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Does cerebral blood flow & oxygenation limit maximal exercise performance in healthy humans?
Author(s) -
Louvaris Zafeiris,
VOGIATZIS IOANNIS,
DIMITRIS ATHANASOPOULOS,
VASILIS ANDRIANOPOULOS,
PANAGIOTIS ALEXOPOULOS,
HARRIETH WAGNER,
HABAZETTL HELMUT,
ROUSSOS CHARIS,
WAGNER PETER,
ZAKYNTHINOS SPYROS
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.lb643
Subject(s) - oxygenation , cerebral blood flow , hypoxia (environmental) , medicine , incremental exercise , blood flow , vo2 max , perfusion , chemistry , hemoglobin , oxygen , anesthesia , endocrinology , cardiology , heart rate , blood pressure , organic chemistry
Recent reports suggest that changes in cerebral oxygenation may play a pivotal role in limiting maximal exercise capacity in humans. We investigated whether a critical change in cerebral oxygen blood flow and oxygenation may occur from modest to supra‐maximal exercise in hypoxia compared to normoxia. Cerebral blood perfusion was measured by near infrared spectroscopy using indocyanine green dye in 11 cyclists during an incremental discontinuous protocol to the limit of tolerance. During both normoxic and hypoxic (FIO2: 0.12) conditions brain blood flow significantly increased reaching identical levels, at maximal (42±5 versus 42±2 ml/min/100g) and supra‐maximal (40±5 versus 40±4 ml/min/100g) exercise. Deoxy‐hemoglobin concentration (deoxy‐Hb: an index of oxygen extraction) was greater in hypoxia compared to normoxia at maximal (13.1±1.3 vs. 2.3±0.5 μmol/L) and supra‐maximal (11.9±1.5 vs. 2.5±0.5 μmol/L) exercise. Neither in hypoxia nor in normoxia deoxy‐Hb changed significantly from modest (60% max) to supra‐maximal exercise (13.8±1.6 vs. 11.9±1.5 and 1.0±1.5 versus 2.5±0.5 μmol/L, respectively). Importantly, supra‐maximal normoxic deoxy‐Hb (2.5±0.5 μmol/L) was lower than that recorded at 60% max exercise (13.8±1.6 μmol/L) in hypoxia. Cerebral blood flow and oxygenation do not appear to be the signals that terminate exercise in humans.