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