Evidence for DNS: Diaphragmatic dysfunction in low back pain patients

by Dr. Phil on April 10, 2012

I’ve been a fan of Pavel Kolář’s work in merging the work of Vojta and Janda. Dr. Janda said Pavel was one of his best students, and often pointed to his emerging work with developmental kinesiology at the time and its implications in rehabilitation. I’ve attended several of the “pre-DNS” (Dynamic Neuromuscular Stabilization) courses including one at Motol Hospital in Prague. As with Janda, I’ve been challenged to support Prague School theories with evidence. Much of the Prague School evidence is rooted in the teaching and daily practice of ‘founders’ Janda, Lewit, Vojta, and Vele. I was very pleased to see a paper authored by Kolář and colleagues in Prague in the recent issue of Journal of Orthopedic and Sports Physical Therapy.

One of the main tenets of DNS according to Kolář is the importance of the diaphragm in providing both trunk stabilization and respiration function. Janda spoke of the diaphragm as a muscle prone to inhibition, and Lewit described the ‘core’ as a neurologically-connected group of 4 muscles: transverse abdominus, multifidus, diaphragm, and pelvic floor. Subsequent work by Australian researchers at the University of Queensland found that not only were these muscles often poorly activated (both in intensity and speed of contraction) in low back pain patients, but they were also involved in both posture and respiration.

In their JOSPT study, Kolář and colleagues compared 29 healthy subjects (examined in an earlier study) with 18 patients suffering from chronic low back pain. They measured the excursion of different parts of the diaphragm during breathing using dynamic MRI, as well as the position of the diaphragm during inspiration and expiration. They also compared the excursion of the diaphragm while the subjects performed isometric flexion of the legs and arms (below). (Interestingly, the authors called this isometric flexion movement, a “postural activity.”)

They found that while diaphragm excursion and position were not different between controls and low back pain patients during resting breathing, the patients did exhibit reduced diaphragm movement with isometric contraction of the arms or legs, particularly in the anterior and middle portions, resulting in a steeper angle in the middle-posterior part of the diaphragm; this helps support Kolář’s representation of an inspiratory diaphragmatic posture.

Their findings are similar to the work of Paul Hodges and colleagues from Queensland, who examined the EMG activation and timing of the transverse abdominus and multifidus, pelvic floor, and diaphragm during arm and leg movements as well; however, the Australian testing was generally performed in standing and sitting in contrast to Kolář et al., who tested subjects in supine using dynamic MRI. I would have been very interested to see measurement of intraabominal pressure, as well as activation of the transverse abdominus and other core-stabilizing muscles concomitantly because of their coordinated efforts in posture and stabilization. As Dr. Stu McGill suggests, one muscle by itself cannot provide core stabilization. Kolář and colleagues also correctly noted this present study does not infer causation, and it can’t be determined if the diaphragm dysfunction is a cause or result of chronic low back pain.

The authors noted several limitations in their study, including a baseline difference in age and sex; however, they adjusted for these differences statistically by treating age as a covariate. Another possible issue not mentioned by the authors was the lack of intra-rater reliability and lack of blinding of the examiner. Finally, statistical power was not reported, nor were clinically meaningful differences. While these “statistical” limitations should not detract from the findings of this study, they should be considered when interpreting the results.

In summary, this study contributes to the body of knowledge supporting Kolář’s DNS approach and movement dysfunction in low back pain. As with any clinical research on patients, there are many variables that are difficult to control; nonetheless, these results offer some insight to the combined postural and respiratory function of the diaphragm. While this study is important in identifying the presence of diaphragm dysfunction, future research should investigate its etiology and successful interventions.

If you’re interested in taking DNS courses, I recommend my Assessment and Treatment of Muscle Imbalance: The Janda Approach co-authors and certified DNS instructors, Clare Frank or Robert Lardner. Listen to an interview by Clare for more information on DNS.

REFERENCE: Kolář P, et al. Postural function of the diaphragm in persons with and without chronic low back pain. J Orthop Sports Phys Ther. 2012;42(4):352-62. Epub 2011 Dec 21.


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