Cerebrovascular response during heavy upper body exercise: effect of mode of ventilation on blood flow velocity in the middle cerebral artery.

Heavy resistance exercise may be associated with a small risk of cerebral aneurysm rupture, subarachnoid hemorrhage, and symptoms of dizziness or outright weight-lifters' blackout, which may be induced by a rapid change in the cerebral blood flow. We hypothesized that these changes during heavy exercise could be associated with the mode of ventilation. The purpose of the present study was to elucidate the effect of the mode of ventilation on cerebral blood flow response during heavy upper body exercise. Subjects performed 15-s static exercises at 80% maximum voluntary contraction (MVC) under different modes of ventilation. In this study, we observed that heavy exercise with breath holding induced marked and rapid changes in the cerebral blood flow velocity in the middle cerebral artery during and after exercise as compared with that with continued normal ventilation. We also observed that hyperventilation before exercise could largely contribute to a lower cerebral blood flow velocity during exercise and which even extended to the recovery phase. Our data suggested that even during heavy upper body exercise, the mode of ventilation is very important for maintaining cerebral circulation.