[Effects of active and passive movement stimuli on cerebral hemodynamics and the cerebral metabolism]

In contrast to the well-examined cardiovascular changes during movement stimuli, up to now changes of cerebral hemodynamics and cerebral metabolism have rarely been studied. We investigated the question if active and passive movement stimuli cause changes in the cerebral hemodynamics and the cerebral metabolism.

Active and passive repetitive movement stimuli on 14 volunteers (8 females, 6 males, age 35 +/- 8 years) were examined. As a parameter of cerebral hemodynamics the mean and the peak blood flow velocity (mCBFV(MCA), pCBFV(MCA)) in the middle cerebral artery (MCA) were recorded by transcranial Doppler sonography. At the same time the noninvasive blood pressure (Penaz method) and the CO(2) expiration concentration were investigated on 8 volunteers of the collective. As cerebral metabolic parameters we examined in 4 volunteers additionally the cerebral respiratory chain enzyme cytochrome aa3 (ccytaa3) and the cerebral oxygen saturation (cHbO(2)) by the transcranial near infrared spectroscopy. With each volunteer 4 measurement series were carried out with a special active and passive exercise program for the right upper as well as the right lower extremity. Each measurement series was formed according to the evoked flow test (R. Aaslid): Exercises were carried out for 20 s, followed by a break of 20 s; this was repeated 10 times for each series.

During active exercises of the right lower extremity we found an increase of 13.6% (p < 0.001) of pCBFV(MCA) and an increase of 3.8% (p = 0.003) of mCBFV(MCA). During passive exercises of the lower extremity the increases ran up to 12.3% (p < 0.001) for pCBFV(MCA) and 3.4% (p = 0.004) for mCBFV(MCA). The increases of pCBFV(MCA) came up to 12.5% (p < 0.001) at active exercises of the right upper extremity, those of mCBFV(MCA) to 3.5% (p = 0.15). During passive exercises of the upper extremity the pCBFV(MCA) increased by 12.2% (p < 0.001) and the mCBFV(MCA) by 4.6% (p = 0.007). Significant increases of ccytaa3 were measured during active exercises of the upper extremity (1.6%; p = 0.04) and of the lower extremity (2.7%, p = 0.007). We also found an increase of ccytaa3 during passive exercises of the upper extremity (1.5%, p = 0.04). Significant changes of cHbO(2) were measured with 2.5% (p < 0.05) at active exercises of the lower extremity.

These studies show that active as well as passive clinical exercises cause an increase of cerebral blood flow velocity. We attribute the increase of cerebral hemodynamics and cerebral metabolism to cerebral activation and autoregulative mechanisms.