Non-invasive NIR spectroscopy of human brain function during exercise

The assessment of physiological changes associated with brain activity has become possible by optical methods, such as near-infrared spectroscopy (NIRS). NIRS is a useful neuroimaging technique based on haemodynamic principles for the non-invasive investigation of brain in motion. Due to its properties, the near-infrared light can penetrate biological tissue reasonably well to assess brain activity and two types of measurements are possible according to the number of channels used: dynamic changes in a localized brain region or functional brain imaging. The theoretical and technological advances of the past 10–15 years have opened the door to a range of applications in the human movement sciences, including some that involve imaging of the adult brain during motor and cognitive tasks, which for many years had been inaccessible to NIRS. This article examines the perturbation methods for measuring cerebral haemodynamic responses within resting and exercise conditions in humans and how NIRS can be used to image the moving brain. Methodological challenges of NIRS technique are presented, while the advantages and pitfalls of NIRS compared to other neuroimaging methods are discussed. Actual and future uses for NIRS in the field of sport sciences are outlined for a better understanding of brain processes during movement.