Middle cerebral artery flow velocity and pulse pressure during dynamic exercise in humans.

Exercise challenges cerebral autoregulation (CA) by a large increase in pulse pressure (PP) that may make systolic pressure exceed what is normally considered the upper range of CA. This study examined the relationship between systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP) and systolic (V(s)), diastolic (V(d)). and mean (V(m)) middle cerebral artery (MCA) blood flow velocity during mild, moderate, and heavy cycling exercise. Dynamic CA and steady-state changes in MCA V in relation to changes in arterial pressure were evaluated using transfer function analysis. PP increased by 37% and 57% during moderate and heavy exercise, respectively (P < 0.05), and the pulsatility of MCA V increased markedly. Thus exercise increased MCA V(m) and V(s) (P < 0.05) but tended to decrease MCA V(d) (P = 0.06). However, the normalized low-frequency transfer function gain between MAP and MCA V(m) and between SBP and MCA V(s) remained unchanged from rest to exercise, whereas that between DBP and MCA V(d) increased from rest to heavy exercise (P < 0.05). These findings suggest that during exercise, CA is challenged by a rapid decrease rather than by a rapid increase in blood pressure. However, dynamic CA remains able to modulate blood flow around the exercise-induced increase in MCA V(m), even during high-intensity exercise.

[1]  R. Bondar,et al.  Vertical shift in cerebral autoregulation curve: a graded head-up tilt study. , 1999, Canadian aeronautics and space journal. Le journal aeronautique et spatial du Canada.

[2]  P. Berlit,et al.  Phase relationship between cerebral blood flow velocity and blood pressure. A clinical test of autoregulation. , 1995, Stroke.

[3]  Rong Zhang,et al.  Cerebral Hemodynamics During the Valsalva Maneuver: Insights From Ganglionic Blockade , 2004, Stroke.

[4]  R. Panerai,et al.  Linear and nonlinear analysis of human dynamic cerebral autoregulation. , 1999, American journal of physiology. Heart and circulatory physiology.

[5]  B. Levine,et al.  Effects of head-down-tilt bed rest on cerebral hemodynamics during orthostatic stress. , 1997, Journal of applied physiology.

[6]  R. Aaslid,et al.  Cerebral autoregulation dynamics in humans. , 1989, Stroke.

[7]  Takuya Osada,et al.  Brain and central haemodynamics and oxygenation during maximal exercise in humans , 2004, The Journal of physiology.

[8]  J. Sinclair,et al.  Weight-lifters' blackout. , 1973, Lancet.

[9]  N. Secher,et al.  Middle cerebral artery blood velocity during rowing. , 1997, Acta physiologica Scandinavica.

[10]  J. East,et al.  Middle cerebral artery blood flow velocity in elite power athletes during maximal weight-lifting , 2000, Neurological research.

[11]  A Villringer,et al.  Assessment of blood flow velocity and diameter of the middle cerebral artery during the acetazolamide provocation test by use of transcranial Doppler sonography and MR imaging. , 2000, AJNR. American journal of neuroradiology.

[12]  J Van Goudoever,et al.  Continuous stroke volume monitoring by modelling flow from non-invasive measurement of arterial pressure in humans under orthostatic stress. , 1999, Clinical science.

[13]  B. Whipp.  The slow component of O2 uptake kinetics during heavy exercise. , 1994, Medicine and science in sports and exercise.

[14]  O B Paulson,et al.  Cerebral autoregulation. , 1984, Stroke.

[15]  B. Levine,et al.  Transfer function analysis of dynamic cerebral autoregulation in humans. , 1998, American journal of physiology. Heart and circulatory physiology.

[16]  N. Secher,et al.  Cerebral carbohydrate cost of physical exertion in humans. , 2004, American journal of physiology. Regulatory, integrative and comparative physiology.

[17]  Cole A. Giller,et al.  Cerebral Versus Systemic Hemodynamics During Graded Orthostatic Stress in Humans , 1994, Circulation.

[18]  N. Lassen,et al.  Middle cerebral artery blood velocity and plasma catecholamines during exercise. , 1996, Acta physiologica Scandinavica.

[19]  R. Hughson,et al.  Cerebral hemodynamics and resistance exercise. , 2002, Medicine and science in sports and exercise.

[20]  B K Rutt,et al.  MRI measures of middle cerebral artery diameter in conscious humans during simulated orthostasis. , 2000, Stroke.

[21]  B. Levine,et al.  Deterioration of cerebral autoregulation during orthostatic stress: insights from the frequency domain. , 1998, Journal of applied physiology.

[22]  N. Secher,et al.  Middle cerebral artery blood velocity depends on cardiac output during exercise with a large muscle mass. , 1998, Acta physiologica Scandinavica.

[23]  L. Rowell.  Human Cardiovascular Control , 1993 .

[24]  B. Levine,et al.  Autonomic Neural Control of Dynamic Cerebral Autoregulation in Humans , 2002, Circulation.

[25]  C A Giller.  The frequency-dependent behavior of cerebral autoregulation. , 1990, Neurosurgery.

[26]  N. Secher,et al.  Cerebral metabolism during upper and lower body exercise. , 2004, Journal of applied physiology.

[27]  M. Brys,et al.  Dynamic cerebral autoregulation remains stable during physical challenge in healthy persons. , 2003, American journal of physiology. Heart and circulatory physiology.