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Comparison of Electromyographic Activity of the Superior and Inferior Portions of the Gluteus Maximus Muscle During Common Therapeutic Exercises

Discover the differences in muscle activity when performing typical exercises for the gluteus maximus. A comprehensive analysis comparing the superior and inferior portions of the muscle.

Brent Brookbush

Brent Brookbush

DPT, PT, MS, BS, CPT, HMS, SPC, IMT

Research Review: Comparison of Electromyographic Activity of the Superior and Inferior Portions of the Gluteus Maximus Muscle During Common Therapeutic Exercises.

By Nicholas Rolnick SPT, MS, CSCS

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

Original Citation: Selkowitz DM, Beneck GJ, Powers CM. (2016) Comparison of electromyographic activity of the superior and inferior portions of the gluteus maximus muscle during common therapeutic exercises. JOSPT. 46(9): 794-799. - ARTICLE

Why is this relevant?: It has been hypothesized, that the gluteus maximus has two functionally distinct portions which may be selectively activated depending on the movement pattern. That is, the superior portion of gluteus maximus is more active in motions involving hip abduction, whereas the inferior portion is more active during hip extension. Knowledge of how the gluteus maximus is recruited may have an impact on exercise selection for performance and rehabilitation. The current study compared electromyographical (EMG) activation of the superior and inferior portions of the gluteus maximus muscle in 11 common therapeutic exercises using fine-wire electrodes.

Note the huge muscle mass that is gluteus maximus
Caption: Note the huge muscle mass that is gluteus maximus

Note the huge muscle mass that is the gluteus maximus - https://corawen.com/sacrum-gluteus-dance-links/

Study Summary

Study Design Controlled Laboratory Study - Repeated Measures Design
Level of Evidence IIA Evidence from at least one controlled study without randomization
Subject Demographics
  • Subject Demographics:
    • 20 total subjects (10 males, 10 females)
    • Age ± Standard Deviation (Range) - 27.9 ± 6.2 (18-50) years old
    • Height ± Standard Deviation (in cm) - 170.5 ± 11.1 cm
    • Weight ± Standard Deviation (in kg) - 67.7 ± 14.1 kg

  • Characteristics of the Study Design:
    • Protocol
      • The dominant leg (defined as the leg used to kick a ball) was used for all recordings.
      • Fine-wire electrodes were inserted into the superior and inferior portions of the subjects' gluteus maximus.
        • Superior portion - Electrode was inserted superior and lateral to the midpoint of a line drawn between the posterior superior iliac spine and the posterior greater trochanter.
        • Inferior portion - Electrode was inserted inferior and medial to the midpoint of the same line, approimately 2.5-5.0 cm above the gluteal fold.
        • Electrical stimulation was used to verify correct placement of electrodes:
        • Reference electrode - placed at C7 spinous process

      • Maximum Voluntary Isometric Contractions (MVIC) was performed by each subject in 4 different positions, in random order, using a goniometer to measure specific angles.
        • Position 1 - Resisted hip extension with the hip at 45° of flexion and the knee at 90° of flexion
        • Position 2 - Resisted hip extension with the hip in neutral position and knee at 90° of flexion
        • Position 3 - Resisted hip abduction against a wall with pelvis and scapulae stabilized, and hip positioned in 30° of abduction with knee fully extended.
        • Position 4 - Resisted hip abduction (same position as Position 3), but the hip was positioned in 30° of abduction and 45° of flexion

      • Each subject was familiarized with the testing protocol and practiced the exercises before data collection to ensure proper performance.
      • Each of the 11 exercises were performed in random order for each subject: hip abduction in side-lying, clam with elastic resistance around thighs, bilateral bridge, unilateral bridge, hip extension in quadruped on elbows with knees flexed, forward lunge with erect trunk, squat, sidestepping with elastic resistance around thighs in a squat position, hip hike, and forward step-up
        • Each exercise was performed with a metronome set to 40 beats/minute (except for the side-stepping exercise which was performed at 80 beats/minute)
        • An event marker was manually triggered during each exercise to signal the beginning and end of each repetition
        • Five repetitions per exercise were performed with 1 beat of metronome as rest in-between each repetition
        • Two minutes of rest were given between each exercise

      • Each subject performed the MVIC procedure again after the exercises were completed to ensure that the wires were still functioning and not displaced.

    • Statistical Analysis
      • 2x11 ANOVA was done to compare EMG signal amplitudes between the superior and inferior portions of gluteus maximus during each of the 11 exercises.
      • Paired t-tests were used when significance was detected in the ANOVA to compare superior and inferior portions of gluteus maximus activation.
      • Significance was set at p < 0.05.

  • Inclusion Criteria: N/A
  • Exclusion Criteria:
    • Orthopedic injuries to the trunk or the lower extremity
    • Neurological disorders
    • Pregnancy

Outcome Measures EMG amplitudes of the superior and inferior portions of gluteus maximus in each of the 11 exercises performed
Results

The table is taken from Selkowitz DM, Beneck GJ, Powers CM. (2016) Comparison of electromyographic activity of the superior and inferior portions of the gluteus maximus muscle during common therapeutic exercises. JOSPT. 46(9): 794-799.

ConclusionsSide-lying hip abduction, clamshells , standing hip hikes, side-stepping , and forward step-ups produced greater activation of the superior portion of gluteus maximus in comparison to the inferior portion. All other exercises activated both portions equally.Conclusions of the ResearchersThe different portions of the gluteus maximus muscle are preferentially recruited in different exercises based on the demands of the hip. These findings have potential to influence exercise selection for individuals with lower extremity pathologies which require selective gluteus maximus recruitment and re-education.

Dr. Brookbush teaching an upright lunge.
Caption: Dr. Brookbush teaching an upright lunge.

Upright Lunge

Review & Commentary:

The current study was one of the first studies to investigate the activation patterns of the superior and inferior portions of gluteus maximus . The protocol was clearly described and included detailed descriptions of set-up and data collection procedures. The clarity of the description allows for replication of the study; perhaps using various population. The use of varied positions in determining the maximum voluntary isometric contraction (MVIC) of the gluteus maximus ensured that the highest activation was recorded and used for standardization. Second, the use of fine-wire EMG reduces the likelihood of cross-talk, increasing the accuracy of the data. Third, the exercises selected in this study are those exercises commonly performed in rehab, fitness and performance enhancement settings.

The study had some limitations that should be mentioned. The absence of kinematic analysis during these exercises leaves questions about whether stability, complexity or quality of motion may have impacted gluteus maximus recruitment. The authors concluded that the superior portion of gluteus maximus is more active as a hip abductor and hip external rotator, but that is speculation based on exercise selection alone. Future studies should include kinematic analysis comparing motion capture to each exercise, and then compare with EMG data to further refine findings. There was considerable variation in gluteus maximus activation between subjects, which the authors mentioned is common in EMG studies. Despite these critiques the clear delineation between extension biased and abduction biased exercise does allude to the strength of the study's findings.

Why is this study important?

The current study provides support differential activation of the superior portion of gluteus maximus . Specifically, the superior portion of gluteus maximus is preferentially activated during hip abduction and external rotation; whereas, both the superior and inferior portions of gluteus maximus are activated similarly with hip extension.

How does it affect practice?

These findings may have implications for human movement professionals designing exercise interventions for individuals with lower extremity pathology. For example, it may be important to consider the superior portion of the gluteus maximus when attempting to reduce functional valgus - selecting exercises with a bias toward hip abduction and external rotation, such as side-lying hip abduction , clamshells , standing hip hikes, side-stepping , and forward step-ups . This may be followed by hip extension biased exercise to integrate the entire gluteus maximus using traditional strength training exercises like forward step-up, forward lunge , squat .

How does it relate to Brookbush Institute Content?

In lumbo pelvic hip complex dysfunction (LPHCD ), sacroiliac joint dysfunction (SIJD ), and lower leg dysfunction (LLD ), the gluteus maximus is commonly classified as "long/under-active." Further, the sign "Knees bow in (functional valgus) " sign during the Overhead Squat Assessment is characterized by excessive femoral internal rotation and adduction. This study implies these dysfunction may involve a larger reduction in activity of the superior fibers than inferior fibers of the gluteus maximus . Based on this study the techniques used by the Brookbush Institute for correcting glute complex under-activity appear to be directed at the gluteus medius , and preferential recruitment of the the superior portion of the gluteus maximus . Of the 11 exercises tested, clamshells  elicited the most EMG activity of the superior portion of gluteus maximus , indicating that clamshells may be used for both the gluteus medius , and for "isolation" the superior portion of gluteus maximus . Clinically, the Brookbush Institute has noted a better response from side-lying hip abduction and gluteus maximus activation exercises when preceded by a set of clamshells .

The following sample intervention is designed as a gluteus maximus activation circuit to increase activation of the entire muscle and address the movement dysfunction "knees bow in ".

Perform each exercise for 12-20 reps with a weight that is challenging, but ensures that ideal form is maintained. Perform in a circuit (without rest between exercises) 1-2 times through.

  1. Clamshells (Isolated Activation)
  2. Prone Ball Unilateral Hip Extension (Isolated Activation)
  3. Dynamic Ball Bridge with Trunk Rotation (Core Integration)
  4. Single Leg Dead-lift Touchdown (Integrated Stabilization)
  5. Transverse Plane Hop to Stabilization (Reactive Integration)
  6. Reverse Lunge to Unilateral Row (Sub-system Integration)
  7. Glute and Core Taping (Reinforce)

The videos below depict assessment of gluteus maximus and initial steps to addressing its under-activity in postural dysfunction.

Brookbush Institute Videos

Gluteus Maximus Manual Muscle Test

Gluteus Medius Isolated Activation (Clamshells)

Gluteus Maximus Isolated Activation

TVA and Gluteus Maximus Activation and Progressions

© 2016 Brent Brookbush

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