Saeed Changizi Ashtiani, Saeed Khameneh , Nahid Ghandechilar,
Volume 5, Issue 2 (Summer 2002)
Abstract
Introduction: The off response of baroreflex is mostly ignored by recent studies. In the present study we aimed at assessing this during rest, and isometric and dynamic exercise.
Materials and Methods: 12 young male subjects volunteered the study. Using an Eckberg neck suction device each subject received a brief (10 sec). about of sustained stimulus with -50 mm Hg pressure in the neck chamber. The workload incorporated was 100w for dynamic and 50% of maximal effort for isometric exercise. Electrocardiogram was recorded on line R-R intervals were assessed beat and responsed cardiac response. This was significant at all three states.
Results: on the average, the peak off-response tachycardia occurred earlier (3rd sec). in exercise tests as compared with that of rest (5th sec). the intensity of tachycardia was more prominent at rest, isometric exercise, and dynamic exercise, respectively and the difference between rest and dynamic exercise gained significance (p<0.01).
Conclusion: The attenuation of so called post vagal tachycardia during exercise is in accordance with the assumed reduction of vagal tone during exercise.
