba disrupts the structural connectivity of the abdominal muscles,4 which can affect core stability by compromising the capacity of the abdominal muscles to generate force.5 These morphological changes of the abdominal muscles are proposed risk factors for postpartum low back pain (LBP), stress urinary incontinence (SUI), pelvic pain and instability, and cosmetic concerns.9,10 To alleviate these issues, women are encouraged to perform strengthening exercises that target the abdominal muscles to reduce their DRA.11

Core strengthening is thought to decrease DRA by causing greater contraction of the abdominal muscles, producing a stronger horizontal force that pulls the muscles together.12–14 Although several studies have shown that core strengthening improves DRA, there is no widely accepted exercise program directed at correcting this issue. Most of the exercise programs involved in these studies were hands-on and conducted in person; therefore, they may not be accessible to the general population. Furthermore, some studies used palpation or calipers to diagnose DRA, and only a few studies used ultrasound to measure IRD.13–16 Compared to palpation, musculoskeletal ultrasound has been shown to be the most valid and reliable measure of IRD and is able to detect small changes better than other methods.17–21 It is important to note that the validity and reliability of musculoskeletal ultrasound in measuring the IRD has been well established above or at the level of the umbilicus, but validity and reliability of IRD measurement below the umbilicus has yet to be established.22,23

The primary aim of this study was to assess changes in IRD following participation in a 12-week home exercise core strengthening program in postpartum women with DRA. The secondary aim was to investigate whether the core strengthening program affects symptoms that may be related to DRA, including LBP-related disability, SUI, pelvic floor dysfunction, and body image.

METHODS

Ethics

This prospective observational study was approved by the Institutional Review Board and was conducted in accordance with the Declaration of Helsinki. Written informed consent was obtained from all participants prior to any research activities.

Participant Recruitment

Participants were recruited through advertisements and flyers geared toward postpartum women. Advertisements and flyers were posted online on social media and local moms' groups, and information about the study was also distributed by word of mouth. Inclusion criteria required that participants be healthy women between the ages of 18 and 45 years who were not currently pregnant, were 12 weeks to 36 months postpartum, and had DRA with an IRD of at least 2.0 cm diagnosed using musculoskeletal ultrasound. Exclusion criteria included a history of ventral/umbilical hernia prior to pregnancy, current pregnancy, more than 36 months postpartum, a Beighton score (used to quantify joint laxity and mobility)24 greater than 5/9, inability to participate in a regular online core strengthening program, and inability to attend onsite data collection sessions at Hospital for Special Surgery. IRDs of at least 2.0 cm were confirmed with musculoskeletal ultrasound prior to enrollment of each participant.

Ultrasound Measurements

A single investigator performed all ultrasound screenings and measurements using a SonoSite X-Porte musculoskeletal ultrasound machine (Sonosite, Bothell, Washington). This investigator had 1 year of experience in performing IRD measurements and was trained by a fellowship-trained sports medicine physician with over 10 years of experience in musculoskeletal ultrasound. The measurements were performed in person in an outpatient office. IRD was measured at 3 cm above and below the umbilicus. Measurement sites were marked using a surgical skin marker. At each site, IRD was measured after a deep breath both at rest and during a head raise, which is thought to recruit the contraction of the rectus abdominus muscles.25 Each participant's head height on the table was measured using a Charder HM200P PortStad Portable Stadiometer (Charder, Taiwan). The top platform of the stadiometer was then raised 2 cm above each participant's measured head height. Participants were asked to lift their heads until their foreheads lightly tapped the top platform of the stadiometer. This method ensured that all participants lifted their heads the same amount. Two centimeters was chosen as the distance for the head raise, as it allowed for partial scapular clearance, clear contraction of both rectus abdominis, and easy visualization of the IRD under ultrasound (Figure 2). Three trials were collected at each location for both resting and contracted states. Representative ultrasound images are shown in Figure 3. IRD measurements were collected at baseline and 12 weeks. Participants were included in the study if their IRD at rest, either above or below the umbilicus, was 2.0 cm or more. This cut-off for DRA was chosen based on ranges of IRD musculoskeletal ultrasound measurements in nulliparous women (1.0 cm above and 1.5 cm below the umbilicus26 vs 2.2 cm above and 0.09 cm below6) and parous women (2.03 cm ± 1.05 above the umbilicus3). The minimum clinically important difference of IRD has been reported as 0.41.23

F2
Figure 2.:
Images showing 2-cm head lifts and placement of the stadiometer.
F3
Figure 3.:
Interrectus distance (IRD) measured using SonoSite X-Porte Ultrasound in both resting and contracted states at 2 locations along the linea alba. (A) IRD at rest 3 cm above the umbilicus; (B) IRD during contraction 3 cm above the umbilicus; (C) IRD at rest 3 cm below the umbilicus; and (D) IRD during contraction 3 cm below the umbilicus.

Intraclass correlation coefficients (ICCs) were calculated to measure the reliability of measuring IRD via ultrasound. Reliability classifications were based on the following guidelines developed by Cicchetti et al27: poor: <0.40; fair: 0.40 to 0.59; good: 0.60 to 0.74, and excellent: 0.75 to 1.00. A pilot study showed good intrarater reliability, with ICCs of 0.754 above the umbilicus and 0.740 below the umbilicus.

Questionnaires

At the baseline appointment, each participant was asked to fill out a form containing demographics and medical history pertaining to their most recent pregnancy, the International Consultation of Incontinence-Urinary Incontinence Short Form (ICIQ-UI) to assess SUI,28 the Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Questionnaire (PISQ-12) to assess pelvic floor function,29 the Body Shape Questionnaire (BSQ) to assess body image,30 and the Quebec Back Pain Disability Scale (QBPDS) to assess LBP-related functional disability.31 The ICIQ-UI score ranges from 0 to 21, with a higher score indicating greater symptom severity, and has shown validity and reliability for measuring urinary incontinence in pregnant and postpartum women.32 The PISQ-12 score ranges from 0 to 48, with a lower score indicating greater impairment, and has shown both reliability and validity.29 The BSQ score ranges from 16 to 96, with a higher score indicating more body shape concern, and has shown good test-retest reliability33; it has also been used to assess body image in postpartum women.34 The QBPDS score ranges from 0 to 100, with a higher score indicating more LBP-related disability, and has a test-retest reliability of 0.92.31 It has been used to assess pelvic girdle pain in postpartum women.35 All questionnaires were administered at 12 weeks (during week 12 of the core strengthening program). Women who participated in the additional maintenance phase were also asked to complete the questionnaires at 24 weeks. At the end of the study, participants were asked to rate their satisfaction with the 12-week core strengthening program on a scale of 0 to 10, with 10 being the most satisfied, and to indicate whether they would recommend the program to a friend.

Intervention

The online, video-based core strengthening program was based on a previously reported exercise regimen for DRA36 and involved: (1) daily transversus abdominis activation with coordinated breathing and pelvic floor muscle engagement (10 minutes per day); (2) coaching on alignment, posture, and proper core engagement while performing daily activities; (3) education on how to optimally engage the core muscles during exercise; and (4) specific low-impact weekly workouts employing aerobic and resistance exercises to target muscle imbalances associated with DRA and to stimulate automatic core engagement during multijoint, compound movements (up to 4 times for <30 minutes per week). Program details are shown in Table 1 and are highlighted in the Supplementary Video, available at: https://links.lww.com/JWHPT/A48. Each low-impact workout began with a warm-up and concluded with a gentle stretch. Participants were taught to perform isometric contractions of the transversus abdominis in multiple body positions, such as seated upright and lying supine, during which the spine remained neutral (ie, no flexion or extension). Participants were encouraged to simultaneously lift the pelvic floor musculature while performing the transversus abdominis contractions. Common forward-flexion exercises (ie, sit-ups, crunches, and crossover crunches) were excluded. Participants were also asked to forego all exercises outside of those specified in the core strengthening program during the exercise intervention until the final clinical measurements were collected. Exercises that participants were asked to abstain from included other forms of core training, yoga, Pilates, strength/resistance workouts, and high-intensity training. The core strengthening program aligned with the latest postpartum practice recommendations for DRA that were published in a Delphi consensus study.37 Participants were provided with the equipment needed for all exercises in the program, which included a resistance band and 2 sets of hand weights. Coaching and guided instructions for all exercises, workouts, and educational information were communicated through a series of premade videos that participants accessed through an app subscription available on their phones, computers, and mobile devices. The app provided a detailed schedule of the 12-week program, including guided exercises and workouts, education, instructional videos, and reminders. The program and app subscription were provided to each participant for free for the duration of the study.

Table 1. - Online Core Strengthening Program Details
The 12-wk program is composed of core strengthening, supplementary workouts, and education.
I. Core strengthening is the primary focus of the program and is referred to as “core compressions.” Core compressions are defined as exercises involving the a bdominal draw in maneuver with coactivation of the transversus abdominis (TrA), diaphragm, and pelvic floor musculature. The core compressions are performed in various positions and timed with exhaling. Video coaching includes reminders to coordinate muscle contraction with breathing. Emphasis is placed on the consistent performance of these core compressions on a daily basis.
II. The supplementary workouts are composed of strengthening, stretching, and aerobic exercises. Strengthening exercises incorporate body weight, resistance bands, and hand weights. Coaching during the supplementary workouts prioritizes coordination of the deep core musculature engagement with exhalation during the exertion phase of each movement. There is a gradual progression to multiplanar, functional exercises over the 12 weeks.
III. Education is a primary focus of the first week, but reminders are woven into each session. Towards the end of the program, education about how to safely return to exercise outside the program is provided.
Week Education Day Primary Workouts: Core Training Supplementary Workouts
1 Introduction to TrA muscle activation and abdominal draw in maneuver with cocontraction of the diaphragm and pelvic floor musculature.
Education about core engagement in posture, breathing, alignment, functional movement.
Tips to incorporate core strengthening/stability into daily activities are discussed.
Participants are instructed to coordinate TrA contraction with engagement of pelvic floor musculature and exhalation during strength training exercises.
1 5 min of “core compressions” performed in various positions (2 min in quadruped, 2 min seated upright against a wall, 1 min in a standing incline plank with hands against the wall). 20-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2 6 min of “core compressions” performed in various body positions (2 min in quadruped, 2 min seated upright against a wall, 2 min in a wall-sit with neutral spine). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature.
3 7 min of “core compressions” performed in various body positions (2 min in quadruped, 1 min in standing incline plank with hands against the wall, 2 min in fetal position on the right side, 2 min in fetal position on the left side). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. 22-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4 7 min of “core compressions” performed in various body positions (2 min in quadruped, 2 min in seated upright, 1 min in standing incline plank, 2 min in wall-sit). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature.
5 8 min of “core compressions” performed in various body positions (2 min in quadruped, 2 min seated upright, 2 min in fetal position on the right side, 2 min in fetal position on the left side). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. 29-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6 9 min of “core compressions” performed in various body positions (2 min in quadruped, 1 min in standing incline plank, 2 min in fetal position on the right side, 2 min in fetal position on the left side, 2 min in supine with knees bent). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. 13-min restorative workout that includes low-impact aerobic exercises, dynamic stretches, and light resistance exercises.
7 10 min of “core compressions” performed in various body positions (2 min in quadruped, 1 min in standing incline plank, 2 min in wall-sit, 1 min in standing incline plank [second set], 2 min in supine with knees bent, 2 min in quadruped [second set]). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature.
2 1 10 min of “core compressions” performed in various body positions (2 min in quadruped, 2 min seated upright, 2 min supine knees bent, 2 min supine spinal twist with knees to the right, 2 min supine spinal twist with knees to the left). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. 17-min workout with an emphasis on lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2 10 min of “core compressions” performed in various body positions (2 min quadruped, 2 min wall-sit, 2 min fetal right, 2 min fetal left, 2 min in partial supine-bridge). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature.
3 10 min of “core compressions” performed in various body positions (2 min in quadruped, 2 min in supine spinal twist right, 2 min in supine spinal twist left, 2 min in partial supine-bridge, 2 min in supine with ankles crossed and hips externally rotated). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. 21-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4 9.5 min of “core compressions” performed in various body positions (2 min in quadruped, 2 min seated upright, 1 min standing incline wall plank, 2 min supine with ankles crossed and hips externally rotated, 2.5 min single-leg lifts with hip of active leg in external rotation). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature.
5 10 min of “core compressions” performed in various body positions (2 min quadruped, 2 min wall-sit, 2 min supine spinal twist right, 2 min supine spinal twist left, 2 min partial supine-bridge). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. 21-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6 10.5 min of “core compressions” performed in various body positions (2 min in quadruped, 2 min seated upright, 2 min supine with knees bent, 2 min supine with hips externally rotated and ankles crossed, 2.5 min with single-leg lifts, hip externally rotated). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature.
7 10.5 min of “core compressions” performed in various body positions (2 min in quadruped, 2 min supine spinal twist right, 2 min supine spinal twist left, 2 min partial supine-bridge, 2.5 min with single-leg lifts, hip externally rotated). Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. 15-min restorative workout that includes low-impact aerobic exercises, dynamic stretches, and light resistance exercises.
3 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 11-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

16-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4
5 20-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6 12-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
7
4 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 23-min workout with an emphasis on lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

22-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4
5 26-min workout with an emphasis lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6
7 16-min restorative workout that includes low-impact aerobic exercises, dynamic stretches, and light resistance exercises.
5 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 24-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

16-min workout with an emphasis on lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4
5 13-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6
7 12-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 20-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

25-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4
5 20-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6 12-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
7
7 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 11-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2 12-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

4 22-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
5
6 25-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
7
8 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 26-min workout with an emphasis on lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

22-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4
5 21-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6
7 17-min restorative workout that includes low-impact aerobic exercises, dynamic stretches, and light resistance exercises.
9 1 10 min/day of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 25-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

21-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4
5 20-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6 24-min workout with an emphasis on lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
7
10 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 16-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

23-min workout with an emphasis on lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4
5 12-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6 25-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
7
11 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 24-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
2
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

16-min workout with an emphasis on lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
4
5 13-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6
7 26-min workout with an emphasis on lower body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
12 Education about what exercises to skip/modify to avoid reinjury if they choose to resume workouts and activities outside the program. 1 10 min/d of exercises centered around the abdominal draw in maneuver (“core compressions”) in different positions. Video coaching includes reminders to coordinate TrA muscle contraction with exhalation and engagement of the pelvic floor musculature. The positions include: 15-min restorative workout that includes low-impact aerobic exercises, dynamic stretches, and light resistance exercises.
2 20-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
3
  1. Quadruped

  2. Seated upright against a wall

  3. Standing incline plank with hands against the wall

  4. Wall-sit with neutral spine

  5. Fetal position on the right side

  6. Fetal position on the left side

  7. Supine with knees bent

  8. Supine spinal twist with knees to the right

  9. Supine spinal twist with knees to the left

  10. Partial supine-bridge

  11. Supine with ankles crossed and hips externally rotated

  12. Single-leg lifts with hip of active leg in external rotation

4 25-min workout with an emphasis on total body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
5 20-min workout with an emphasis on core strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
6 16-min workout with an emphasis on upper body strength that incorporates low-impact aerobic exercises, resistance exercises, and gentle stretches.
7

Compliance

All participants were required to complete weekly training logs for the duration of the study. Adherence was monitored by an investigator who was able to observe the frequency with which each participant logged into the exercise program software and if they had watched or engaged with specific videos. This investigator did not do any of the ultrasound measurements. Compliance was defined as performing 50% or more of the online core strengthening exercises throughout the 12-week period. This was determined by engagement per day, so those who performed multiple days' worth of exercises on 1 day were only counted as having completed 1 day of exercises. Similar methods of assessing compliance have been used in other studies.38–40 The outcomes assessor was blinded to the degree of each participant's compliance throughout the study.

Statistical Methods

All data were stored and maintained on REDCap.41,42 Continuous variables are summarized as means and SDs, and discrete variables are summarized as frequencies and percentages. Analyses of the effect of the 12-week core strengthening program on IRD measurements, ICIQ-UI, PSIQ-12, BSQ, and QBPDS were done using linear mixed-effects regression models. The following potential precision variables were included as fixed effects a priori: age, body mass index (BMI), history of abdominal surgery, history of cesarean section, and multiple pregnancies. Residual versus fitted plots for the linear regression models are shown in Supplementary Figure 1 (available at: https://links.lww.com/JWHPT/A50). To determine whether IRD measurements and outcomes were different between 12- and 24-week time points in the subset of women who participated in the maintenance phase, a paired t test was performed. A Bonferroni correction was applied to the family of tests with IRD as the dependent variable. Comparisons of baseline characteristics between included and withdrawn participants, as well as between the maintenance phase subset and the remaining sample, were analyzed using the 2-sample t test for continuous variables and Pearson's χ2 test for discrete variables. Statistical significance was defined as P < .05, unless otherwise indicated. All analyses were performed with Stata, version 14.2 (StataCorp, College Station, Texas).43

RESULTS

Study Recruitment

One hundred twenty-six postpartum women expressed interest in participating between July and November 2018. Seventy women were excluded because they did not meet eligibility criteria. Fifty-six women were initially enrolled (n = 56). Thirteen women were withdrawn; 6 never engaged in the core strengthening program (ie, no activity on exercise program software), 6 stopped participating abruptly and failed to respond to multiple requests to continue program engagement and/or complete weekly training logs, and 1 found out she was pregnant. No follow-up data related to the 12-week program could be obtained from these women, and they were thus excluded from the analysis (Figure 4).

F4
Figure 4.:
Participant flow diagram. The numbers of participants who were assessed, received the intervention, and underwent data analysis are shown. Reasons for exclusion/withdrawal are provided.

Baseline Group Characteristics

Forty-three participants were included in the analysis, with a mean age of 36.7 ± 3.5 years and a mean BMI of 22.9 ± 3.0 kg/m2. Baseline characteristics are shown in Table 2. The mean number of weeks postpartum was 66.8 ± 42.7 weeks, and 22 participants (51%) were currently breastfeeding. Nineteen participants completed the additional 12-week maintenance phase. There were no differences in baseline characteristics between participants who were included in the analysis and participants who were withdrawn due to lack of engagement in the program (see Supplementary Table 1, available at: https://links.lww.com/JWHPT/A49). In addition, baseline characteristics were similar between the participants who completed the 12-week maintenance phase and the remaining sample; the only significant difference was SUI, which was lower in the maintenance phase subset (see Supplementary Table 2, available at: https://links.lww.com/JWHPT/A49).

Table 2. - Demographics and Baseline Information
Overall (n = 43)
Age, mean (SD), y 36.7 (3.5)
BMI, mean (SD), kg/m2 22.9 (3.0)
Number of weeks postpartum, mean (SD) 66.8 (42.7)
Number of pregnancies, n (%)
1 12 (28)
2 12 (28)
3 8 (19)
4 5 (12)
5 5 (12)
6 1 (2)
Multiple gestation pregnancies, n (%) 4 (9)
Number of vaginal deliveries, n (%)
1 8 (19)
2 10 (23)
3 10 (23)
4 1 (2)
5 2 (5)
Number of C-sections, n (%)
1 12 (28)
2 2 (5)
3 1 (2)
Currently breastfeeding, n (%) 22 (51)
History of abdominal surgery, n (%) 7 (16)
IRD above umbilicus, at rest, mean (SD), cm 3.5 (1.1)
IRD above umbilicus, contracted, mean (SD), cm 3.0 (1.0)
IRD below umbilicus, at rest, mean (SD), cm 2.2 (0.8)
IRD below umbilicus, contracted, mean (SD), cm 2.1 (0.8)
LBP-related disability score (QBPDS), mean (SD) 7.8 (10.6)
Stress urinary incontinence score (ICIQ-UI), mean (SD) 3.3 (3.2)
Pelvic floor function score (PISQ-12), mean (SD) 37.3 (4.0)
Body image score (BSQ-16A), mean (SD) 38.0 (12.0)
Abbreviations: BMI, body mass index; BSQ-16A, Body Shape Questionnaire; C-section, cesarean section; ICIQ-UI, International Consultation on Incontinence Questionnaire-Urinary Incontinence; IRD, interrectus distance; PISQ-12, Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Question; QBPDS, Quebec Back Pain Disability Scale; SD, standard deviation.

IRD Measurement Reliability

ICCs for IRD values above the umbilicus were 0.817 at rest and 0.865 during contraction; both were classified as “excellent.” Below the umbilicus, ICCs for IRD values were 0.567 at rest and 0.681 during contraction. The ICC for IRD value at rest below the umbilicus was classified as “fair,” whereas the ICC for IRD value during contraction below the umbilicus was classified as “good.”

12-Week Core Strengthening Program and IRD Measurements

For IRD above the umbilicus, a significant improvement was observed at rest (slope [SD]: −0.56 [0.09]; 95% confidence interval [CI]: −0.74, −0.38; P < .001) following participation in the 12-week online core strengthening program. An improvement was also observed during contraction, but this did not reach statistical significance (slope [SD]: −0.24 [0.12]; 95% CI: −0.47, 0.01; P = .037). For IRDs below the umbilicus, significant improvements were observed at rest (slope [SD]: −0.26 [0.10]; 95% CI: −0.45, −0.06; P = .009) and during contraction (slope [SD]: −0.39 [0.10]; 95% CI: −0.58, −0.20; P < .001) (Table 3).

Table 3. - Effect of 12-Week Core Strengthening Program on Changes in IRD and PROs
Variables Slope (SD) 95% CI P Valuea
IRD above umbilicus, at rest, cm −0.56 (0.09) −0.74, −0.38 <.001
IRD below umbilicus, at rest, cm −0.26 (0.10) −0.45, −0.06 .009
IRD above umbilicus, during contraction, cm −0.24 (0.12) −0.47, 0.01 .037
IRD below umbilicus, during contraction, cm −0.39 (0.10) −0.58, −0.20 <.001
LBP-related disability score (QBPDS) −3.28 (1.08) −5.39, −1.17 .002
Stress urinary incontinence score (ICIQ-UI) −0.74 (0.22) −1.16, −0.31 .001
Pelvic floor function score (PISQ-12) 1.36 (1.01) −0.62, 3.43 .177
Body image score (BSQ-16A) 1.22 (1.52) −1.76, 4.21 .422
Abbreviations: BSQ-16A, Body Shape Questionnaire; CI, confidence interval; ICIQ-UI, International Consultation on Incontinence Questionnaire-Urinary Incontinence; IRD, interrectus distance; PISQ-12, Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Question; PRO, participant-reported outcome; QBPDS, Quebec Back Pain Disability Scale; SD, standard deviation.
aItalics signify Bonferroni-adjusted α/4 = 0.0125.

Secondary Outcomes at 12 Weeks

There were significant decreases in LBP-related disability (QBPDS; slope [SD]: −3.28 [1.08]; 95% CI: −5.39, −1.17; P = .002) and SUI (ICIQ-UI; slope [SD]: −0.74 [0.22]; 95% CI: −1.16, −0.31; P = .001) following participation in the 12-week online core strengthening programs. No differences in pelvic floor function (PISQ-12) and body image (BSQ) were observed (P = .177 and .422, respectively) (Table 3). Additionally, there was no association between IRD measurements and program compliance, multiple gestation pregnancies, or satisfaction.

IRD Measurements and Participant-Reported Outcomes After 12-Week Core Strengthening and 12-Week Maintenance

During the maintenance phase, participants continued with the core strengthening program for an additional 12 weeks. For these 19 participants, outcomes were compared at 24 weeks versus 12 weeks. At 24 weeks, all IRD measurements, except for IRD above the umbilicus during contraction, were significantly lower than those at 12 weeks (P = .007 for IRD above at rest, P < .001 for IRD below at rest, P < .001 for IRD below during contraction). IRD above the umbilicus during contraction was also lower at 24 weeks compared with 12 weeks, but this change was not statistically significant (P = .065). Representative ultrasound images depicting IRD measurements at baseline, 12 weeks, and 24 weeks are shown in Figure 5. There were no differences in any of the participant-reported outcomes following the maintenance phase at 24 weeks, compared with those at 12 weeks (Table 4).

F5
Figure 5.:
Representative IRD measurements at rest 3 cm above the umbilicus for an individual at (A) baseline; (B) 12 weeks (after participation in the core strengthening program); and (C) 24 weeks (after participation in the maintenance phase).
Table 4. - Comparison of IRD and PROs After Initial 12-Week Core Strengthening Program and 12-Week Maintenance Phase
Variables 12 wka 24 wka P Valueb
IRD above umbilicus, at rest, cm 3.5 (1.2) 2.8 (0.6) .007
IRD below umbilicus, at rest, cm 2.2 (0.8) 1.5 (0.5) <.001
IRD above umbilicus, during contraction, cm 3.1 (1.3) 2.6 (0.6) .065
IRD below umbilicus, during contraction, cm 2.0 (0.7) 1.4 (0.4) <.001
LBP-related disability score (QBPDS) 8.6 (11.1) 6.4 (8.0) .153
Stress urinary incontinence score (ICIQ-UI) 2.3 (1.7) 1.6 (2.0) .109
Pelvic floor function score (PISQ-12) 44.6 (2.9) 43.6 (3.3) .493
Body image score (BSQ-16A) 36.0 (12.0) 38.6 (15.9) .456
Abbreviations: BSQ-16A, Body Shape Questionnaire; ICIQ-UI, International Consultation on Incontinence Questionnaire-Urinary Incontinence; IRD, interrectus distance; LBP, low back pain; PISQ-12, Pelvic Organ Prolapse/Urinary Incontinence Sexual Function Question; PRO, participant-reported outcomes; QBPDS, Quebec Back Pain Disability Scale.
aResults are mean (standard deviation) of n = 19; 24 weeks denotes the end of the 12-week maintenance phase.
bItalics signify Bonferroni-adjusted α/4 = 0.0125.

Program Compliance and Satisfaction

Program compliance was reported by 72% of participants (n = 31). Forty participants answered the satisfaction questions. The overall mean satisfaction was 7.43 ± 2.23 on a scale of 0 to 10. Thirty-eight participants (95%) stated that they would recommend the exercise program to a friend.

DISCUSSION

This prospective observational study assessed IRD and participant-reported outcomes following an online, video-based core strengthening program in postpartum women with DRA. IRD measurements at rest were significantly reduced after 12 weeks of the online core strengthening program. Those who completed the program for 12 weeks and then participated in an additional 12-week maintenance phase had significantly greater improvements in their IRD at 24 weeks. There were also significant improvements in LBP-related disability and SUI following the 12-week core strengthening program. Satisfaction with the program was high overall.

Prior work has demonstrated that core strengthening improves DRA, but there is no consensus on the optimal timing, duration, frequency, and type of exercises to correct this issue. In postpartum women, IRD has been shown to decrease while performing an abdominal crunch, but no data exist regarding the long-term effect of this exercise on IRD.11,44 Other core-oriented exercise programs of varying durations and intensities have shown favorable results with regard to decreasing DRA severity and/or IRD.13–16 These exercise programs were predominantly hands-on and conducted in person and may not be as accessible to the general population, compared with online and video-based exercise programs, which offer convenience and flexibility in timing.

In our study, the IRD improvements at 12 and 24 weeks were statistically significant above the umbilicus at rest and below the umbilicus at rest and during contraction. Although not statistically significant, there was also a decrease in IRD above the umbilicus during contraction. Importantly, participants who continued the exercises during an additional 12-week maintenance phase demonstrated significantly lower IRD measurements at 24 weeks compared with 12 weeks. Most women did not see full resolution of their IRD, according to the clinical definition of a separation less than 2 cm. However, data on prepartum IRDs for each participant were not available. Mean IRDs in nulliparous women have been shown to be 2.2 cm at 3 cm above the umbilicus and 1.6 cm at 2 cm below the umbilicus.6 Furthermore, we did not find any correlation between improvement in IRD and BMI, history of abdominal surgery, or history of cesarean sections.

In addition, LBP-related disability and SUI were significantly improved following the 12-week core strengthening program. No differences in pelvic floor function and body image were observed. Unlike IRD, no further significant improvements in LBP-related disability and SUI were observed after the 12-week maintenance phase. It is important to note that disability was low at baseline in this cohort, which may not be representative of the general postpartum population. Most participants were highly motivated and may have been more eager to exercise, compared with those who may suffer considerably from any of these DRA-related sequelae. Furthermore, it is important to note that there is conflicting evidence in the literature with regard to the relationship between DRA and LBP or SUI.45 A higher prevalence of LBP has been demonstrated in both male and female participants with DRA,46 and a significant correlation between DRA and LBP has been shown in pregnant women during the third trimester.47 However, several other studies have shown no relationship between DRA and LBP during pregnancy and up to 12 months postpartum.2,10,48 Similarly, surgical resolution of DRA has been associated with SUI improvement in postpartum women,49 and a higher percentage of runners with DRA reported SUI in the postpartum period,50 but other studies have demonstrated no correlation between DRA and SUI.51,52

This study adds to the limited studies evaluating DRA in postpartum women. The online core strengthening program offers advantages over a hands-on exercise program, as it can be utilized by a greater number of women and can be accessed at any time. This can be especially useful in the current setting of the COVID-19 pandemic, which has led to an increase in the shift from in-person to virtual exercise or rehabilitation programs overall.53 By using ultrasound, instead of the widely used palpation technique, we were able to collect quantitative values for IRD. We also collected multiple participant-reported outcomes that could be compared with the ultrasound measurements. All necessary equipment required for the exercise intervention was provided, and our measurement tools were standardized to the greatest extent possible. Finally, all measurements were collected by a single investigator, with excellent intrarater reliability for measurements above the umbilicus. Intrarater reliability for measurements below the umbilicus ranged from fair to good; this is likely due to differences in the anatomy of the posterior rectus sheath.54

Our findings should be considered in the context of the limitations of the study. First, we had to withdraw 13 women due to lack of participation in the program activity and/or lack of response to weekly logs, which reduced our sample size. It is important to note that no follow-up data were collected from these women, so there was no way to include data from these subjects in an intention-to-treat analysis. Second, there is no agreement as to the width of IRD that is considered to be pathologic. Our cut-off of 2.0 cm might have been too broad, leading to the possible inclusion of women with “normal” IRDs. In addition, because all exercise instructions were provided online through videos, there was no way to ensure that participants were performing the exercises correctly. However, the instructions were repeated during each online session. Furthermore, since the participants were doing the exercises on their own, we had to estimate subject compliance by tracking subjective measures of self-reported participation and when they logged on to do the exercises. This definition of compliance was adapted from existing studies,38,40 but it is possible that we underestimated subject compliance if they had exercised more than they reported on their logs and/or memorized the exercises and did them without logging into the program. Lastly, future research should include a group of participants who do not participate in the online core strengthening program.

CONCLUSIONS

Findings from this study show that a 12-week online core strengthening program, which emphasized isometric recruitment of the transversus abdominis while excluding common forward-flexion exercises (ie, sit-ups, crunches, and crossover crunches), significantly decreased IRD above and below the umbilicus in this cohort of postpartum women. Participation in the exercises for an additional 12 weeks led to a greater decrease in IRD. In addition, satisfaction with the program was high overall, and most participants reported that they would refer the program to a friend. As evidenced by the large number of women who expressed interest in this study within a short period of time, DRA is a huge area of concern for postpartum women. Thus, the online core strengthening program has great potential to improve DRA in postpartum women in a time- and cost-effective manner, as it can be accessed without the need for specific time commitments to in-person sessions. Furthermore, LBP-related disability and SUI have a high burden in postpartum women, and the online core strengthening program effectively improved both conditions in this cohort. Our findings suggest that a video-based core strengthening exercise program offers an accessible and effective treatment strategy for postpartum women with DRA, and further investigation regarding the optimal timing, duration, and sequence of exercises is warranted.

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Keywords:

core strengthening; diastasis rectus abdominis; interrectus distance; musculoskeletal ultrasound; pregnancy

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