Childhood fitness and brain development: A narrative review of behavioral and neuroimaging studies / 体力科学

The global pandemic of childhood physical inactivity and the associated reduction in physical fitness have become the major health problem. Based on such background, there is growing interest in child development research to investigate the associations among physical fitness, cognitive function, and the underlying neurobiological mechanisms. In the present narrative review, we first summarize the findings from behavioral studies that examined the relations of childhood fitness to academic performance and executive function. Because these behavioral findings remain controversial due to methodological inconsistencies, we further discuss differences in independent variables (e.g., physical activity vs. fitness), confounders (e.g., socioeconomic status), study designs (e.g., cross-sectional vs. randomized controlled trial), and assessments used to measure academic performance and executive function (e.g., task difficulty). Subsequently, we introduce neuroimaging studies on brain volume, task-evoked brain activation, and white matter fiber integrity which may provide mechanistic insights into the behavioral observations. To date, several randomized controlled trials using advanced imaging techniques showed that regular physical activity may change brain activations during executive function tasks and improve white matter fiber integrity in children. Collectively, our literature review suggests that regular physical activity leading to increase in physical fitness is likely to contribute to healthy brain development. Nevertheless, the current evidence is still limited and inconclusive, thus further rigorously designed randomized controlled trails are needed to clarify the association between childhood fitness and brain development.

EFFECTS OFEXERCISE INTENSITY AND PHYSICAL ACTIVITY LEVELS ON THE BRAIN AND COGNITION / 体力科学

The interactive effects of exercise intensity and physical activity level on the brain and cognition of young adults were investigated using the electromyographic reaction time (EMG-RT), the P3, and the NoGo P3, as well as the contingent negative variation (CNV) of event-related brain potentials. Participants (n＝26 : 24.0 ± 0.7 years) were divided on the basis of their regular physical activity level into active and inactive groups. Then, they performed a Go/NoGo reaction time task in the no exercise, control condition ; as well as after light, moderate, and hard cycling exercises. Results indicated that increases in P3 and NoGo P3 amplitude following moderate exercise were larger in the inactive group, suggesting that inactive individuals were more sensitive to exercise intensity than active individuals. Active individuals might be better able to sustain their attention during the Go/NoGo reaction time task, despite the exercise intensity. These findings are suggestive of a differential effect of exercise intensity on cognitive function that might be dependent on the level of regular physical activity. The effects of exercise intensity on EMG-RTs were observed across groups. However, the P3 latency was not affected by exercise intensity. These contradictory results are possible related to the nature of the cognitive task, such as its difficulty. Moreover, increases in CNV amplitudes following moderate exercise were larger than in other exercise conditions across groups, suggesting that motor preparation process is also facilitated by moderate, acute exercise. These findings provide additional evidence for the beneficial effects of acute aerobic exercise on the brain and cognition of young adults.

CHANGES IN SOMATOSENSORY INPUT FOLLOWING LOCAL MUSCLE FATIGUE / 体力科学

We studied whether exercise fatigue affects somatosensorv input using somatosensory evoked potential (SEP) . Sixteen subjects performed intermittent grip strength exercises with muscle fatigue while ignoring electrical stimulation given to an elbow. We induced SEP in the exercise task (during contraction) in every stage (first stage, middle stage and final stage) . In addition, we induced SEP in the exercise task during relaxation in the first stage and final stage. As a result, the early component amplitude of SEP decreased with the progress of exercise (manifestation of muscle fatigue) during contraction and relaxation. Our findings suggested that somatosensory input decreased with the manifestation of muscle fatigue. Somatosensory input is necessary for control of voluntary movement. Therefore, we speculate that these factors play a role in decreased performance of athletes competing in long-duration events.