scholarly journals Cerebral Metabolism is Influenced by Muscle Ischaemia During Exercise in Humans

2003 ◽  
Vol 88 (2) ◽  
pp. 297-302 ◽  
Author(s):  
Mads K. Dalsgaard ◽  
Lars Nybo ◽  
Yan Cai ◽  
Niels H. Secher
Keyword(s):  
Cerebral Metabolism ◽  
Muscle Ischaemia ◽  
Exercise In Humans

Effects of hyperthermia on cerebral blood flow and metabolism during prolonged exercise in humans

2002 ◽  
Vol 93 (1) ◽  
pp. 58-64 ◽  
Author(s):  
Lars Nybo ◽  
Kirsten Møller ◽  
Stefanos Volianitis ◽  
Bodil Nielsen ◽  
Niels H. Secher
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Metabolic Rate ◽  
Core Temperature ◽  
Prolonged Exercise ◽  
Cerebral Metabolism ◽  
Cycle Ergometer ◽  
Carbon Dioxide Tension ◽  
Cerebral Metabolic Rate ◽  
Exercise In Humans

The development of hyperthermia during prolonged exercise in humans is associated with various changes in the brain, but it is not known whether the cerebral metabolism or the global cerebral blood flow (gCBF) is affected. Eight endurance-trained subjects completed two exercise bouts on a cycle ergometer. The gCBF and cerebral metabolic rates of oxygen, glucose, and lactate were determined with the Kety-Schmidt technique after 15 min of exercise when core temperature was similar across trials, and at the end of exercise, either when subjects remained normothermic (core temperature = 37.9°C; control) or when severe hyperthermia had developed (core temperature = 39.5°C; hyperthermia). The gCBF was similar after 15 min in the two trials, and it remained stable throughout control. In contrast, during hyperthermia gCBF decreased by 18% and was therefore lower in hyperthermia compared with control at the end of exercise (43 ± 4 vs. 51 ± 4 ml · 100 g−1· min−1; P < 0.05). Concomitant with the reduction in gCBF, there was a proportionally larger increase in the arteriovenous differences for oxygen and glucose, and the cerebral metabolic rate was therefore higher at the end of the hyperthermic trial compared with control. The hyperthermia-induced lowering of gCBF did not alter cerebral lactate release. The hyperthermia-induced reduction in exercise cerebral blood flow seems to relate to a concomitant 18% lowering of arterial carbon dioxide tension, whereas the higher cerebral metabolic rate of oxygen may be ascribed to a Q10(temperature) effect and/or the level of cerebral neuronal activity associated with increased exertion.

2D NMR studies on muscle and cerebral metabolism in vivo

1994 ◽  
Vol 91 ◽  
pp. 697-703 ◽  
Author(s):  
B Gillet ◽  
BT Doan ◽  
C Verre-Sebrie ◽  
O Fedeli ◽  
JC Beloeil ◽  
...  
Keyword(s):  
Cerebral Metabolism ◽  
2D Nmr ◽  
Nmr Studies

Oronasal partitioning of ventilation during exercise in humans

1991 ◽  
Vol 71 (2) ◽  
pp. 546-551 ◽  
Author(s):  
J. R. Wheatley ◽  
T. C. Amis ◽  
L. A. Engel
Keyword(s):  
Upper Airway ◽  
Normal Subjects ◽  
Face Mask ◽  
Inspiratory Flow ◽  
Mean Flow ◽  
Total Flow ◽  
Progressive Exercise ◽  
Expiratory Flow ◽  
Exercise In Humans

The partitioning of oronasal breathing was studied in five normal subjects during progressive exercise. Subjects performed three to five identical runs, each consisting of four 1-min work periods at increments of 50 W. Nasal and oral airflow were measured simultaneously using a partitioned face mask both during and for 4 min after exercise. Total mean flows were the sum of nasal and oral flows. At a total mean inspiratory flow of 2 l/s, the nasal fraction of total flow was 0.36 +/- 0.04 (SE) and decreased by 6 +/- 3% between total flows of 1.5 and 2.5 l/s. Throughout exercise, the nasal fraction of total mean inspiratory flow did not differ from that of total expiratory flow and was similar to that of total mean inspiratory flow during the postexercise period at a corresponding total mean flow (both P greater than 0.02). The results show that oronasal flow partitioning is not directly due to the exercise itself but is related to the level of ventilation and is uninfluenced by the direction of upper airway flow (i.e., inspiratory vs. expiratory). These findings suggest tightly controlled modulation of the relative resistances of the oral and/or nasal pathways.

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