Cerebral oxygenation during intermittent supramaximal exercise

This study examined cerebral deoxygenation during intermittent supramaximal exercise in six healthy male subjects (age: 27.2±0.6 years (mean±S.E.)). The subjects performed seven times exercise at an intensity corresponding to 150% of maximal oxygen uptake (V̇_O2max) on cycle ergometer (30 s exercise/15 s rest). Cerebral oxygenation was measured by near-infrared spectroscopy (NIRS). The peak blood lactate concentration after exercise was 15.3±0.2 mmol/l. Cerebral oxygenation increased in first repetition compared with at rest (+5.7±0.6 μM; P<0.05), but then decreased with time. Thus, in the last repetition cerebral oxygenation was -8.5±0.4 μM (P<0.05). There was no significant change in arterial oxygen saturation (99.6±0.1 at rest, 98.4±0.2 at the final set of intermittent exercise), and there was no correlated change in end-tidal CO ₂ concentration with cerebral oxygenation (P>0.05). These findings suggest that the fatigue resulting from dynamic severe exercise related to a decrease in the cerebral oxygenation level.