In our previous study, we found that FetCO2 (PaCO2) increased during kendo with vocalization. Cerebral blood flow may increase during kendo exercises because PaCO2 has cerebral vasodilator effects. In this study, we measured the blood flow of the common carotid artery during intermittent bicycle ergometer exercise with vocalization as a basic study to elucidate the physiological characteristics of kendo. As a result, at the 80% V・O2peak with vocalization (same load as “kakari-keiko”), we observed a significant increase in FetCO2 (P = 0.022) and blood flow in the common carotid artery (P = 0.040). At the 60%V・O2peak with vocalization (same load as “kirikaeshi”), there was no significant increase in FetCO2; however, we observed a significant increase in blood flow in the common carotid artery (P = 0.035). In addition, in an ultrasonic image of the common jugular vein during exercise with vocalization, we observed the over-swelling of an internal jugular vein with partial blood regurgitation. This indicated that blood flow was temporarily stagnant. These results suggest that the increase in common carotid arteryblood flow was induced during exercise with vocalization. The increase in FetCO2 caused by vocalization, however, was not considered to be the main factor. One of the factors causing the increased common carotid artery blood flow was revealed to be related to an increasing-canceling of intrathoracic pressure due to vocalization-no-vocalization.
