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Tuesday, June 6, 2023

Gluteus Maximus Stabilization Forces at the Sacroiliac Joint

Brent Brookbush

Brent Brookbush


Research Review: Gluteus Maximus Stabilization Forces at the Sacroiliac Joint

By Stefanie DiCarrado DPT, PT, NASM CPT & CES

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

Original Citation: Barker, PJ., Hapuarachchi, K.S., Ross, J.A., Sambaiew, E., Ranger, T.A., and Briggs, C.A. (2013) Anatomy and biomechanics of gluteus maximus and the thoracolumbar fascia at the sacroiliac joint. Wiley Online Library. DOI: 10.1002/ca.22233 ABSTRACT

glute max
Caption: glute max

Image courtesy of Barker, Hapuarachchi, Ross, Sambaiew, Ranger, and Briggs (2013)

Why is this relevant?: As mentioned in the article: Gluteus Maximus: Superficial & Deep Fibers , cadaver dissections have revealed deep fibers of the gluteus maximus that only invest in the sacrum and ilium (that do not cross the hip). Further, a large majority of the cross-sectional area of the gluteus maximus can be attributed to fibers that cross both the sacrum and hip, implying that the gluteus maximus may have a special role in stabilization of the sacroiliac joint (SIJ) . This study takes the next step by investigating the amount of force these fibers can generate and the resulting compressive force on the SIJ, so that we may hypothesize the contribution of the gluteus maximus to SIJ stabilization.

Study Summary

Study Design Descriptive
Level of EvidenceLevel IV: Evidence from a single descriptive or qualitative study 
Subject Demographics
  • Age: 54-90 years old (deceased)
  • Gender:  2 female, 4 male
  • Characteristics:  Cadaver dissection, 11 gluteus maximi dissected
Outcome Measures
  • Fascicle origins & orientation
  • Fascicle bundle length
  • Fascicle bundle volume
  • Fascicle bundle PCSA
  • Maximum possible force generated by fascicle bundle
  • Maximum compressive force at SIJ & extension moment at lumbar spine.
  • Fibers crossing the SIJ comprised 70% of the PCSA
  • 67% of fibers inserted into the IT band; 33% inserted on gluteal tuberosity
  • 10% of the gluteus maximus attached proximally to the thoracolumbar fascia (TLF) and erector spinae aponeurosis
  • Fascicle origins (listed superolateral to inferomedial attachement sites, & superficial fibers to deep fibers,*indicates it crosses SIJ)
    • Gluteus medius fascia
    • Ilium
    • *TLF: aligned inferiomedially between the inferior border of the posterior superior iliac spine (PSIS) to a point on the sacrum 1-2cm lateral to S3.
      • Proximal fibers crossed midline between L3 & S3

    • *Erector Spinae Aponeurosis: fascicles lie deep to the lateral border of TLF
    • *Long dorsal sacroiliac ligament
    • *Sacrum
    • *Sacrotuberous ligament (STL)
    • *Coccyx

  • Fascicle Orientation:
    • Transitions from 32° proximally to 45° distally

  • Fascicle bundles lengths
    • Longest for sacral and coccygeal origins
    • Shortest for gluteus medius fascial origins

  • Fascicle bundles mean volume
    • Greatest for sacral origin fascicles, followed by ilium, STL, and coccygeal origins (all others were smallest & about equal)

  • Total PCSA = 26cm2
  • Force Generated
    • The average maximum generated force predicted by all attachments crossing SIJ = 891N, 70% of which potentially exert forces perpendicularly to the plane of the SIJ.
    • Sacral attachments provided the greatest compressive forces at the SIJ (35%), followed by fibers of STL origin (23.5%).  The remaining fiber attachment sites provided 13-14% each.
    • Fibers attached to either the TFL or erector spinae aponeurosis can produce a maximum sagittal shear force of 59N which creates a 4Nm extension moment across the L3-L5 lumbar segments.

ConclusionsGluteus maximus consists of fibers with multiple origins of both muscle and bone.  There were a significant number of superficial and deep fibers that cross, and therefore have an effect on, the SIJ.  Fibers originating from the TLF are typically used for EMG readings and can be considered a superficial layer.  Muscle activity here may not accurately reflect motor unit recruitment in the deeper fibers and lead to false impressions of gluteus maximums activity and stabilization forces. Through the TLF, the gluteus maximus can exert force up to the level of L3 and may lead to compensatory lumbar extension when hip extension is not biomechanically available.
Conclusions of the ResearchersCadaver dissection and calculation of the PCSA of the gluteus maximus muscle sacral fibers provides further evidence that this muscle can contribute to SIJ stabilization.  Attachments via TLF allows for transfer of forces between the trunk and the lower extremities and could produce extension in the lower lumbar region.

Review & Commentary:

Cadaver dissection provides higher quality information about muscle fiber attachments than can be attained from current imaging technology. Further, the ability to exert a force on individual fibers, without the interference of neighboring structures, allows us to consider how those individual fibers contribute to compressive, arthrokinematic or osteokinematic motions. Using cadavers does have marked disadvantages. Typically cadaver dissection means the analysis of older and possibly atrophied muscles which may result in data that does not apply to a younger, healthy population. Additionally, posterior cadaver muscles such as the gluteus maximus may be flattened from the supine position used in cadaver preparation, making the muscle fibers appear more horizontal in some areas than they would in vivo. Although the sample size in this study (n= 11 muscles) was small, the findings did not vary significantly between the bodies, implying high reliability. The information gathered in a cadaver dissection of this nature provides further insight into the functional anatomy of the human body, moving beyond gross anatomy, and adds to the picture of human movement science we seek to complete in our search for congruence .

Why is this study important?

This study supports the findings of a previously reviewed article Gluteus Maximus: Superficial and Deep Fibers that, through cadaver dissection, documented deep fibers of the gluteus maximus exclusively crossing the SIJ and contributing to its stability. The current study investigated not only fiber bundle (fascicle) origins but their orientation, cross sectional areas and predicted force generation to further understand how the gluteus maximus can provide a stabilizing compressive force at the SIJ.

How does it affect practice?

Through its attachment to the TLF (unique to humans), the gluteus maximus is a component of the Posterior Oblique Subsystem , and as such contributes to stabilization of the kinetic chain and the transfer of forces from the lower extremities to the trunk and upper extremities. This study validates gluteus maximus activation and/or motor control training as an integral part of any exercise program to target low back pain, SIJ pain, and pelvic instability due to the combination of significant compressive force and perpendicular alignment at the SIJ. It is unclear at this time if the deeper fibers that produce a compressive force at the SIJ are activated with general gluteus maximus activation or if they will require a different exercise for motor unit recruitment.

How does it relate to Brookbush Institute Content?

The relationship between under-activity of the gluteus maximus and SIJ dysfunction is noted in the predictive model of Sacroiliac Joint Dysfunction (SIJD) , as well as Lumbo Pelvic Hip Complex Dysfunction (LPHCD). This study may be evidence of the cause of this relationship, as opposed to the simple observation and hypothesis used to construct the model. Further, this study provides evidence of the relationship between the gluteus maximus , latissiumus dorsi , thoracolumbar fascia, lumbar and sacral joints, and their importance in stability of the SIJ via the Posterior Oblique Subsystem (POS) (Brookbush Institute includes the gluteus medius in the POS). Previous evidence discussed in Gluteus Maximus: Superficial and Deep Fibers  indicates the gluteus maximus may co-contract with the transverse abdominis . To that point, this study's findings suggest that TVA Activation  and Gluteus Maximus Activation  must be considered when addressing LPHCD & SIJD.

Transverse Abdominis (TVA) Isolated Activation

Gluteus Maximus Isolated Activation

TVA and Gluteus Maximus Activation and Progressions

Gluteus Maximus Reactive Integration

Squat to Row (Posterior Oblique Subsystem Integration)

Static Lunge to Row POS Integration Progressions

Reverse Lunge to Row Posterior Oblique Subsystem Progressions

Squat to Row Sled Pull (Power progression for Posterior Oblique Subsystem)

Review of Core Subsystems

Gluteus Maximus Snippet from Functional Anatomy Rowan U

© 2014 Brent Brookbush

Questions, comments, and criticisms are welcomed and encouraged