Cerebral cortex activity during supramaximal exhaustive exercise

Aim. The purpose of this study was to examine the effect of fatigue resulting from supramaximal dynamic exercise on cerebral cortex activity. Methods. Five healthy male subjects (age 24.6±0.4 years, body weight 62.9±1.1 kg, height 175.3±1.2 cm, and maximal O₂ uptake per body mass 48.4±1.3 ml/kg/min) participated in this study. All subjects performed at 120% of maximal oxygen uptake (VO₂peak) on a cycle ergometer until reaching a state of volitional fatigue. Cerebral oxygenation was measured by near-infrared spectroscopy (NIRS) throughout the supramaximal constant exhaustive exercise. Results. The mean exercise duration of the subjects was 147.2±3.4 s. The peak value of blood lactate concentration within 3-10 min after the exercise test was 14.4±0.1 mmol/l. Cerebral oxygenation (8.8±1.8 μmol/l) was increased significantly during the first minutes of exercise compared with the pre-exercise value (p<0.05) and cerebral oxygenation decreased with the passage of time during exercise. Cerebral oxygenation at the end of exercise decreased significantly compared with the resting value (-29.±3.4 μmol/l, p<0.05). Conclusion. These findings suggest that the exhaustive exercise induces the decrease of cerebral function and that the fatigue resulting from dynamic exercise decreases the cerebral cortex activity.