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Functional near-infrared spectroscopy (fNIRS) provides an alternative to functional magnetic resonance imaging (fMRI) for assessing changes in cortical hemodynamics. To establish the utility of fNIRS for measuring differential recruitment of the motor network during the production of timing-based actions, we measured cortical hemodynamic responses in 10 healthy adults while they performed two versions of a finger-tapping task. The task, used in an earlier fMRI study (Jantzen et al., 2004), was designed to track the neural basis of different timing behaviors. Participants paced their tapping to a metronomic tone, then continued tapping at the established pace without the tone. Initial tapping was either synchronous or syncopated relative to the tone. This produced a 2 × 2 design: synchronous or syncopated tapping and pacing the tapping with or continuing without a tone. Accuracy of the timing of tapping was tracked while cortical hemodynamics were monitored using fNIRS. Hemodynamic responses were computed by canonical statistical analysis across trials in each of the four conditions. Task-induced brain activation resulted in significant increases in oxygenated hemoglobin concentration (oxy-Hb) in a broad region in and around the motor cortex. Overall, syncopated tapping was harder behaviorally and produced more cortical activation than synchronous tapping. Thus, we observed significant changes in oxy-Hb in direct relation to the complexity of the task. 

Cardiovascular and peripheral muscle efficiencies have been largely investigated as valid predictors of physical performance. In sports medicine, maximum oxygen consumption (VO2max) and lactate threshold (LT) are often used to quantify physical fitness in professional and recreational athletes alike. However, only few studies have attempted to establish if a association exists between brain activity and the successful exertion of physical exercise. In particular, it is unclear if factors such as motivation and resilience to fatigue (or lack thereof), which arguably originate within the brain, can be quantitatively related to physical performance. As a first step to improve our understanding of the role of the central nervous system in physical exercise, we investigated the association between cortical oxygenation measured with functional near infrared spectroscopy (fNIRS) and physical performance in healthy young adults during cycling.