Research Review: Evidence of Altered Corticomotor Excitability Following Targeted Activation of Gluteus Maximus Training in Healthy Individuals

By Jacky Au PhD, CPT

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

Original Citation:

Fisher, B. E., Southam, A. C., Kuo, Y. L., Lee, Y. Y., & Powers, C. M. (2016). Evidence of altered corticomotor excitability following targeted activation of gluteus maximus training in healthy individuals. Neuroreport, 27(6), 415-421. ABSTRACT

Introduction:

The gluteal complex (gluteus maximus , medius , and minimus ) is often targeted during lower-extremity rehabilitation and strengthening programs. Specifically, activation exercises are recommended for the gluteus maximus (GM ) to preferentially recruit the muscle, increase neuromuscular drive and enhance recruitment (1). The goal of this 2016 study from the University of Southern California was to study the neural changes associated with GM activation exercise. Using combined neurostimulation and electromyography (EMG) methods, researchers found increased excitatory and inhibitory inputs to the GM after intervention. This may imply that GM activation  is effective in part due to enhanced corticomotor adaptations.

Caption: Image of Transcranial Magnetic Stimulator (TMS)

Transcranial Magnetic Stimulator (TMS) By Baburov - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=39754391

Study Summary

How this study contributes to the body of research:

A one-week home training program of gluteus maximus (GM ) activation resulted in a significant increase in corticomotor excitability as well as changes in inhibitory processes of the GM . Prior research has demonstrated adaptations of the motor cortex following exercise; however, the exercises were complex movements and adaptation was attributed to skill acquisition (3-8). Unique to this study is the demonstration that motor cortex adaptations occur and may contribute to the benefits achieved by GM activation; a movement pattern requiring minimal skill.

How the Findings Apply to Practice:

This study not only demonstrated that motor cortex adaptations occur and may contribute to the benefits achieved by GM activation , but that these adaptations were achieved using an exercise that was recommended for home use. Assessment of GM strength should be included for individuals exhibiting signs of Lumbopelvic Hip Complex Dysfunction , Sacroiliac Dysfunction , and/or Lower-Extremity Dysfunction . The inclusion of GM activation techniques can be confidently recommended for supervised and in-home programs.

Strengths

1. The use of transcranial magnetic stimulation and motor evoked potentials was a novel way to investigate the neuromuscular adaptations to corrective/therapeutic exercise.
2. This study filled a gap in the research by demonstrating that simple exercise techniques resulted in corticomotor adaptation, as opposed to previous studies that demonstrated adaptation to more complex tasks.
3. Neuro-navigation increased intra-subject reliability of TMS coil placement.
4. Minimal equipment was required for this exercise, making it easily applicable to practice.

Weaknesses and Limitations

1. The cohort consisted of injury/pain-free participants; therefore, generalizability to those with lumbar spine, hip or lower-extremity injuries is limited.
2. The study did not mention if the participants had exercise experience, which may influence additional motor learning or corticomotor adaptations.
3. It is unfortunate that GM  strength was not assessed to determine if adaptation was dependent on level of inhibition/strength.

How the study relates to Brookbush Institute Content?

The Brookbush Institute (BI) continues to develop and refine predictive models of dysfunction, such as Lumbo-Pelvic-Hip Complex Dysfunction (LPHCD) , to aid in education and practical application of human movement science research. This study demonstrates that corticomotor adaptations may contribute to the effectiveness of activation techniques, and that one-week of GM activation  was sufficient to result in corticomotor adaptations. The BI will continue to integrate studies like this to enhance understanding of corrective interventions, refine recommendations, and pursue an evidence-based, systematic approach for attaining optimal outcomes.

Related Videos:

The following videos illustrate common interventions used for gluteus maximus activation :

Gluteus Maximus Isolated Activation

http://player.vimeo.com/video/82855853

Transverse Abdominis and Gluteus Maximus Activation and Progressions

http://player.vimeo.com/video/82877282

Gluteus Maximus Reactive Activation

http://player.vimeo.com/video/76690982

Gluteus Maximus Reactive Activation Progressions

http://player.vimeo.com/video/76690880

Bibliography:

1. Reiman MP, Bolgla LA, Loudon JK. A literature review of studies evaluating gluteus maximus and gluteus medius activation during rehabilitation exercises. Physiotherapy Theory and Practice. 2012 May 1;28(4):257–68.
2. Fitzgerald PB, Fountain S, Daskalakis ZJ. A comprehensive review of the effects of rTMS on motor cortical excitability and inhibition. Clinical Neurophysiology. 2006 Dec 1;117(12):2584–96.
3. Gallasch E, Christova M, Krenn M, Kossev A, Rafolt D. Changes in motor cortex excitability following training of a novel goal-directed motor task. Eur J Appl Physiol. 2009 Jan;105(1):47–54.
4. Hirano M, Kubota S, Koizume Y, Funase K. Acquisition of motor memory determines the interindividual variability of learning-induced plasticity in the primary motor cortex. Journal of Applied Physiology. 2018 Jul 5;125(4):990–8.
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6. Tennant KA, Adkins DL, Scalco MD, Donlan NA, Asay AL, Thomas N, et al. Skill learning induced plasticity of motor cortical representations is time and age-dependent. Neurobiol Learn Mem. 2012 Oct;98(3):291–302.
7. Dayan E, Cohen LG. Neuroplasticity Subserving Motor Skill Learning. Neuron. 2011 Nov 3;72(3):443–54.
8. Kawai R, Markman T, Poddar R, Ko R, Fantana AL, Dhawale AK, et al. Motor Cortex Is Required for Learning but Not for Executing a Motor Skill. Neuron. 2015 May 6;86(3):800–12.
9. Wilson J, BPhty EF, BPhty AH, Maitland L, BPhty CT. A structured review of the role of gluteus maximus in rehabilitation. New Zealand Journal of Physiotherapy. 2005 Nov;33(3) 95-100.
10. Jonkers I, Stewart C, Spaepen A. The complementary role of the plantarflexors, hamstrings and gluteus maximus in the control of stance limb stability during gait. Gait & Posture. 2003 Jun 1;17(3):264–72.

© 2019 Brent Brookbush

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