Aerobic fitness influences cerebral oxygenation response to maximal exercise in healthy subjects

The study examined whether the aerobic fitness level modifies the cerebral oxygenation response to incremental ramp exercise, and more specifically the decline in cerebral oxygenation from heavy exercise up to maximal intensities. 11 untrained ((V)over dot O-2max 47.3 +/- 4.0 mL min(-1) kg(-1)) and 13 endurance-trained ((V)over dot 2(max) 61.2 +/- 8.0 mL min(-1) kg(-1)) healthy men performed a maximal ramp cycle exercise. Left prefrontal cortex oxygenation (Delta HbO(2)) was monitored by near-infrared spectroscopy. A cerebral oxygenation threshold decline (Th-COx) during exercise was determined. Tha(Cox) occurred in all subjects but for higher (V)over dot O-2 (mL min(-1) kg(-1)) in endurance-trained than in untrained subjects (P < 0.01). At submaximal exercise intensity corresponding to Th-COx, Delta HbO(2) was higher in endurance-trained than in untrained subjects (P<0.05). (V) over dot O-2 at Th-COx was related to (V)over dot(O2) at respiratory compensation point (n =24, r=0.93, P<0.001) and to (V)over dot O-2max (n = 24, r = 0.92, P < 0.001). These findings indicate that above the respiratory compensation point the prefrontal O-2 demand exceeds the supply in untrained and in endurance-trained subjects. In addition, the occurrence of Th-COx was delayed to higher absolute exercise intensities in endurance-trained in relation with their higher (V)over dot(O2max) than untrained men. These results demonstrated that aerobic fitness influences cerebral oxygenation during exercise. (C) 2014 Elsevier B.V. All rights reserved.