Facebook Pixel
Brookbush Institute Logo

Tuesday, June 6, 2023

Drawing-in Offers Greater Sacroiliac Joint Stability than Abdominal Bracing

Brent Brookbush

Brent Brookbush


Research Review: "Drawing in" Offers Greater Sacroiliac Joint Stability than Abdominal Bracing

By Stefanie DiCarrado DPT, PT, NASM CPT & CES

Edited by Brent Brookbush DPT, PT, MS, PES, CES, CSCS, ACSM H/FS

Original Citation: Richardson, C., Snijders, C., Hides, J., Damen, L., Pas, M., Storm, J. (2002) The Relation Between the Transversus Abdominis Muscles, Sacroiliac Joint Mechanics, and Low Back Pain. Spine. 27 (4), 399-405 - ARTICLE

Abdominal Drawing in Manuever. Notice how the back stays stable and the abdominal cavity draws inward.
Caption: Abdominal Drawing in Manuever. Notice how the back stays stable and the abdominal cavity draws inward.

Abdominal bracing. Notice how the back stays stable and the abdominal cavity draws inward. -https://www.allinahealth.org/mdex/ND0008G.HTM

Why is this relevant?: "Drawing in," also known as, transverse abdominis (TVA) activation is often the first cue given by a human movement professional when guiding an individual through an exercise or movement pattern. "Bracing" is an alternative approach to lumbar stabilization involving an isometric contraction of both deep and superficial trunk musculature. Controversy regarding which method better accomplishes the goal of lumbosacral stabilization exists among human movement professionals. This article provides evidence indicating that "drawing in" creates a greater degree of sacroiliac joint (SIJ) stability and may assist in reducing low back pain (LBP). Using this information, human movement professionals can improve cuing and exercise selection for those with SIJ dysfunction (SIJD) and LBP.

Study Summary

Study Design Randomized cross over
Level of Evidence IIa: controlled study without randomization
Subject Demographics
  • Age:  26 years (mean)
  • Gender: 8 males, 5 females
  • Characteristics: healthy, young individuals without a history of low back pain
    • Height: 1.78m (mean)
    • Weight: 74kg (mean)

Outcome MeasuresPrimary: Percent vibration transmitted from ilium to the sacrum.

Secondary: Real time ultrasound imaging of TVA, external obliques (EO), internal obliques (IO), and rectus abdominis (RA) contraction (increased depth of muscle) & surface EMG activity of EO, erector spinae (ES) (Muscle recruitment strategies were confirmed by surface EMG)

  • Both drawing-in and bracing increased SIJ stiffness.
  • Drawing-in increased SIJ stiffness more by a statistically significant margin (TVA contraction decreased sacral laxity to almost complete stiffness)
  • Higher EMG activity in EO and ES during bracing; minimal activity during draw in
  • Lumbar multifidus (LM) fired along with TVA during draw in  
ConclusionsContraction of the TVA (with co-contraction of the LM) offers a superior means of SIJ compression allowing for increased SIJ stability and improved force transfer during upper and lower extremity movements.
Conclusions of the ResearchersContraction of the TVA during "drawing-in" provides better SIJ stability when compared to abdominal bracing.  The "drawing in" technique should be considered during any rehabilitation program addressing low back pain or SIJ dysfunction, and may be beneficial during performance enhancement programs to increase efficiency of force transfer between upper and lower extremities.

Illustration of the various layers of anterior abdominal muscles
Caption: Illustration of the various layers of anterior abdominal muscles

Public Domain, https://commons.wikimedia.org/w/index.php?curid=789657

Review & Commentary:

Despite a small sample size, this study provides strong evidence that TVA  activation enhances SIJ stability and may prevent or aid in rehabilitation from SIJD and LBP. The authors used young, healthy individuals as subjects to ensure optimal muscle recruitment strategies. Subjects were excluded from the study if they had any of the following: history of low-back pain, severe trauma, respiratory illness, asthma, surgery to the trunk, pregnancy, obesity, scoliosis, and if they were under-going intensive sports training for competition. The researchers further strengthened their data collection by evaluating muscle contractions using surface EMG and real-time ultrasound to confirm the appropriate muscle recruitment for each technique (The TVA , EO , IO , and RA  for bracing and only the TVA  for drawing in). EMG activity of the EO and ES during each trial was compared to maximum EMG activity recorded during each subjects maximal voluntary exhalation.

The researchers maintained adequate standardization in regards to surface EMG electrode placement and testing procedures. The placement of electrodes bilaterally on the anterior and posterior trunk was described in sufficient detail to allow future replications of the study using various populations. Subjects attended a practice session at least one day prior to testing to ensure familiarization with procedures, but were instructed to not to practice the techniques the day of testing to avoid muscle fatigue.

Subjects maintained a prone position during testing so that their SIJ remained in a "stationary, neutral, unloaded position" (404). Researchers tested only the left SIJ but monitored bilateral muscle groups. The testing procedure involved vibration of 200Hz on the subjects left anterior superior iliac spine (ASIS). A Doppler imaging transducer recorded the vibration transmitted through the ilium and through the sacrum. A large disparity between levels of vibration implied the SIJ laxity, a small disparity in vibration implied SIJ stiffness.

Subjects performed two trials of each contraction with a standard two minute rest in between each trial. Subjects then stood up and moved their limbs in an effort to "reset" the body's resting state before testing commenced for the second type of abdominal contraction. The order in which subjects performed the abdominal contractions was randomized.

Interestingly, the degree of sacral laxity consistently decreased in the second trial leading the researchers to conclude the muscles involved did not fully relax during the mandatory two minute rest. The authors did not comment if EMG activity remained elevated or if ultra-sound imaging recorded increased muscle thickness on the second set of contractions (implying muscular contraction).

As mentioned by the authors, the limitation of this study is that these strategies were performed under cognitive control. Further research is required to confirm the transfer of skill post exercise intervention on muscle recruitment patterns during functional activities.

A follow-up study may also compare SIJ stiffness when asked to "draw-in" versus "drawing-in and bracing", versus "drawing-in, bracing, and the valsalva maneuver” at the same time. Functional activities may require a progression of muscle recruitment in response to increasing loads.

Why is this study important?

This study is important because it presented data that indicates the drawing-in maneuver is a more effective strategy for stabilizing the SIJ than bracing alone. It was the first study to compare these different protocols of active lumbar stabilization. More specifically, it was the first study to support the biomechanical model introduced by Erasmus University in Rotterdamn, Netherlands. This model noted transversely oriented muscles (TVA , IO , piriformis , and pelvic floor muscles) as the primary stabilizers of the SIJ due to their orientation perpendicular to the almost vertical alignment of the SIJ. The authors described this model and the implications of related exercises that target LBP rehabilitation in the text - A Motor Control Approach for the Treatment and Prevention of Low Back Pain: 2nd Edition.

Although this study focused on TVA contraction vs contraction of all abdominal muscles (TVA , IO , EO , RA ), the authors note the possible involvement of other stabilizing muscular during the draw-in maneuver (co-contraction of the LM , pelvic floor, and diaphragm). This group of local intrinsic core stabilizers can offer something the larger global muscles cannot - lumbar segmental stabilization. his could be a contributing factor to increased joint stiffness when drawing-in versus bracing.

How does this affect practice?

This study suggests the “drawing-in” maneuver should be cued during exercise and integrated into LBP and SIJD  treatment strategies, and may be beneficial during performance enhancement programs to increase efficiency of force transfer between upper and lower extremities.

How does it relate to Brookbush Institute Content?

The Brookbush Institute consistently emphasizes verbal and manual cues to “Draw-in” during all activities, and isolated activation of the TVA  (when an individual exhibits signs of dysfunction) during rehabilitation, fitness, and performance enhancement programs. The spinal stabilization provided by the TVA  is recognized throughout the predictive models of Lumbo Pelvic Hip Dysfunction Sacroliac Joint Dysfunction , and Upper Body Dysfunction . The following videos emphasize proper technique to activate the TVA .

Note: The Brookbush Institute does not view "drawing in" and "bracing" as two opposing techniques, but rather a progression of muscle recruitment to increase stability/ridigidity of the lumbar spine.

From the article "Transverse Abdominis ":

"In summary, neuromuscular re-education of the intrinsic stabilization subsystem should be addressed first, followed by re-education and conditioning of the global musculature (core subsystems ), and finally integration into functional activities. All steps are necessary for a complete recovery from low back pain or attaining optimal performance. “Drawing in” should be sufficient for stabilization of the lumbar spine and pelvis during most daily activity – that is activity without an added external load or significant increase in velocity. “Bracing” is necessary during an individuals higher intensity activity – this could range from reaching overhead in an older individual, to loaded activities like carrying groceries in the middle-aged and healthy, to weight lifting and sport in the athletic population. Cue the “drawing-in” maneuver during all activities, and “bracing” when appropriate. Even the valsalva maneuver may be considered a progression from "drawing in" and "bracing" for the upper limits of individuals capacity, i.e. 1 Rep Max."

TVA Isolated Activation

TVA and Gluteus Maximus Activation and Progressions


  1. Carolyn Richardson, Paul Hodges, Julie Hides. Therapeutic Exercise for Lumbo Pelvic Stabilization – A Motor Control Approach for the Treatment and Prevention of Low Back Pain: 2nd Edition (c) 2004 Elsevier Limited

© 2014 Brent Brookbush

Questions, comments, and criticisms are welcomed and encouraged -