Contraction of the human diaphragm during rapid postural adjustments

Abstract

The response of the diaphragm to the postural perturbation produced by rapid flexion of the shoulder to a visual stimulus was evaluated in standing subjects. Gastric, oesophageal and transdiaphragmatic pressures were measured together with intramuscular and oesophageal recordings of electromyographic activity (EMG) in the diaphragm. To assess the mechanics of contraction of the diaphragm, dynamic changes in the length of the diaphragm were measured with ultrasonography. With rapid flexion of the shoulder in response to a visual stimulus, EMG activity in the costal and crural diaphragm occurred about 20 ms prior to the onset of deltoid EMG. This anticipatory contraction occurred irrespective of the phase of respiration in which arm movement began. The onset of diaphragm EMG coincided with that of transverses abdominis. Gastric and transdiaphragmatic pressures increased in association with the rapid arm flexion by 13.8 ± 1.9 (mean ±s.e.m.) and 13.5 ± 1.8 cmH2O, respectively. The increases occurred 49 ± 4 ms after the onset of diaphragm EMG, but preceded the onset of movement of the limb by 63 ± 7 ms. Ultrasonographic measurements revealed that the costal diaphragm shortened and then lengthened progressively during the increase in transdiaphragmatic pressure. This study provides definitive evidence that the human diaphragm is involved in the control of postural stability during sudden voluntary movement of the limbs.

Network of Breathing. Multifunctional Role of the Diaphragm: A Review

“…The diaphragm EMG activity was associated with an increase of transdiaphragmatic pressure. Ultrasonographic measurements also revealed that the costal diaphragm shortened and then lengthened progressively during the increase in transdiaphragmatic pressure [28]. Next studies conducted by Hodges have provided further confirmation of this function.…”

“…The diaphragm cannot move the trunk voluntary, but its contraction contributes to trunk (spinal) stability via an increase of pressure in the abdominal cavity. This dual function of the diaphragm (ventilation and posture) is performed simultaneously [27][28][29].…”

Comparing routine neurorehabilitation program with trunk exercises based on Bobath concept in multiple sclerosis: Pilot study

“…Static sitting balance improved significantly in the control group only. This could be explained by the important role of the trunk in stabilization and intended limb movements [30][31][32].…”

Postural Function of the Diaphragm in Persons With and Without Chronic Low Back Pain

“…9 In turn, the function of the diaphragm may affect how the trunk is stabilized, especially during postural activity. 11,15,22 Various studies have shown that the pelvic girdle and lumbar spine are reflexively stabilized and braced prior to the initiation of extremity movements. 3,13,17,22 The central nervous system must be able to anticipate movement and stabilize the entire core musculature automatically to provide a stable base from which the muscles performing the movement can pull.…”