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Highlights • Brief vigorous physical activity bouts benefited cognitive processing speed. • Bouted physical activity was specifically related to neurofunctional measures. • The number of associations increased with physical activity intensity. • Observed associations largely did not vary with accelerometer epoch length., Graphical abstract Image, graphical abstract, Background Structured vigorous physical activity (VPA) can improve cognitive control in children, but studies relating daily physical activity (PA) to cognitive control have yielded conflicting findings. While objectively measured daily PA summarizes all occurrences of PA within a registered period, a minimum duration of continuous PA is required for registration of a PA bout. Because brief bouts of high-intensity PA can account for a large proportion of children's daily activity-related energy expenditure, this study assessed whether daily and bouted VPA were selectively related to cognitive control in preadolescents relative to other PA intensities. Methods A total of 75 children between the ages of 8 and 10 years (49% girls) wore an ActiGraph wGT3X+ on the hip for 7 days. The acceleration signal from the vertical axis was summarized over 1 s, 5 s, and 15 s epochs. Daily and bouted moderate PA, moderate-to-vigorous PA, and VPA were measured. PA bouts were expressed as the frequency and time spent in 2 different continuous PA bouts, one lasting ≥10 s and the other lasting ≥30 s at a given intensity. Inhibitory control was assessed using behavioral responses to a modified flanker task (mean reaction time (RTmean) and accuracy). Attentional resource allocation and cognitive processing speed were measured using the amplitude and latency of the P3 component of event-related brain potentials, respectively. Associations between PA, behavioral indices of inhibitory control, P3 amplitude, and latency were assessed using hierarchical regression models. Results Daily VPA was not related to RTmean or accuracy on either congruent or incongruent trials. In contrast, more time spent in VPA bouts lasting ≥30 s predicted shorter P3 latency across epochs and flanker congruencies (all β ≤ –0.24, all p ≤ 0.04). The associations between shorter P3 latency and the time spent in moderate-to-vigorous PA bouts lasting ≥30 s were less consistent and largely limited to congruent trials (congruent: β (–0.31, –0.34)). No significant associations were observed upon correction for false discovery rate. Conclusion The pattern of uncorrected associations aligns with the dose–response literature and suggests that brief VPA bouts may yield the greatest benefits to cognitive processing speed in preadolescents. Future studies using measures of brain structure and function are needed to understand the mechanisms linking bouted VPA to neurocognitive function during childhood.

Background There is an increasing prevalence of physical inactivity during childhood, which is associated with a variety of health problems. However, the mechanisms by which acute exercise benefits cognition in childhood remains unknown. Here we describe the protocol for a randomized crossover trial called SNEACY (Sympathetic Nervous System & Exercise Affects Cognition in Youth), a study designed to better understand mechanisms linking acute exercise and cognition in 9–10-year-old healthy, cognitively normal children. Methods Children from the Greater Boston, MA region will be recruited to participate in this single center study. A randomized crossover design will be utilized, such that participants will act as their own controls, through initial randomization to condition assignment and condition counterbalancing across participants. One hundred three children will participate in three randomized acute interventions: moderate intensity treadmill exercise (20 min, 70–75% of their maximal heart rate), seated rest (20 min), and a Trier Social Stress Test for Children (14 min). These visits will occur on 3 three separate days, approximately 5–8 days apart. Before and after each intervention, children complete a variety of cognitive tasks measuring attentional inhibition while their neuroelectric activity is recorded. Variables of interest include EEG data, accuracy and reaction time, academic achievement, and salivary alpha amylase. Academic achievement is also assessed following interventions. In addition, children provide passive drool samples throughout the interventions to measure various biomarkers that may explain the acute exercise benefit on cognition. Discussion The results from this study could influence educational and public health recommendations to enhance cognition and learning in pre-adolescent children. Trial registration ClinicalTrials.gov NCT03592238. Registered on 19 July 2018

Shu-Shih Hsieh was supported by the Postdoctoral Research Abroad Program from the Ministry of Science and Technology in Taiwan (reference number: 109-2917-I-564-034). Francisco B. Ortega's research activity was supported by funds from Spanish Ministry of Economy and Competitiveness (Reference number: DEP2016-79512-R and DEP2017-91544-EXP) and the Andalusian Operational Programme supported with European Regional Development Funds (ERDF in English, FEDER in Spanish, project ref: B-CTS-355-UGR18)., Childhood obesity and its negative relation with children's brain health has become a growing health concern. Over the last decade, literature has indicated that physical activity attenuates cognitive impairment associated with obesity and excess adiposity in children. However, there is no comprehensive review that considers the extent to which these factors affect different domains of cognition. This narrative review comprehensively summarizes behavioral, neuroimaging, and neuroelectric findings associated with chronic physical activity and fitness on brain and cognition in childhood obesity. Based on the literature reviewed, increased adiposity has a demonstrated relationship with neurocognitive health via mechanisms triggered by central inflammation and insulin resistance, with the most pronounced decrements observed for cognitive domains that are prefrontal- and hippocampal-dependent. Fortunately, physical activity, especially interventions enhancing aerobic fitness and motor coordination, have demonstrated efficacy for attenuating the negative effects of obesity across different subdomains of structural and functional brain imaging, cognition, and multiple academic outcomes in children with overweight or obesity. Such mitigating effects may be accounted for by attenuated central inflammation, improved insulin sensitivity, and increased expression of neurotrophic factors. Lastly, individual differences appear to play a role in this relationship, as the manipulation of physical activity characteristics, the employment of a wide array of cognitive and academic measures, the inclusion of different adiposity measures that are sensitive to neurocognitive function, and the utilization of an inter-disciplinary approach have been found to influence the relationship between physical activity and excess adiposity on brain and cognition., Competitiveness DEP2016-79512-R DEP2017-91544-EXP, Andalusian Operational Programme, European Commission B-CTS-355-UGR18 B-CTS-355-UGR18

Background There is an increasing prevalence of physical inactivity during childhood, concurrent with a rise in obesity rates, which is associated with a variety of health problems. However, the extent to which increased body mass index (BMI) influences acute physical activity (PA) benefits on cognition in childhood remains unknown. The aim of this study was to examine whether BMI influences the effects of acute PA on inhibitory control task performance. Methods In a sample of 116 children pooled from four prior studies (ages 8-11; 51 females), demographic measures of age, sex, IQ, socioeconomic status, and aerobic fitness were considered along with BMI. Children participated in a counterbalanced, randomized crossover study, whereby they completed two different interventions; 20 minutes of treadmill walking (60-70% heart rate max) and restful reading (non-exercise control). Following each intervention, children performed a modified flanker task that manipulates inhibitory control demands. Correlations were conducted to determine the influence of demographic variables, fitness, and BMI on inhibitory control following each intervention. Subsequent hierarchical regression analyses were performed with significant demographic factors in the first step, aerobic fitness in the second step when significant, and BMI in the final step. Results Analyses indicated that children exhibited improved task performance (p's ≤ 0.001) and decreased interference (p = 0.04) following the walking intervention compared to the restful reading control condition, indicating greater benefits following acute PA across task condition, with selectively greater benefits for the task condition requiring greater inhibitory control. Regression analyses revealed that greater BMI was related to decreased performance following acute PA (p = 0.001); an association not observed following restful reading (p's ≥ 0.11). These results suggest that BMI negatively influences the effect of acute exercise on performance. Conclusion Confirming previous studies, these findings indicate beneficial effects of acute PA on a flanker task that modulates inhibitory control requirements, but the effects are significantly greater for task conditions requiring greater amounts of inhibitory control. Further, these beneficial effects of PA appear to be blunted in children with higher BMI. These findings suggest that the acute benefits of PA on cognition may not be fully realized in children with higher BMI.

Introduction: Brain network modularity is a principle that quantifies the degree to which functional brain networks are divided into subnetworks. Higher modularity reflects a greater number of within-module connections and fewer connections between modules, and a highly modular brain is often interpreted as a brain that contains highly specialized brain networks with less integration between networks. Recent work in younger and older adults has demonstrated that individual differences in brain network modularity at baseline can predict improvements in performance after cognitive and physical interventions. The use of brain network modularity as a predictor of training outcomes has not yet been examined in children. Method: In the present study, we examined the relationship between baseline brain network modularity and changes (post-intervention performance minus pre-intervention performance) in cognitive and academic performance in 8- to 9-year-old children who participated in an after-school physical activity intervention for 9 months (N = 78) as well as in children in a wait-list control group (N = 72). Results: In children involved in the after-school physical activity intervention, higher modularity of brain networks at baseline predicted greater improvements in cognitive performance for tasks of executive function, cognitive efficiency, and mathematics achievement. There were no associations between baseline brain network modularity and performance changes in the wait-list control group. Discussion: Our study has implications for biomarkers of cognitive plasticity in children. Understanding predictors of cognitive performance and academic progress during child development may facilitate the effectiveness of interventions aimed to improve cognitive and brain health.

Background Physical activity (PA) is beneficial for cognitive and brain health during preadolescence. Given that childhood obesity (OB) is a public health concern, investigating this effect in children with OB is an important societal consideration. Objectives To identify the effects of weight status and PA on neuroelectric indices of executive function in preadolescence. Methods Children were randomly assigned to a PA intervention or a wait-list control group and completed a task that manipulated inhibitory control, while task performance and neuroelectric (P3 component) outcomes were assessed. About 103 children with OB were matched to a sample of 103 normal weight (NW) children based on treatment allocation and demographic variables. Results Children with OB in the control group demonstrated reduced P3 amplitude from pre- to post-test, meanwhile those with OB in the PA intervention maintained P3 amplitude at post-test compared to pre-test. Additionally, NW children in the PA intervention group showed that decreased visceral adipose tissue corresponded with faster task performance, a relationship not observed in children with OB. Conclusions These results suggest that a 9-month PA intervention may be particularly beneficial to the cognitive and brain health of children with OB. These results are important to consider given the public health concerns associated with childhood OB.

Background Cesarean delivery (CS) is an increasingly common mode of delivery comprising over 30% of all deliveries in the U.S. The long-term impact of this delivery mode on child development remains unclear. Aims We investigated the relationship between mode of delivery (vaginal vs. CS) and timing of developmental milestones and adiposity in preadolescence, as well as additional milestones beyond motor/language development including toilet training, dressing, and feeding self. Study design This study utilized a retrospective survey given to a parent/guardian and dual energy x-ray absorptiometry in preadolescence, respectively. A composite z-score was calculated based on nine questions pertaining to developmental milestones i.e., parent-reported age for supporting head by self, rolling over, sitting up, standing, walking, talking, toilet-training, dressing, and feeding self. Subjects 7–10-year-old (N = 104) children in East-Central Illinois. Outcome measures Composite z-score for timing of attainment of developmental milestones, mode of delivery, and preadolescent adiposity. Results Vaginally-born children had a lower composite z-score, signifying earlier attainment of developmental milestones, relative to both emergency and planned CS-born children. Further, elective CS-born children had greater adiposity in preadolescence, relative to vaginal and emergency cesarean-section born children. Conclusions These findings suggest relationships between delivery mode, developmental milestones, and obesity in preadolescence. Additionally, they provide novel insights into the differential impact of elective versus emergency CS.

OBJECTIVE The objective of this study was to investigate the relationship between adiposity and cognition by using mean accuracy, mean reaction time, and intraindividual variability (IIV) among preadolescents. METHODS Children 7 to 9 years old (N = 233, 133 females) underwent dual-energy x-ray absorptiometry and a maximal oxygen consumption test to assess whole-body adiposity and aerobic fitness relative to fat-free mass (VO2 FF), respectively. Attentional inhibition was assessed by using a modified flanker task. IIV was assessed as standard deviation of reaction time and as a coefficient of variation of reaction time (CVRT). Hierarchical linear regression analyses were performed to examine the relationships between adiposity and cognitive measures following the adjustment of significant demographic factors, intelligence quotient, and VO2 FF. RESULTS Whole-body adiposity was negatively related to congruent trial mean accuracy and reaction time and to CVRT in both the congruent and incongruent trials. Differences in cognitive function across weight status were selectively evident for measures of IIV, such that children with overweight/obesity (≥ 85th BMI-for-age percentile) exhibited higher CVRT for both the congruent and incongruent trials. CONCLUSIONS This work provides additional evidence linking childhood obesity to poorer cognitive function and includes novel data extending the negative influence of adiposity to measures of intraindividual response variability in cognitive control, even after accounting for intellectual abilities, aerobic fitness, and demographic factors.

Magnetic Resonance Spectroscopy provides measures of brain chemistry that are sensitive to cardiorespiratory fitness and body composition. The concentration of N-acetyl aspartic acid (NAA) is of interest because it is a marker of neuronal integrity. The ratio of NAA to creatine, a standard reference metabolite, has been shown to correlate with measures of both cardiorespiratory fitness and body composition. However, previous studies have explored these effects in isolation, making it impossible to know which of these highly correlated measures drive the correlations with NAA/Cr. As a result, the mechanisms underlying their association remain to be established. We therefore conducted a comprehensive study to investigate the relative contributions of cardiorespiratory fitness and percent body fat in predicting NAA/Cr. We demonstrate that NAA/Cr in white matter is correlated with percent body fat, and that this relationship largely subsumes the correlation of NAA/Cr with cardiorespiratory fitness. These results underscore the association of body composition with axonal integrity and suggests that this relationship drives the association of NAA/Cr with physical fitness in young adults.

PURPOSE Obesity during adolescence has multisystem health consequences. The objective of this work was to determine whether preadolescent overweight/obese children's bones respond to a 9-month physical activity intervention by increasing bone density similar to healthy weight children. METHODS Participants included overweight/obese (BMI > 85%) and healthy weight (15% < BMI < 85%) preadolescents (8-9 yr old). Participants in the physical activity group participated in a 9-month physical activity curriculum every day after school. The wait list control group received no intervention. Both groups had overweight/obese children and healthy weight controls. Whole-body bone mineral content, area, and bone mineral apparent density (BMAD) were assessed using dual x-ray absorptiometry) at the beginning and end of the 9-month trial in the physical activity and control group. RESULTS Overweight/obese preadolescent children had higher BMAD than healthy weight children (P < 0.001 for spine, leg, and whole body). However, the density/weight (BMAD/lean mass) was lower in overweight/obese children than that in healthy weight children, indicating that the density of bones in overweight/obese children may not compensate sufficiently for the excessive load due to weight. The change in BMAD over 9 months was greater in healthy weight children than overweight/obese children in the whole body and leg, but not the lumbar spine. Physical activity caused a site-specific increase in bone density, affecting the legs more than the lumbar spine, but there was no significant difference in the effect of exercise between the healthy weight and the overweight/obese group. CONCLUSIONS The smaller change in BMAD over the 9 months and lower BMAD per unit lean mass in overweight/obese compared with healthy weight children may indicate a slower rate of bone mass accrual, which may have implications for bone health during skeletal growth in obese/overweight children.

Objectives: The aims of this study were (i) to examine the association between cardiorespiratory fitness and white matter volume and test whether those associations differ between normal-weight and overweight/obese children (ii) to analyze the association between other physical fitness components (i.e., motor and muscular) and white matter volume, and (iii) to examine whether the fitness-related associations in white matter volume were related to academic performance.Methods: Data came from two independent projects: ActiveBrains project (n = 100; 10.0 ± 1.1 years; 100% overweight/obese; Spain) and FITKids2 project (n = 242; 8.6 ± 0.5 years; 36% overweight/obese, United States). Cardiorespiratory fitness was assessed in both projects, and motor and muscular fitness were assessed in the ActiveBrains project. T1-weighted images were acquired with a 3.0 T S Magnetom Tim Trio system. Academic performance was assessed by standardized tests.Results: Cardiorespiratory fitness was associated with greater white matter volume in the ActiveBrain project (P < 0.001, k = 177; inferior fronto-opercular gyrus and inferior temporal gyrus) and in the FITKids project (P < 0.001, k = 117; inferior temporal gyrus, cingulate gyrus, middle occipital gyrus and fusiform gyrus) among overweight/obese children. However, no associations were found among normal-weight children in the FITKids project. In the ActiveBrains project, motor fitness was related to greater white matter volume (P < 0.001, k = 173) in six regions, specifically, insular cortex, caudate, bilateral superior temporal gyrus and bilateral supramarginal gyrus; muscular fitness was associated with greater white matter volumes (P < 0.001, k = 191) in two regions, particularly, the bilateral caudate and bilateral cerebellum IX. The white matter volume of six of these regions were related to academic performance, but after correcting for multiple comparisons, only the insular cortex remained significantly related to math calculations skills (β = 0.258; P < 0.005). In both projects, no brain regions showed a statistically significant negative association between any physical fitness component and white matter volume.Conclusion: Cardiorespiratory fitness may positively relate to white matter volume in overweight/obese children, and in turn, academic performance. In addition, motor and muscular fitness may also influence white matter volume coupled with better academic performance. From a public health perspective, implementing exercise interventions that combine aerobic, motor and muscular training to enhance physical fitness may benefit brain development and academic success.

Musical training has been associated with advantages in cognitive measures of IQ and verbal ability, as well as neural measures including white matter microstructural properties in the corpus callosum (CC) and the superior longitudinal fasciculus (SLF). We hypothesized that children who have musical training will have different microstructural properties in the SLF and CC. One hundred children aged 7.9 to 9.9 years (mean age 8.7) were surveyed for their musical activities, completed neuropsychological testing for general cognitive abilities, and underwent diffusion tensor imaging (DTI) as part of a larger study. Children who play a musical instrument for more than 0.5 hours per week (n = 34) had higher scores on verbal ability and intellectual ability (standardized scores from the Woodcock Johnson Tests of Cognitive Abilities), as well as higher axial diffusivity (AD) in the left SLF than those who did not play a musical instrument (n = 66). Furthermore, the intensity of musical practice, quantified as the number of hours of music practice per week, was correlated with axial diffusivity (AD) in the left SLF. Results are not explained by age, sex, socio-economic status, or physical fitness of the participants. Results suggest that the relationship between musical practice and intellectual ability is related to the maturation of white matter pathways in the auditory-motor system. The findings suggest that musical training may be a means of improving cognitive and brain health during development.

Objective Event-related brain potentials (ERPs) have been utilized to study the cognitive implications of health-related behaviors, although many questions remain regarding the neural correlates underlying the cognition and adiposity relationship in childhood. Specifically, it is unknown whether excess fat mass is associated with the neural correlates of motor preparation and activation. The present work examined interrelationships between adiposity and ERPs that index inhibition, stimulus evaluation, and motor planning. Method To further elucidate the neural components of inhibitory control that are sensitive to adiposity, N2, P3, and response- and stimulus-locked Lateralized Readiness Potential (LRPs) were measured while preadolescent children completed an attentional inhibition task. Whole body percent adiposity was measured via dual-energy x-ray absorptiometry (DXA). Results Adiposity was related to the response-locked LRP amplitudes and marginally to P3 amplitude during the incongruent trials, such that participants with less adiposity elicited larger LRP and P3 components. Furthermore, P3 was strongly related to participant reaction times, suggesting that while LRP is strongly associated with adiposity, P3 has a more direct relationship to behavioral task performance. Conclusions The results suggest that while different cognitive functions may be affected by health-related characteristics, stimulus evaluation and motor activation may be particularly sensitive to excess adiposity in children. These findings extend previous work implicating adiposity in cognitive health in the pediatric population. Study importance 1. What is already known about this subject? a. Excess adiposity is inversely associated with cognitive function in children. b. Adiposity has been associated with several event-related brain potentials, such that smaller P3 components, which index stimulus evaluation, and N2 components, which index attentional inhibition, are related to greater adiposity in children. c. The neural correlates underlying the cognition-adiposity relationship are under specified, and additional ERP components should be studied; one such component is the LRP, which underlies motor planning and activation. 2. What does your study add? a. Our results show that adiposity was related to the P3 and the response-locked LRP components such that children with less adiposity showed larger P3 and LRP waveforms. b. These findings suggest that two separable, though related, processes may be affected by adiposity in childhood: One involving the evaluation of a stimulus, represented by the P3, and one involving the activation of motor control, represented by the response-locked LRP. Clinical Registry Number: NCT02630667 at https://clinicaltrials.gov .

Children are becoming increasingly inactive, unfit, and overweight, yet there is relatively little causal evidence regarding the effects of physical activity on brain health during childhood. The present study examined the effects of an after-school physical activity program (FITKids2) on the microstructure of white matter tracts in 7- to 9-year-old children. We measured the microstructural properties of white matter via diffusion tensor imaging in one hundred and forty-three children before and after random assignment to either a 9-month after-school physical activity program (N=76, mean age = 8.7 years) or a wait list control group (N=67, mean age = 8.7 years). Our results demonstrate that children who participated in the physical activity program showed increased white matter microstructure in the genu of the corpus callosum, with no changes in white matter microstructure in the wait list control group which reflects typical development. Specifically, children in the physical activity program showed increases in fractional anisotropy (FA) and decreases in radial diffusivity (RD) in the genu from pre- to post-test, thereby suggesting more tightly bundled and structurally compact fibers (FA) and increased myelination (RD), with no changes in estimates of axonal fiber diameter (axial diffusivity, AD). The corpus callosum integrates cognitive, motor, and sensory information between the left and right hemispheres of the brain, and the white matter tract plays a role in cognition and behavior. Our findings reinforce the importance of physical activity for brain health during child development.

The importance of breakfast consumption for ideal cognitive performance has received much attention in recent years, although research on the topic has yielded mixed results. The present study utilized event-related brain potentials (ERPs) elicited during a modified flanker task to investigate the neuroelectric implications of receiving different mixed macronutrient beverages after an overnight fast. A repeated measures design was employed whereby preadolescent participants (9–10 years of age) completed cognitive testing while ERPs were collected during two non-consecutive testing sessions, one in which they received one of three treatment beverages consisting of mixed-macronutrient formulations (either Carbohydrate Blend, Sucrose, Maltodextrin) and the other in which they received a placebo drink containing Sucralose. Performance indices, ERPs, and blood glucose were recorded at three time points before the testing session and after the ingestion of each drink. While the behavioral performance indices and N2 results showed some evidence of glucose facilitation, the effects were small and selective. Participants who received the Maltodextrin treatment showed faster reaction times and more stable N2 amplitudes after ingesting the treatment beverage. The most robust effects were seen in the P3 amplitude measurement. Across the three drink groups, participants showed a marked amplitude increase over time after the placebo drink was ingested, although P3 amplitudes remained stable when a carbohydrate treatment drink was ingested. These effects were eliminated when changes in blood glucose were accounted for, suggesting that the neurolectric effects were directly related to glycemic change. These findings suggest that ingestion of carbohydrates after an overnight fast results in changes to the P3 amplitude of the ERP waveform elicited during an attentional inhibition task.

With the increasing prevalence of sedentary behaviors during childhood, a greater understanding of the extent to which excess adiposity and aerobic fitness relate to cognitive health is of increasing importance. To date, however, the vast majority of research in this area has focused on adiposity or fitness, rather than the possible inter-relationship, as it relates to cognition. Accordingly, this study examined the differential associations between body composition, aerobic fitness, and cognitive control in a sample of 204 (96 female) preadolescent children. Participants completed a modified flanker task (i.e., inhibition) and a switch task (i.e., cognitive flexibility) to assess two aspects of cognitive control. Findings from this study indicate that fitness and adiposity appear to be separable factors as they relate to cognitive control, given that the interaction of fitness and adiposity was observed to be nonsignificant for both the flanker and switch tasks. Fitness exhibited an independent association with both inhibition and cognitive flexibility whereas adiposity exhibited an independent association only with cognitive flexibility. These results suggest that while childhood obesity and fitness appear to both be related to cognitive control, they may be differentially associated with its component processes.

OBJECTIVE: To assess the effect of a physical activity (PA) intervention on brain and behavioral indices of executive control in preadolescent children. METHODS: Two hundred twenty-one children (7–9 years) were randomly assigned to a 9-month afterschool PA program or a wait-list control. In addition to changes in fitness (maximal oxygen consumption), electrical activity in the brain (P3-ERP) and behavioral measures (accuracy, reaction time) of executive control were collected by using tasks that modulated attentional inhibition and cognitive flexibility. RESULTS: Fitness improved more among intervention participants from pretest to posttest compared with the wait-list control (1.3 mL/kg per minute, 95% confidence interval [CI]: 0.3 to 2.4; d = 0.34 for group difference in pre-to-post change score). Intervention participants exhibited greater improvements from pretest to posttest in inhibition (3.2%, 95% CI: 0.0 to 6.5; d = 0.27) and cognitive flexibility (4.8%, 95% CI: 1.1 to 8.4; d = 0.35 for group difference in pre-to-post change score) compared with control. Only the intervention group increased attentional resources from pretest to posttest during tasks requiring increased inhibition (1.4 µV, 95% CI: 0.3 to 2.6; d = 0.34) and cognitive flexibility (1.5 µV, 95% CI: 0.6 to 2.5; d = 0.43). Finally, improvements in brain function on the inhibition task (r = 0.22) and performance on the flexibility task correlated with intervention attendance (r = 0.24). CONCLUSIONS: The intervention enhanced cognitive performance and brain function during tasks requiring greater executive control. These findings demonstrate a causal effect of a PA program on executive control, and provide support for PA for improving childhood cognition and brain health.

Event-related brain potentials (ERPs) have been instrumental for discerning the relationship between children's aerobic fitness and aspects of cognition, yet language processing remains unexplored. ERPs linked to the processing of semantic information (the N400) and the analysis of language structure (the P600) were recorded from higher and lower aerobically fit children as they read normal sentences and those containing semantic or syntactic violations. Results revealed that higher fit children exhibited greater N400 amplitude and shorter latency across all sentence types, and a larger P600 effect for syntactic violations. Such findings suggest that higher fitness may be associated with a richer network of words and their meanings, and a greater ability to detect and/or repair syntactic errors. The current findings extend previous ERP research explicating the cognitive benefits associated with greater aerobic fitness in children and may have important implications for learning and academic performance.

Objective To examine the effect of a single bout of moderate-intensity aerobic exercise on preadolescent children with attention-deficit/hyperactivity disorder (ADHD) using objective measures of attention, brain neurophysiology, and academic performance. Study design Using a within-participants design, task performance and event-related brain potentials were assessed while participants performed an attentional-control task following a bout of exercise or seated reading during 2 separate, counterbalanced sessions. Results Following a single 20-minute bout of exercise, both children with ADHD and healthy match control children exhibited greater response accuracy and stimulus-related processing, with the children with ADHD also exhibiting selective enhancements in regulatory processes, compared with after a similar duration of seated reading. In addition, greater performance in the areas of reading and arithmetic were observed following exercise in both groups. Conclusion These findings indicate that single bouts of moderately intense aerobic exercise may have positive implications for aspects of neurocognitive function and inhibitory control in children with ADHD.

This study used conditional accuracy functions (CAF), a method computing the mean accuracy of multiple reaction time (RT) ranges, to investigate the association between aerobic fitness and the utilization of cognitive control strategy during preadolescence. Thirty-eight higher- and lower-fit children were grouped according to their cardiorespiratory capacity (VO2max) and completed a modified flanker task. Seventeen young adults were recruited as a reference group of maturation. The results showed that higher-fit children exhibited an adult-like performance pattern, and demonstrated increased overall response accuracy compared to lower-fit children, with a disproportionally larger increase in individual responses when the time allowed for discriminative processing was constrained. These findings suggest that aerobic fitness is associated with enhanced cognitive control and development of a more proactive control strategy during flanker task in preadolescent children.

To examine the associations of macular pigment carotenoids (lutein, meso-zeaxanthin, and zeaxanthin), aerobic fitness, and central adiposity with hippocampal-dependent relational memory in prepubescent children.Children between 7 and 10 years of age (n = 40) completed a task designed to assess relational memory performance and participated in aerobic fitness, adiposity, and macular pigment optical density (MPOD) assessment. Aerobic fitness was assessed via a modified Balke treadmill protocol designed to measure maximal oxygen volume. Central adiposity was assessed via dual-energy x-ray absorptiometry. MPOD was measured psychophysically by the use of customized heterochromatic flicker photometry. Statistical analyses included correlations and hierarchical linear regression.Aerobic fitness and MPOD were associated negatively with relational memory errors (P .01), whereas central adiposity was associated positively with relational memory errors (P .05). Hierarchical regression analysis revealed that MPOD accounted for a significant amount of the variance in relational memory performance even after we accounted for aerobic fitness (β = -0.388, P = .007).Even after we adjusted for aerobic fitness and central adiposity, factors known to relate to hippocampal-dependent memory, MPOD positively and significantly predicted hippocampal-dependent memory performance.ClinicalTrials.gov: NCT01619826.

CONTEXT: Physical activity can improve cognitive and mental health, but the underlying mechanisms have not been established. OBJECTIVE: To present a conceptual model explaining the mechanisms for the effect of physical activity on cognitive and mental health in young people and to conduct a systematic review of the evidence. DATA SOURCES: Six electronic databases (PubMed, PsycINFO, SCOPUS, Ovid Medline, SportDiscus, and Embase) were used. STUDY SELECTION: School-, home-, or community-based physical activity intervention or laboratory-based exercise interventions were assessed. Studies were eligible if they reported statistical analyses of changes in the following: (1) cognition or mental health; and (2) neurobiological, psychosocial, and behavioral mechanisms. DATA EXTRACTION: Data relating to methods, assessment period, participant characteristics, intervention type, setting, and facilitator/delivery were extracted. RESULTS: Twenty-five articles reporting results from 22 studies were included. Mechanisms studied were neurobiological (6 studies), psychosocial (18 studies), and behavioral (2 studies). Significant changes in at least 1 potential neurobiological mechanism were reported in 5 studies, and significant effects for at least 1 cognitive outcome were also found in 5 studies. One of 2 studies reported a significant effect for self-regulation, but neither study reported a significant impact on mental health. LIMITATIONS: Small number of studies and high levels of study heterogeneity. CONCLUSIONS: The strongest evidence was found for improvements in physical self-perceptions, which accompanied enhanced self-esteem in the majority of studies measuring these outcomes. Few studies examined neurobiological and behavioral mechanisms, and we were unable to draw conclusions regarding their role in enhancing cognitive and mental health.

Standardized tests have been used to forecast scholastic success of school-age children, and have been related to intelligence, working memory, and inhibition using neuropsychological tests. However, ERP correlates of standardized achievement have not been reported. Thus, the relationship between academic achievement and the P3 component was assessed in a sample of 105 children during performance on a Go/NoGo task. The Wide Range Achievement Test – 3rd edition was administered to assess aptitude in reading, spelling, and arithmetic. Regression analyses indicated an independent contribution of P3 amplitude to reading and arithmetic achievement beyond the variance accounted for by IQ and school grade. No such relationship was observed for spelling. These data suggest that the P3, which reflects attentional processes involved in stimulus evaluation and inhibitory control may be a biomarker for academic achievement during childhood.

The influence of cardiorespiratory fitness on the modulation of cognitive control was assessed in preadolescent children separated into higher- and lower-fit groups. Participants completed compatible and incompatible stimulus–response conditions of a modified flanker task, consisting of congruent and incongruent arrays, while ERPs and task performance were concurrently measured. Findings revealed decreased response accuracy for lower- relative to higher-fit participants with a selectively larger deficit in response to the incompatible stimulus–response condition, requiring the greatest amount of cognitive control. In contrast, higher-fit participants maintained response accuracy across stimulus–response compatibility conditions. Neuroelectric measures indicated that higher-fit, relative to lower-fit, participants exhibited global increases in P3 amplitude and shorter P3 latency, as well as greater modulation of P3 amplitude between the compatible and incompatible stimulus–response conditions. Similarly, higher-fit participants exhibited smaller error-related negativity (ERN) amplitudes in the compatible condition, and greater modulation of the ERN between the compatible and incompatible conditions, relative to lower-fit participants who exhibited large ERN amplitudes across both conditions. These findings suggest that lower-fit children may have more difficulty than higher-fit children in the flexible modulation of cognitive control processes to meet task demands.

Objective: To investigate the relationship between aerobic fitness and cognitive variability in preadolescent children. Method: Forty-eight preadolescent children (25 males, 23 females, mean age 10.1 years) were grouped into higher- and lower-fit groups according to their performance on a test of aerobic capacity (VO2max). Cognitive function was measured via behavioral responses to a modified flanker task. The distribution in reaction time was calculated within each participant to assess intraindividual variability of performance. Specifically, the standard deviation and coefficient variation of reaction time were used to represent cognitive variability. Results: Preadolescent children, regardless of fitness, exhibited longer reaction time, increased response variability, and decreased response accuracy to incongruent compared to congruent trials. Further, higher-fit children were less variable in their response time and more accurate in their responses across conditions of the flanker task, while no group differences were observed for response speed. Conclusion: These findings suggest that fitness is associated with better cognitive performance during a task that varies cognitive control demands, and extends this area of research to suggest that intraindividual variability may be a useful measure to examine the relationship between fitness and cognition during preadolescence.

The effect of an acute bout of moderate treadmill walking on behavioral and neuroelectric indexes of the cog- nitive control of attention and applied aspects of cognition involved in school-based academic performance were as- sessed. A within-subjects design included 20 preadolescent participants (age9.50.5 years; eight female) to assess ex- ercise-induced changes in performance during a modified flanker task and the Wide Range Achievement Test 3. The resting session consisted of cognitive testing followed by a cardiorespiratory fitness assessment to determine aerobic fitness. The exercise session consisted of 20 min of walking on a motor-driven treadmill at 60% of estimated maximum heart rate followed by cognitive testing once heart rate re- turned to within 10% of pre-exercise levels. Results indicated an improvement in response accuracy, larger P3 amplitude, and better performance on the academic achievement test following aerobic exercise relative to the resting session. Collectively, these findings indicate that single, acute bouts of moderately-intense aerobic exercise (i.e. walking) may im- prove the cognitive control of attention in preadolescent chil- dren, and further support the use of moderate acute exercise as a contributing factor for increasing attention and aca- demic performance. These data suggest that single bouts of exercise affect specific underlying processes that support cognitive health and may be necessary for effective function- ing across the lifespan. © 2009 IBRO. Published by Elsevier Ltd. All rights reserved.

This study examined the effects of cardiorespiratory fitness, heart rate recovery, and physical activity on working memory in breast cancer survivors and age-matched controls.Using a case-control design, 32 women who had received a breast cancer diagnosis and completed primary treatment within the past 36-months (11 radiation only; 21 chemotherapy) and 30 age-matched women with no previous cancer diagnosis completed a n-back continuous performance task commonly used as an assessment of working memory. In addition, cardiorespiratory fitness and heart rate recovery were measured during a submaximal graded exercise test and physical activity was measured using 7-days of accelerometer monitoring.Breast cancer survivors who had received chemotherapy had poorer heart rate recovery (p = .010) and engaged in less physical activity than women who had received radiation only (p = .004) or non-cancer controls (p = .029). Cancer treatment (radiation; chemotherapy) predicted differences in reaction times on the 1-back working memory task (p = .029). However, more rapid heart rate recovery predicted shorter reaction times on the 1-back task in the age-matched control group (p = .002). All participants with greater cardiorespiratory fitness displayed greater accuracy independent of disease status on the 1-back task (p = .017). No significant group differences in reaction times were observed for 2-back target trials between breast cancer survivors and controls. However, greater total physical activity predicted shorter reaction times in breast cancer survivors (radiation, chemotherapy) on the 2-back task (p = .014). In addition, all participants who exhibited more rapid heart rate recovery demonstrated better greater accuracy regardless of disease status (p = .013).These findings support differences in physical activty participation, heart rate recovery, and 1- and 2-back working memory reaction times between breast cancer survivors and age-matched controls. Greater cardiorespiratory fitness, heart rate recovery, and physical activity were positively associated with better working memory performance across conditions.

Growing evidence suggests that aerobic fitness benefits the brain and cognition during childhood. The present study is the first to explore cortical brain structure of higher fit and lower fit 9- and 10-year-old children, and how aerobic fitness and cortical thickness relate to academic achievement. We demonstrate that higher fit children (>70th percentile VO2max) showed decreased gray matter thickness in superior frontal cortex, superior temporal areas, and lateral occipital cortex, coupled with better mathematics achievement, compared to lower fit children (

Background: Cognitive control (also known as executive function) encompasses mental processes that underlie goal-directed behavior, and it enables us to adjust our behavior according to changing environmental demands. Previous research among children has demonstrated that aerobic fitness and obesity have contrasting and selective effects on cognitive control. However, the relationship between water intake and childhood cognitive control remains inadequately studied. This study investigated the relationship between total water intake and cognitive control among prepubertal children (8-9-year olds). Methods: Children between 8 and 9 years of age (n = 63) performed a modified flanker task to assess cognitive control related to inhibition (ability to resist distractions and maintain focus). Diet was measured using 3-day food records. Total water was defined as water consumed from drinking water, beverages, and food. Results: A comparison of task performance across the median intake of total water revealed that children above the median exhibited shorter reaction times across multiple conditions of the flanker task, requiring variable amounts of cognitive control. Further, after adjustment of age, IQ, socioeconomic status, weight status, and aerobic fitness level, the proportion of intake comprised of water (%TW) was negatively correlated with reaction time interference, that is, the ability to maintain task performance when task conditions demanded greater inhibition. Conclusions: These results indicate an association between water intake and cognitive control using a task that modulates inhibition. Specifically, higher water intake correlated with greater ability to maintain task performance when inhibitory demands are increased. Future work is needed to determine the mechanism by which water influences cognitive control among children.

Objectives To evaluate the effects of a 9-month physical activity intervention on changes in adiposity and cognitive control based on pretrial weight status (ie, healthy weight vs obese) in children. Study design Participants included obese (n = 77) and matched healthy-weight (n = 77) preadolescents (8-9 years) who participated in a 9-month physical activity randomized controlled trial. Cognitive function was assessed with an inhibitory control task (modified flanker task). Results After the 9-month physical activity intervention, participants exhibited a reduction in adiposity. In contrast, children in the waitlist-control condition, particularly children identified as obese pretrial, gained visceral adipose tissue (P = .008). Changes in visceral adipose tissue were related to changes in cognitive performance, such that the degree of reduction in visceral adipose tissue directly related to greater gains in inhibitory control, particularly among obese intervention participants (CI −0.14, −0.04; P = .001). Conclusions Participation in a daily physical activity program not only reduces adiposity but also improves children's cognitive function as demonstrated by an inhibitory control task. Furthermore, these findings reveal that the benefits of physical activity to improvements in cognitive function are particularly evident among children who are obese. Trial registration ClinicalTrials.gov : NCT01334359 and NCT01619826 .

Background: Converging evidence now indicates that aerobic fitness and adiposity are key correlates of childhood cognitive function and brain health. However, the evidence relating dietary intake to executive function/cognitive control remains limited. Objective: The current study assessed cross-sectional associations between performance on an attentional inhibition task and dietary fatty acids (FAs), fiber, and overall diet quality among children aged 7–9 y (n = 65). Methods: Attentional inhibition was assessed by using a modified flanker task. Three-day food records were used to conduct nutrient-level analyses and to calculate diet quality (Healthy Eating Index–2005) scores. Results: Bivariate correlations revealed that socioeconomic status and sex were not related to task performance or diet measures. However, age, intelligence quotient (IQ), pubertal staging, maximal oxygen uptake (VO2max), and percentage of fat mass (%fat mass) correlated with task accuracy. Hierarchical regression models were used to determine the relation between diet variables and task accuracy and reaction time across both congruent and incongruent trials of the flanker task. After adjustment of confounding variables (age, IQ, pubertal staging, VO2max, and %fat mass), congruent accuracy was positively associated with insoluble fiber (β = 0.26, P = 0.03) and total dietary fiber (β = 0.23, P = 0.05). Incongruent response accuracy was positively associated with insoluble fiber (β = 0.35, P < 0.01), pectins (β = 0.25, P = 0.04), and total dietary fiber (β = 0.32, P < 0.01). Higher diet quality was related to lower accuracy interference (β = −0.26, P = 0.03), whereas higher total FA intake was related to greater accuracy interference (β = 0.24, P = 0.04). No statistically significant associations were observed between diet variables and reaction time measures. Conclusion: These results demonstrate that children’s diet quality, specifically dietary fiber, is an important correlate of performance on a cognitive task requiring variable amounts of cognitive control.

Nutrition plays an important role in brain structure and function, and the effects of diet may even be greater in those at greater risk of cognitive decline, such as individuals with cancer-related cognitive impairment. However, the relation of dietary components to cognitive function in cancer survivors is unknown. The objective of this study was to determine whether breast cancer survivors (BCS) evidenced impairments in interference control, a component of cognitive control, compared to age-matched women with no prior history of cancer, and to examine the moderating role of diet on cognitive function.In this cross-sectional study, a modified flanker task was used to assess interference control in BCS (n = 31) and age-matched women with no prior history of cancer (n = 30). Diet was assessed with 3-day food records. Differences between BCS and age-matched controls were assessed using linear mixed models, and multilevel regression analyses were conducted to assess the moderating role of diet on cognitive performance.Cognitive performance was not different between groups. Fruit intake and vegetable intake were significantly associated with better performance on the incompatible condition of the flanker task (i.e., shorter reaction time and increased accuracy), independent of disease status. The association between dietary components and cognition was stronger for the incompatible incongruent condition, suggesting that fruit and vegetables may be important for the up-regulation of cognitive control when faced with higher cognitive demands.There was no difference in performance on an interference control task between BCS and age-matched controls. The data suggest that greater fruit intake and vegetable intake were positively associated with interference control in both BCS and age-matched controls.

The present investigation examined the sexual dimorphic patterns of cardiorespiratory fitness to working memory in preadolescent children (age range: 7.7-10.9). Data were collected in three separate studies (Study 1: n = 97, 42 females; Study 2: n = 95, 45 females; Study 3: n = 84, 37 females). All participants completed a cardiorespiratory fitness assessment in addition to a specific measure of working memory (i.e. the operation span task, the n-back task, or the Sternberg task). Results from all three samples revealed that higher cardiorespiratory fitness levels were associated with better working memory performance only for males with no such relation observed for females. In addition, the sexually dimorphic pattern was selective for the most challenging working memory conditions in each task. Together, these findings reveal new evidence that cardiorespiratory fitness is selectively related to better working memory performance for male children. This investigation provides additional insight into how interventions aimed at improving fitness may influence cognitive development differentially among preadolescent children.

Aerobic fitness has been found to play a positive role in brain and cognitive health of children. Yet, many of the neural biomarkers related to aerobic fitness remain unknown. Here, using diffusion tensor imaging (DTI), we demonstrated that higher aerobic fitness was related to greater estimates of white matter microstructure in children. Higher fit 9- and 10-year-old children showed greater fractional anisotropy (FA) in sections of the corpus callosum, corona radiata, and superior longitudinal fasciculus, compared to lower fit children. The FA effects were primarily characterized by aerobic fitness differences in radial diffusivity (RD), thereby raising the possibility that estimates of myelination may vary as a function of individual differences in fitness during childhood. White matter structure may be another potential neural mechanism of aerobic fitness that assists in efficient communication between gray matter regions as well as the integration of regions into networks.

OBJECTIVE: To investigate the effect of a 9-month physical activity intervention on cardiorespiratory fitness and adiposity among prepubertal children. METHODS: Prepubertal children (8- to 9-year-olds, N = 220, 103 girls) were randomly assigned to a 9-month physical activity intervention or a control group. The intervention provided 70 minutes (5 days/week) of moderate to vigorous physical activity. Maximum oxygen consumption (Vo2max percentile) and dual-energy radiograph absorptiometry measured cardiorespiratory fitness and adiposity, respectively. Intention-to-treat analysis was performed to assess baseline and follow-up cardiorespiratory fitness, percentage fat mass (%FM), percentage central fat mass (%CFM), and estimated visceral adipose tissue (VAT) area. RESULTS: The intervention group increased in cardiorespiratory fitness (5.4th percentile; 95% confidence interval [CI], 1.8 to 8.9) and decreased in %FM (−0.7%; 95% CI, −1.1 to −0.4) and %CFM (−1.3%; 95% CI, −1.9 to −0.7). Reductions in %FM were evident for both nonoverweight (−0.62%; 95% CI, −1.07 to −0.17) and overweight or obese (−0.86%; 95% CI,−1.46 to −0.25) intervention participants. Conversely, the control group displayed no change in cardiorespiratory fitness while exhibiting increases in %FM (0.4%; 95% CI, 0.1 to 0.7), %CFM (0.6; 95% CI, 0.1 to 1.1), and VAT area (3.0 cm2; 95% CI, 1.6 to 4.4). Nonoverweight control participants increased in %FM (0.52%; 95% CI, 0.13 to 0.91), and their overweight and obese counterparts increased in VAT (4.76 cm2; 95% CI, 1.90 to 7.63). CONCLUSIONS: The physical activity intervention improved cardiorespiratory fitness, reduced %FM, and prevented accumulation of %CFM among prepubertal children with varying adiposity levels. These findings provide support for daily physical activity recommendations to prevent excess fat mass accumulation in childhood.

Obesity is associated with cognitive decline in later adulthood; however, the implication of obesity on childhood cognitive and brain health remains controversial. Accordingly, this study investigated the effect of weight status (healthy weight [HW] or obese [OB]) on behavioral and neuroelectric measures of cognitive control among 80 prepubertal children (8-9-years). HW (n=40) and OB (n=40) children completed a switch (cognitive flexibility) task while event-related brain potentials were concurrently measured. Adiposity and aerobic fitness were assessed using DXA and VO2max, respectively. Groups were matched on key covariates including age, sex, IQ, SES, fat-free VO2max, and ADHD. There were no differences in response accuracy or reaction time between groups on both the homogenous and heterogeneous trials. However, obese children exhibited greater global switch costs related to response accuracy. In addition, obese children displayed smaller central-parietal P3 amplitude during heterogeneous trials, signi...

IntroductionThere is a growing trend of inactivity among children, which may not only result in poorer physical health, but also poorer cognitive health. Previous research has shown that lower fitness has been related to decreased cognitive function for tasks requiring perception, memory, and cognitive control as well as lower academic achievement.PurposeTo investigate the relationship between aerobic fitness, learning, and memory on a task that involved remembering names and locations on a fictitious map. Different learning strategies and recall procedures were employed to better understand fitness effects on learning novel material.MethodsForty-eight 9-10 year old children (n = 24 high fit; HF and n = 24 low fit; LF) performed a task requiring them to learn the names of specific regions on a map, under two learning conditions in which they only studied (SO) versus a condition in which they were tested during study (TS). The retention day occurred one day after initial learning and involved two different recall conditions: free recall and cued recall.ResultsThere were no differences in performance at initial learning between higher fit and lower fit participants. However, during the retention session higher fit children outperformed lower fit children, particularly when the initial learning strategy involved relatively poor recall performance (i.e., study only versus test-study strategy).ConclusionsWe interpret these novel data to suggest that fitness can boost learning and memory of children and that these fitness-associated performance benefits are largest in conditions in which initial learning is the most challenging. Such data have important implications for both educational practice and policy.

This study examined behavioral and neuroelectric intra-individual variability (IIV) in preadolescent children during a task requiring variable amounts of cognitive control. The current study further examined whether IIV was moderated by aerobic fitness level. Participants performed a modified flanker task, comprised of congruent and incongruent arrays, within compatible and incompatible stimulus–response conditions. Results revealed that congruent, relative to incongruent, conditions were associated with less IIV of RT. Further, less IIV of RT, P3 amplitude, and P3 latency was observed for the compatible relative to the incompatible condition. Higher fitness was associated with shorter and less variable RT only for the incompatible condition, with no fitness-related differences observed for P3 variability. The findings suggest that conditions requiring greater cognitive control are associated with increased IIV, and that higher fitness may be associated with greater integrity of cognitive control systems during development.

This study examined whether individual differences in aerobic fitness are associated with differences in activation of cognitive control brain networks in preadolescent children. As expected, children performed worse on a measure of cognitive control compared with a group of young adults. However, individual differences in aerobic fitness were associated with cognitive control performance among children. Lower-fit children had disproportionate performance cost in accuracy with increasing task difficulty, relative to higher-fit children. Brain activation was compared between performance-matched groups of lower- and higher-fit children. Fitness groups differed in brain activity for regions associated with response execution and inhibition, task set maintenance, and top-down regulation. Overall, differing activation patterns coupled with different patterns of brain-behavior correlations suggest an important role of aerobic fitness in modulating task strategy and the efficiency of neural networks that implement cognitive control in preadolescent children.

The present investigation is the first to explore the association between childhood aerobic fitness and basal ganglia structure and function. Rodent research has revealed that exercise influences the striatum by increasing dopamine signaling and angiogenesis. In children, higher aerobic fitness levels are associated with greater hippocampal volumes, superior performance on tasks of attentional and interference control, and elevated event-related brain potential indices of executive function. The present study used magnetic resonance imaging to investigate if higher-fit and lower-fit 9- and 10-year-old children exhibited differential volumes of other subcortical brain regions, specifically the basal ganglia involved in attentional control. The relationship between aerobic fitness, dorsal and ventral striatum volumes and performance on an attention and inhibition Eriksen flanker task was also examined. The results indicated that higher-fit children showed superior flanker task performance compared to lower-fit children. Higher-fit children also showed greater volumes of the dorsal striatum, and dorsal striatum volume was negatively associated with behavioral interference. The results support the claim that the dorsal striatum is involved in cognitive control and response resolution and that these cognitive processes vary as a function of aerobic fitness. No relationship was found between aerobic fitness, the volume of the ventral striatum and flanker performance. The findings suggest that increased childhood aerobic fitness is associated with greater dorsal striatal volumes and that this is related to enhanced cognitive control. Because children are becoming increasingly overweight, unhealthy and unfit, understanding the neurocognitive benefits of an active lifestyle during childhood has important public health and educational implications.

Because children are becoming overweight, unhealthy, and unfit, understanding the neurocognitive benefits of an active lifestyle in childhood has important public health and educational implications. Animal research has indicated that aerobic exercise is related to increased cell proliferation and survival in the hippocampus as well as enhanced hippocampal-dependent learning and memory. Recent evidence extends this relationship to elderly humans by suggesting that high aerobic fitness levels in older adults are associated with increased hippocampal volume and superior memory performance. The present study aimed to further extend the link between fitness, hippocampal volume, and memory to a sample of preadolescent children. To this end, magnetic resonance imaging was employed to investigate whether higher- and lower-fit 9- and 10-year-old children showed differences in hippocampal volume and if the differences were related to performance on an item and relational memory task. Relational but not item memory is primarily supported by the hippocampus. Consistent with predictions, higher-fit children showed greater bilateral hippocampal volumes and superior relational memory task performance compared to lower-fit children. Hippocampal volume was also positively associated with performance on the relational but not the item memory task. Furthermore, bilateral hippocampal volume was found to mediate the relationship between fitness level (VO(2) max) and relational memory. No relationship between aerobic fitness, nucleus accumbens volume, and memory was reported, which strengthens the hypothesized specific effect of fitness on the hippocampus. The findings are the first to indicate that aerobic fitness may relate to the structure and function of the preadolescent human brain.