Effects of acute aerobic exercise on a task‐switching protocol and brain‐derived neurotrophic factor concentrations in young adults with different levels of cardiorespiratory fitness

What is the central question of this study? Neurocognitive functions can be enhanced by acute aerobic exercise, which could be associated with changes in serum brain-derived neurotrophic factor (BDNF) concentrations. We aimed to explore acute exercise-induced changes in BDNF concentrations, neuropsychological and neurophysiological performances when individuals with different levels of cardiorespiratory fitness performed a cognitive task. What is the main finding and its importance? Only young adults with higher cardiorespiratory fitness could attain switching cost and neurophysiological benefits via acute aerobic exercise. The mechanisms might be fitness dependent. Although acute aerobic exercise could enhance serum BDNF concentrations, changes in peripheral BDNF concentrations could not be the potential factor involved in the beneficial effects on neurocognitive performance. This study investigated the effects of acute aerobic exercise on neuropsychological and neurophysiological performances in young adults with different cardiorespiratory fitness levels when performing a task-switching protocol and explored the potential associations between acute aerobic exercise-induced changes in serum brain-derived neurotrophic factor (BDNF) concentrations and various neurocognitive outcomes. Sixty young adults were categorized into one control group (i.e. non-exercise-intervention; n = 20) and two exercise-intervention (EI) groups [i.e. higher (EIH , n = 20) and lower (EIL , n = 20) cardiorespiratory fitness] according to their maximal oxygen consumption. At baseline and after either an acute bout of 30 min of moderate-intensity aerobic exercise or a control period, the neuropsychological and neurophysiological performances and serum BDNF concentrations were measured when the participants performed a task-switching protocol involving executive control and greater demands on working memory. The results revealed that although acute aerobic exercise decreased reaction times across three (i.e. pure, switching and non-switching) conditions in both EI groups, only the EIH group showed a smaller switching cost and larger P3 amplitudes after acute exercise, supporting the view that the mechanisms of neural functioning that underlie the effects of such exercise may be fitness dependent. In addition, serum BDNF concentrations were elevated after acute exercise for both EI groups, but there were no significant correlations between the changes in BDNF concentrations and changes in neuropsychological and neurophysiological performances for either group, suggesting that serum BDNF could not be the potential factor involved in the beneficial effects on neuropsychological and neurophysiological performances seen in young adults after acute aerobic exercise.