Cerebral blood flow during static exercise in humans

Rogers, H. B.; Schroeder, Torben V; Secher, Niels H.; Mitchell, Jere H.

doi:10.1152/jappl.1990.68.6.2358

Cited by 34 publications

(25 citation statements)

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“…The fact that V mean is maintained during postexercise muscle ischemia, although sympathetic activity increases markedly, supports the theory that MCA V mean is not influenced by sympathetic activity under physiological circumstances (82). The steadiness of both the 133 Xe clearancedetermined CBF and MCA V mean during static exercise in the face of an increase in MAP similar to what is found during dynamic exercise (49,89) is another indication that it is not the increase in MAP per se that influences CBF. It should be noted that owing to the latency of cerebral autoregulation mechanisms, it takes ϳ3-5 s to offset the effects of changes in MAP (46) and with rapid fluctuations in MAP in response to, e.g., posture change (102), weight lifting (58), and rowing (81), MCA V mean changes in parallel.…”

Section: Regulation Of Cbf During Exercisesupporting

confidence: 57%

Cerebral blood flow and metabolism during exercise: implications for fatigue

Secher¹,

Seifert²,

Lieshout³

2008

Journal of Applied Physiology

294

281

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Secher NH, Seifert T, Van Lieshout JJ. Cerebral blood flow and metabolism during exercise, implications for fatigue. J Appl Physiol 104: 306 -314, 2008. First published October 25, 2007 doi:10.1152/japplphysiol.00853.2007.-During exercise: the Kety-Schmidt-determined cerebral blood flow (CBF) does not change because the jugular vein is collapsed in the upright position. In contrast, when CBF is evaluated by 133 Xe clearance, by flow in the internal carotid artery, or by flow velocity in basal cerebral arteries, a ϳ25% increase is detected with a parallel increase in metabolism. During activation, an increase in cerebral O 2 supply is required because there is no capillary recruitment within the brain and increased metabolism becomes dependent on an enhanced gradient for oxygen diffusion. During maximal whole body exercise, however, cerebral oxygenation decreases because of eventual arterial desaturation and marked hyperventilation-related hypocapnia of consequence for CBF. Reduced cerebral oxygenation affects recruitment of motor units, and supplemental O 2 enhances cerebral oxygenation and work capacity without effects on muscle oxygenation. Also, the work of breathing and the increasing temperature of the brain during exercise are of importance for the development of so-called central fatigue. During prolonged exercise, the perceived exertion is related to accumulation of ammonia in the brain, and data support the theory that glycogen depletion in astrocytes limits the ability of the brain to accelerate its metabolism during activation. The release of interleukin-6 from the brain when exercise is prolonged may represent a signaling pathway in matching the metabolic response of the brain. Preliminary data suggest a coupling between the circulatory and metabolic perturbations in the brain during strenuous exercise and the ability of the brain to access slow-twitch muscle fiber populations. ammonium; central fatigue; cerebral blood flow; cerebral metabolic ratio; glucose; glycogen; lactate; oxygen; temperature DURING EXERCISE, THERE IS hyperbolic relationship between work intensity and endurance, and A. V. Hill used the relationship to demonstrate that energy turnover can be taken to represent a continuous provision of energy supplemented by an energy store (56). Yet, it is the brain that makes the decision when to slow down or to stop exercise, and from that perspective fatigue is of central origin. Obviously, cerebral metabolism becomes affected if exercise has a duration that lowers blood glucose (74), and, equally, the low O 2 tension faced during mountaineering (47) affects brain function. Perturbation of cerebral metabolism is, however, not restricted to situations where the arterial glucose and O 2 levels are reduced. Recent investigations (3,65,70,90) indicate that also at sea level maximal exercise may be associated with so-called central fatigue as indicated by lower voluntary activation than the force elicited during evoked contractions.The purpose of this review is to address cerebral metabolism in ...

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Section: Regulation Of Cbf During Exercisesupporting

confidence: 57%

Cerebral blood flow and metabolism during exercise: implications for fatigue

Secher¹,

Seifert²,

Lieshout³

2008

Journal of Applied Physiology

294

281

View full text Add to dashboard Cite

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“…Results from other studies support this conclusion. Data show that middle cerebral artery blood velocity remains constant as blood pressure rises during isometric exercise 17. On the contrary, ophthalmic artery blood velocity increases significantly during similar conditions 18.…”

Section: Discussionmentioning

confidence: 82%

Glaucoma patients demonstrate faulty autoregulation of ocular blood flow during posture change

Evans

Harris

Garrett

et al. 1999

British Journal of Ophthalmology

108

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“…In contrast to studies in which the TCD-determined MCA V mean or cerebral blood flow was determined intermittently during static exercise (16,29) or focused on the depression established during a maximal lift (7), we took advantage of the ability of the Doppler technique to record beat-by-beat MCA V mean . We hypothesized that MCA V mean would be influenced by the steep increase in MAP at the onset of static exercise and that its time course would be affected by changes in both CVP and the arterial carbon dioxide tension (Pa CO 2 ).…”

mentioning

confidence: 99%

Middle cerebral artery blood velocity during intense static exercise is dominated by a Valsalva maneuver

Pott

Lieshout

Ide³

et al. 2003

Journal of Applied Physiology

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Lifting of a heavy weight may lead to "blackout" and occasionally also to cerebral hemorrhage, indicating pronounced consequences for the blood flow through the brain. We hypothesized that especially strenuous respiratory straining (a Valsalva-like maneuver) associated with intense static exercise would lead to a precipitous rise in mean arterial and central venous pressures and, in turn, influence the middle cerebral artery blood velocity (MCA V(mean)) as a noninvasive indicator of changes in cerebral blood flow. In 10 healthy subjects, MCA V(mean) was evaluated in response to maximal static two-legged exercise performed either with a concomitantly performed Valsalva maneuver or with continued ventilation and also during a Valsalva maneuver without associated exercise (n = 6). During static two-legged exercise, the largest rise for mean arterial pressure and MCA V(mean) was established at the onset of exercise performed with a Valsalva-like maneuver (by 42 +/- 5 mmHg and 31 +/- 3% vs. 22 +/- 6 mmHg and 25 +/- 6% with continued ventilation; P < 0.05). Profound reductions in MCA V(mean) were observed both after exercise with continued ventilation (-29 +/- 4% together with a reduction in the arterial CO(2) tension by -5 +/- 1 Torr) and during the maintained Valsalva maneuver (-21 +/- 3% together with an elevation in central venous pressure to 40 +/- 7 mmHg). Responses to performance of the Valsalva maneuver with and without exercise were similar, reflecting the deterministic importance of the Valsalva maneuver for the central and cerebral hemodynamic response to intense static exercise. Continued ventilation during intense static exercise may limit the initial rise in arterial pressure and may in turn reduce the risk of hemorrhage. On the other hand, blackout during and after intense static exercise may reflect a reduction in cerebral blood flow due to expiratory straining and/or hyperventilation.

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Cerebral blood flow during static exercise in humans

Cited by 34 publications

References 0 publications

Cerebral blood flow and metabolism during exercise: implications for fatigue

Cerebral blood flow and metabolism during exercise: implications for fatigue

Glaucoma patients demonstrate faulty autoregulation of ocular blood flow during posture change

Middle cerebral artery blood velocity during intense static exercise is dominated by a Valsalva maneuver

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