Cerebral oxygenation and metabolism during exercise following three months of endurance training in healthy overweight males

Abstract

Endurance training improves muscular and cardiovascular fitness, but the effect on cerebral oxygenation and metabolism remains unknown. We hypothesized that 3 mo of endurance training would reduce cerebral carbohydrate uptake with maintained cerebral oxygenation during submaximal exercise. Healthy overweight males were included in a randomized, controlled study (training: n = 10; control: n = 7). Arterial and internal jugular venous catheterization was used to determine concentration differences for oxygen, glucose, and lactate across the brain and the oxygen-carbohydrate index [molar uptake of oxygen/(glucose + ½ lactate); OCI], changes in mitochondrial oxygen tension (ΔPMitoO2) and the cerebral metabolic rate of oxygen (CMRO2) were calculated. For all subjects, resting OCI was higher at the 3-mo follow-up (6.3 ± 1.3 compared with 4.7 ± 0.9 at baseline, mean ± SD; P < 0.05) and coincided with a lower plasma epinephrine concentration ( P < 0.05). Cerebral adaptations to endurance training manifested when exercising at 70% of maximal oxygen uptake (∼211 W). Before training, both OCI (3.9 ± 0.9) and ΔPMitoO2(−22 mmHg) decreased ( P < 0.05), whereas CMRO2increased by 79 ± 53 micromol·100·g−1min−1( P < 0.05). At the 3-mo follow-up, OCI (4.9 ± 1.0) and ΔPMitoO2(−7 ± 13 mmHg) did not decrease significantly from rest and when compared with values before training ( P < 0.05), CMRO2did not increase. This study demonstrates that endurance training attenuates the cerebral metabolic response to submaximal exercise, as reflected in a lower carbohydrate uptake and maintaind cerebral oxygenation.