1 3 Eur J Appl Physiol DOI 10.1007/s00421-015-3199-4 ORIGINAL ARTICLE The relationship between exercise intensity, cerebral oxygenation and cognitive performance in young adults Saïd Mekari 1,2 · Sarah Fraser 1,3 · Laurent Bosquet 1,2,4 · Clément Bonnéry 1,5 · Véronique Labelle 1,3 · Philippe Pouliot 5,6 · Frédéric Lesage 5,6 · Louis Bherer 1,7 Received: 11 September 2014 / Accepted: 30 May 2015 © Springer-Verlag Berlin Heidelberg 2015 was monitored during the resting and exercise conditions over the prefrontal cortex (PFC) using near-infrared spec- troscopy (NIRS). Results High-intensity exercise slowed RT in both the Naming (p = 0.04) and the Executive condition (p = 0.04). The analysis also revealed that high-intensity exercise was associated with a decreased accuracy when compared to low-intensity exercise (p = 0.021). Neuroimaging results confirm a decrease of cerebral oxygenation during high- intensity exercise in comparison to low- (p = 0.004) and moderate-intensity exercise (p = 0.003). Correlations revealed that a lower cerebral HbO 2 in the prefrontal cortex was associated with slower RT in the Executive condition only (p = 0.04, g = -0.72). Conclusion Results of the present study suggest that low to moderate exercise intensity does not alter Executive functioning, but that exercise impairs cognitive functions (Executive and non-Executive) when the physical work- load becomes heavy. The cerebral HbO 2 correlation sug- gests that a lower availability of HbO 2 was associated with slower RT in the Executive condition only. Keywords Reaction time · Near-infrared spectroscopy · Cerebral HbO 2 · Peak power output · Hyperventilation Abbreviations ANOVA Analysis of variance BMI Body mass index C0 2 Carbon dioxide CBF Cerebral blood flow CBF Cerebral blood flow fNIRS Functional near-infrared spectroscopy GLM General linear model HbO Oxy-hemoglobin HbR Deoxy-hemoglobin Abstract Purpose To assess the relationship between exercise intensity, cerebral HbO 2 and cognitive performance (Exec- utive and non-Executive) in young adults. Methods We measured reaction time (RT) and accuracy, during a computerized Stroop task, in 19 young adults (7 males and 12 females). Their mean ± SD age, height, body mass and body mass index (BMI) were 24 ± 4 years, 1.67 ± 0.07 m, 72 ± 14 kg and 25 ± 3 kg m -2 , respec- tively. Each subject performed the Stroop task at rest and during cycling at exercise of low intensity [40 % of peak power output (PPO)], moderate intensity (60 % of PPO) and high intensity (85 % of PPO). Cerebral oxygenation Communicated by Toshio Moritani. * Saïd Mekari said.mekary@gmail.com 1 Centre de Recherche, Institut Universitaire de Gériatrie de Montréal, Laboratoire LESCA, 4565, Chemin Queen-Mary, Montréal H3W 1W5, QC, Canada 2 Département de Kinésiologie, Université de Montréal, CP 6128, succ. Centre-ville, Montréal H3C 3J7, QC, Canada 3 Département de Psychologie, Université de Québec à Montreal, C.P. 8888 succ. Centre-ville, Montréal H3C 3P8, QC, Canada 4 Faculté des Sciences du Sport, Laboratoire MOVE (EA 6314), Université de Poitiers, 8, allée Jean Monnet, 86000 Poitiers, France 5 Département de Génie Biomédical, École Polytechnique, CP 6079, succ. Centre-ville, Montréal H3C 3A7, QC, Canada 6 Centre de recherche, Institut de Cardiologie de Montréal, 5000, rue Bélanger, Montréal H1T 1C8, QC, Canada 7 PERFORM Centre, Concordia University, 7200 Sherbrooke St. W., Montreal, QC H4B 1R6, Canada