REACTION TIME PROCESSING COMPONENT IS RELATED TO AVAILABLE CEREBRAL OXYGEN

Ando, S., Yamada, Y., & Kokubu, M. (2009). Reaction time to peripheral visual stimuli during exercise under hypoxia. A paper presented at the 14th Annual Congress of the European College of Sport Science, Oslo, Norway, June 24-27.

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"Reaction time to peripheral visual stimuli increases during exercise at high workloads. However, physiological mechanisms underlying the detrimental effects of exercise on reaction time to peripheral visual stimuli remain to be elucidated. The purpose of this study was to test if hypoxia affected reaction time to peripheral visual stimuli during exercise. We expected that if a decrease in oxygen availability is responsible for the increase in reaction time to peripheral visual stimuli during exercise, reaction time to peripheral visual stimuli would, to a greater extent, increase during exercise under hypoxia when compared to exercise under normoxia."

Male Ss (N = 10) performed reaction time tasks at rest and during and after cycling at three different workloads of 40%, 60%, and 80% peak oxygen uptake (VO2peak) under either normoxia (oxygen level 21%) or hypoxia (oxygen level 16%). Visual stimuli were randomly presented at 10 to either the right or left of the midpoint of the Ss eyes. Cerebral oxygenation was continuously monitored over the right frontal cortex using near-infrared spectroscopy. Reaction time was divided into premotor and motor time components based on the elements of a electromyogramic recording of the right forearm. Premotor time was used to indicate the efficiency of central information processing.

Under normoxia, premotor time was significantly longer during exercise at 80% VO2peak relative to that of rest. Under hypoxia, premotor time was significantly longer during exercise at all workloads relative to rest. Increase in premotor time during exercise was negatively correlated with corresponding cerebral oxygenation when data from normoxia and hypoxia were combined together.

Implication. The increase in premotor time to peripheral visual stimuli during exercise is closely associated with a decrease in cerebral oxygenation. The level of cerebral oxygenation influences visual perceptual performance during exercise.

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