Fast MRI used to evaluate the effect of abdominal belts during contraction of trunk muscles.
METHODS
This study focused on the effects that abdominal belts have on the sagittal section of the abdominal and pelvic cavity during contraction of the trunk muscles. Fast magnetic resonance imaging was used during the Valsalva maneuver by 11 healthy men.


OBJECTIVE
To evaluate the effect of an abdominal belt on the geometric changes in the sagittal section during Valsalva maneuvers.


BACKGROUND
Several hypotheses about the effect of an abdominal belt have considered intraabdominal pressure, which has a hydraulic effect on the diaphragm, providing stability to the spine. However, there is little information on changes in the sagittal section of the abdominal and pelvic cavity.


METHODS
Eleven male volunteers without back problems were studied with fast magnetic resonance images. Sagittal section images of the abdominal and pelvic cavity were obtained under six conditions: without the belt at rest, at full inhalation, and at full inhalation with Valsalva, as well as with the belt at rest, at full inhalation, and at full inhalation with Valsalva.


RESULTS
When the belt was worn, the sagittal section area of the abdominal and pelvic cavity did not change, but its shape did. Also, the anteroposterior diameter of the abdominal and pelvic cavity increased at its upper part and decreased at its middle part, elevating the liver and diaphragm. Additionally, the lever arm length of the intraabdominal pressure increased significantly.


CONCLUSIONS
Fast magnetic resonance imaging quantified the effect of an abdominal belt on the abdominal geometric changes during the Valsalva maneuvers with the patient in a supine position.
Department of Orthopaedic Surgery, Gifu University School of Medicine, Department of Orthopaedic Surgery, Takayama Red Cross Hospital, Gifu, Japan. kei@gix.or.jp
Kei
K
Miyamoto
Katsuji
K
Shimizu
Kazuaki
K
Masuda
D000005:Abdomen / Q000033:anatomy & histology / Q000502:physiology*; D000328:Adult; D003964:Diaphragm / Q000033:anatomy & histology; D006801:Humans; D008099:Liver / Q000033:anatomy & histology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology*; D010388:Pelvis / Q000033:anatomy & histology; D010529:Peritoneal Cavity / Q000033:anatomy & histology / Q000502:physiology; D011482:Protective Devices; D012016:Reference Values; D012119:Respiration; D013131:Spine / Q000033:anatomy & histology; D016683:Supine Position / Q000502:physiology; D014636:Valsalva Maneuver / Q000502:physiology