Research Review: Role of the Diaphragm in Stabilization
By Jinny McGivern DPT, PT, Certified Yoga Instructor
Edited by Brent Brookbush DPT, PT, MS, PES, CES, CSCS, ACSM H/FS
Original Citation: Hodges, P. W., Butler, J. E., McKenzie, D. K., & Gandevia, S. C. (1997). Contraction of the human diaphragm during rapid postural adjustments. The Journal of physiology, 505(Pt 2), 539-548. - ABSTRACT
Kinesiology taping to promote diaphragm facilitation.
Why is this relevant?: The diaphragm is often described as a core stabilizing muscle, working in conjunction with the transverse abdominis (TVA) , pelvic floor and multifidi to provide stability to the spine & trunk. The exact nature of how the diaphragm functions as a core muscle is not often described in detail. This research provides direct evidence of diaphragm muscle contraction related to postural stabilization, not respiratory function. Furthermore this research provides support that the diaphragm functions synergistically with another core stabilizing muscle, the TVA .
Study Summary
| Study Design | Cross sectional laboratory study - Descriptive study |
| Level of Evidence | Level VI - Evidence from a single descriptive or qualitative study |
| Subject Demographics |
|
| Outcome Measures | This study consisted of 3 different protocols where 3 different sets of outcome measures were examined.#1 The following were collected during 20 reps of standing shoulder flexion to 90 degrees performed "as fast as possible" in response to a random visual stimulus: EMG readings and onset of timing of:
Pressures (collected using a gastro-esophogeal catheter):
Respiratory cycle (measured via inductance plethysmograph)
#2 The following was collected from 2 subjects during 10 reps of fast as possible movement for each body part cued by a visual stimulus: EMG readings for the onset of each of the following segment movement, as well as diaphragm:
# 3 The following was collected for 4 subjects via ultrasound during 10 reps of shoulder flexion and at resting end expiratory volume: Diaphragm motion in response to shoulder
|
| Results | #1 Responses to shoulder flexion
#2 EMG activity of diaphragm as related to motion of specific segment of the UE.
#3 Length changes of diaphragm relative to timing of shoulder movement
|
| Conclusions | This research supports the inclusion of the diaphragm as a member of our "core" musculature based on its co-contraction with other members of the intrinsic stabilization subsystem in response to a challenge to postural stability. The mechanism by which the diaphragm aids in creating core stability is by increasing intra-abdominal pressure to increase support of the spine. |
| Conclusions of the Researchers | The findings of this study indicate that the diaphragm contracts with the TVA prior to movement of the upper limb (larger movements, not fine motor), regardless of the phase of respiration. Because the diaphragm's response appears to be dependent on the scale of the movement performed, this indicates a role as a stabilizing postural muscle. |
Image of the inferior aspect of the diaphragm with sternal, costal and crural (right crus & left crus) sections indicated - https://anatomytopics.wordpress.com/files/2009/01/diaphragm-inf-view.jpg
Review & Commentary:
There were many features of this study that contributed to it's strong methodology. The researchers elected to observe the behavior of two members of the "core" or "deep stabilizers," in response to postural perturbations related to upper extremity movement. As a lack of core stabilization is typically cited as a contributing factor to many movement impairments, this study illustrates the role the TVA and Diaphragm may play. With respect to data collection, the use of surface EMG readings was not an option. The diaphragm & TVA are deep structures with layers of overlying muscle that would have interfered with the accurate assessment of muscle activity. Needle electrodes were used with exact placement determined by ultrasound imaging and confirmed with EMG readings. To make their study multi-dimensional, the authors observed the onset of electrical activity of the diaphragm (EMG readings), it's mechanical behavior (shortening and lengthening), and the changes in pressure in the thorax and abdomen. By examining all of these components simultaneously, the researchers were able to study how these different components were inter-related.
A major limitation of this study was its small sample size and differing numbers of subjects for different components of the research study. The largest number of individuals for any 1 set of data was 5 and the lowest was 2. It would have been beneficial if all data points could have been collected from all 5 subjects. It would be ideal if future researchers could reproduce this methodology with a larger sample size. In terms of subject selection, the individuals chosen were screened for neurologic and respiratory conditions that might impact results. The researchers do not mention screening subjects for any orthopedic conditions, in particular low back pain. Other research reviews on this website have focused on how core musculature can become inhibited in the event of injury, pain or pathology. Could the diaphragm's function as a core stabilizer become inhibited in similar ways to multifidi or TVA ? Future research is needed to examine the effect of pain on the diaphragm.
Why is this study important?
This study is important because it provides evidence to support established theory of the diaphragm's role as a deep core stabilizing muscle, and potentially targeted assessment and intervention.
How does it affect practice?
This study in particular does not provide much direct insight into the practical applications of improving the diaphragm's function as a core stabilizer; however, it does encourage the human movement professional to take note of this muscle. One method of assessing the diaphragm's function is to observe breathing. Although this article focuses on the stabilizing role of the diaphragm, it is reasonable to consider - if the muscle is impaired in its respiratory function, it may be impaired in it's stabilizing function as well.
The Assessment: Have your patient or client lie on their back with their knees bent and feet flat on the floor. Ask them to take a deep breath. Observe where you see movement. Is it primarily in the upper chest, lateral rib cage or is the gentle rise of the abdomen? You know that your client is breathing diaphragmatically if you see a gentle expansion of the abdomen and lower rib cage. If you don't see any movement of the abdomen on inhalation, it may be presumed that the diaphragm is not functioning optimally.
The Intervention: Ask your client to place 1 hand on their chest & 1 hand on their abdomen as they breathe. Encourage him or her to notice where the most movement is happening. Then, ask your client to gently breathe into their abdomen (One cue that works well is "Imagine you are inflating a balloon"). Some individuals will try to push their abdomen out. This is not the goal looking for - reset, re-cue a gentle, broadly distributed expansion of the abdomen, and reassess.
On a personal note, with a background as a yoga instructor, I have always been interested in the "breath" and how it has the capacity to influence movement. I frequently incorporate the above intervention into my patient/client's home exercise program, especially those with low back pain. Patients have reported that this technique was helpful in managing their pain. It is difficult to say (in this very unscientific, non-controlled observation) if it was the improved function of the diaphragm as stabilizer, or if this reduction in pain was related to relaxation, enhanced parasympathetic nervous system activity, or other factors.
How does it relate to Brookbush Institute Content?
This research supports the inclusion of the diaphragm in the Intrinsic Stabilization Subsystem (ISS) , as described by the Brookbush Institute (influenced by the work of Richardson, Hodges and Vleeming). Within the paradigm of subsystems tending toward overactivity or under-activity based on observed movement impairment and predictive models of postural dysfunctions , the ISS is believed to adopt a compensation pattern that includes relative under-activity in all predictive models of postural dysfunctions . This often results in synergistic dominance of other subsystems (i.e. the Anterior Oblique Subsystem (AOS) ) as they attempt to compensate for impaired trunk and spine stabilization. This often has ramification on movement (i.e. compensations) at peripheral joints. Based on this, activation activities are essential to increase neural drive to the muscles included in this subsystem. These activities are typically performed during a corrective exercise routine/integrated warm-up, or at the beginning of a performance enhancement routine so that the core is involved from the start of a workout. ISS activation activities are especially important to the predictive models of postural dysfunction intimately related to the trunk and spine, i.e. Lumbo Pelvic Hip Complex Dysfunction and Sacroiliac Dysfunction. It is not far fetched to reason that individuals with Upper Body Dysfunction and Lower Leg Dysfunction might also demonstrate inhibition of the ISS , although other interventions that more directly address those dysfunctions are typically employed first.
The Brookbush Institute primarily addresses the ISS via activation exercises targeted for TVA (specifically the "Quadruped") (although there may be more to come in the future). Below are videos with details of these exercises as well as a video with a brief explanation of subsystems.
Transverse Abdominis TVA Isolated Activation
TVA and Gluteus Maximus Activation and Progressions
Hardest Quadruped Progression Ever Challenge
Review of Core Subsystems
© 2014 Brent Brookbush
Questions, comments, and criticisms are welcomed and encouraged -