Lower-fit Children Research Articles

Activity patterns of primary school children during participation in The Daily Mile

The Daily Mile is a popular physical activity initiative in primary schools, yet little is known regarding the activity patterns of children during The Daily Mile. Eighty children (10.4 ± 0.7 years) participated in The Daily Mile (20-min). Activity patterns were assessed using global positioning systems (total distance and age-specific speed zones), alongside heart rate. Cardiorespiratory fitness was assessed using the Multi-Stage Fitness Test. Participants covered a distance of 2511 ± 550 m during The Daily Mile, and heart rate was 163 ± 27 beats.min−1. Participants travelled the furthest distance, and were most intermittent, during the first 5 min (main effect of time, both p < 0.001). Boys ran further and their activity was more intermittent compared to girls (main effect of sex, both p < 0.001). Moreover, the highest fit children ran further than less fit children (main effect of fitness, p < 0.001). This study provides novel evidence of the nature of physical activity during The Daily Mile; demonstrating that children covered, on average, 1.5-miles and exercised at a moderate-to-vigorous intensity. Furthermore, boys covered a greater distance and were more intermittent than girls; whilst higher fit children ran further than lower fit children. In summary, The Daily Mile makes a valuable contribution to in-school physical activity targets in all children.

The association between aerobic fitness and congruency sequence effects in preadolescent children

Aerobic fitness has previously been related to cognitive control in preadolescents; however, these investigations have generally relied on global measures of performance. Thus, we have little understanding of how aerobic fitness may relate to trial-by-trial modulations in cognitive control. This study utilized congruency sequence effects (CSEs), which characterize how behavior on the current trial is influenced by the previous trial, to investigate the relation of aerobic fitness on varying levels of cognitive control. One hundred eighty-seven children completed tests of aerobic fitness and a flanker task. Regressions were performed to determine relationships between CSE sequences and aerobic fitness while controlling for other potential confounding factors (e.g., age, sex, IQ). Lower-fit children were less able to modulate cognitive control during sequences requiring relatively less cognitive control. Additionally, lower-fit children were less able to adjust for variable levels of cognitive control during relatively more difficult sequences. Lastly, lower-fit children had longer reaction times (RTs) for all sequences in the condition requiring greater amounts of cognitive control. These findings corroborate the importance of aerobic fitness for cognitive control in school-aged children, and extend the literature by demonstrating a relationship between fitness and trial-by-trial modulations in control demands.

Fitness and ERP Indices of Cognitive Control Mode during Task Preparation in Preadolescent Children.

A growing number of studies conducted over the past decade have demonstrated that greater aerobic fitness is associated with superior cognitive control in preadolescent children. Several studies have suggested that the relationship between fitness and cognitive control may be attributed to differential reliance on proactive vs. reactive cognitive control modes. However, this contention has remained speculative, and further studies are needed to better elucidate this relationship. We designed the present study to test the hypothesis that use of cognitive control modes would differ as a function of childhood fitness. We compared performance of lower-fit and higher-fit children on a modified AX-continuous performance task, commonly used to examine shifts in the use of proactive and reactive control, along with cue-P3 and contingent negative variation (CNV) of event-related brain potentials (ERPs). Results indicated that higher-fit children exhibited greater response accuracy for BX (non-target cue – target probe) relative to AY (target cue – non-target probe) trials, whereas lower-fit children had comparable response accuracies for AY and BX trials. Because enhanced BX performance and impaired AY performance may be attributed to the proactive use of context information, these results suggest that greater childhood fitness is associated with more effective utilization of proactive control. Higher-fit children also exhibited larger cue-P3 amplitude and smaller CNV amplitude for BX relative to AY trials, with no such effect of trial type in lower-fit children. These ERP results suggest that greater fitness is associated with more effective utilization of cue information and response preparation more appropriate to trial type, supporting the behavioral findings. The present study provides novel insights into the relationship between fitness and cognition from the perspective of cognitive control mode during task preparation.

The relationship between childhood aerobic fitness and brain functional connectivity

Several studies have indicated that higher levels of childhood aerobic fitness is associated with superior cognitive function, and this association is disproportionately observed in tasks requiring greater top-down control. We designed the current study to clarify the relationship between childhood fitness and top-down control in terms of functional connectivity among brain regions, by evaluating phase-locking values (PLVs), which is a measure of frequency-specific phase synchrony between electroencephalographic signals during a visual search task. Lower-fit and higher-fit children performed a visual search task that included feature search and conjunction search conditions. The conjunction search condition required greater top-down control to reduce interference from task-irrelevant distractors that shared a basic feature with the target. Results indicated that higher-fit children exhibited higher response accuracy relative to lower-fit children across search conditions. The results of PLVs showed that higher-fit children had greater functional connectivity for the conjunction relative to the feature search condition, whereas lower-fit children showed no difference in functional connectivity between search conditions. Furthermore, PLVs showed different time courses between groups; that is, higher-fit children sustained upregulation of top-down control throughout the task period, whereas lower-fit children transiently upregulated top-down control after stimulus onset and could not sustain the upregulation. These findings suggest that higher levels of childhood aerobic fitness is related to brain functional connectivity involved in the sustained upregulation of top-down control.

Aerobic Fitness Is Associated With Cognitive Control Strategy in Preadolescent Children

ABSTRACTThe authors used a conditional accuracy function (CAF) method to compute the mean accuracy of multiple reaction time 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.

The role of aerobic fitness in cortical thickness and mathematics achievement in preadolescent children.

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 (<30th percentile VO2max). Furthermore, cortical gray matter thinning in anterior and superior frontal areas was associated with superior arithmetic performance. Together, these data add to our knowledge of the biological markers of school achievement, particularly mathematics achievement, and raise the possibility that individual differences in aerobic fitness play an important role in cortical gray matter thinning during brain maturation. The establishment of predictors of academic performance is key to helping educators focus on interventions to maximize learning and success across the lifespan.

Greater aerobic fitness is associated with more efficient inhibition of task-irrelevant information in preadolescent children

A growing number of neuroelectric studies using event-related brain potentials have demonstrated that greater aerobic fitness is associated with superior cognitive functioning across the lifespan. However, empirical data regarding the association between fitness and attentional orienting is scarce, with no evidence in children, and the findings are inconclusive. We designed the present study to examine the relationship between aerobic fitness and involuntary attentional orientation to task-irrelevant information in preadolescent children. Lower-fit and higher-fit children performed a visual oddball task in which irregular (i.e., rule-violating) stimuli appeared as a task-irrelevant dimension, while measures of task performance and the P3a component elicited by the irregular stimuli were assessed. Analyses revealed that higher-fit children exhibited lower miss rates and smaller P3a amplitude relative to lower-fit children. These findings suggest that greater childhood fitness is associated with more efficient inhibition of task-irrelevant information.

From cognitive motor preparation to visual processing: The benefits of childhood fitness to brain health

The association between a fit body and a fit brain in children has led to a rise of behavioral and neuroscientific research. Yet, the relation of cardiorespiratory fitness on premotor neurocognitive preparation with early visual processing has received little attention. Here, 41 healthy, lower and higher fit preadolescent children were administered a modified version of the Eriksen flanker task while electroencephalography (EEG) and behavioral measures were recorded. Event-related potentials (ERPs) locked to the stimulus onset with an earlier than usual baseline (−900/−800ms) allowed investigation of both the usual post-stimulus (i.e., the P1, N1 and P2) as well as the pre-stimulus ERP components, such as the Bereitschaftspotential (BP) and the prefrontal negativity (pN component). At the behavioral level, aerobic fitness was associated response accuracy, with higher fit children being more accurate than lower fit children. Fitness-related differences selectively emerged at prefrontal brain regions during response preparation, with larger pN amplitude for higher than lower fit children, and at early perceptual stages after stimulus onset, with larger P1 and N1 amplitudes in higher relative to lower fit children. Collectively, the results suggest that the benefits of being aerobically fit appear at the stage of cognitive preparation prior to stimulus presentation and the behavioral response during the performance of a task that challenges cognitive control. Further, it is likely that enhanced activity in prefrontal brain areas may improve cognitive control of visuo-motor tasks, allowing for stronger proactive inhibition and larger early allocation of selective attention resources on relevant external stimuli.

Polychlorinated biphenyl exposure and glucose metabolism in 9-year-old Danish children.

Human exposure to polychlorinated biphenyls (PCBs) has been associated to type 2 diabetes in adults. We aimed to determine whether concurrent plasma PCB concentration was associated with markers of glucose metabolism in healthy children. Cross-sectional study of 771 healthy Danish third grade school children ages 8-10 years in the municipality of Odense were recruited in 1997 through a two-stage cluster sampling from 25 schools stratified according to location and socioeconomic character; 509 (9.7 ± 0.8 y, 53% girls) had adequate amounts available for PCB analyses. Fasting serum glucose and insulin were measured and a homeostasis assessment model of insulin resistance (HOMA-IR) and β-cell function (HOMA-B) calculated. Plasma PCB congeners and other persistent compounds were measured and ΣPCB calculated. PCBs were present in plasma at low concentrations, median, 0.19 μg/g lipid (interquartile range, 0.12-0.31). After adjustment for putative confounding factors, the second, third, fourth, and fifth quintiles of total PCB were significantly inversely associated with serum insulin (-14.6%, -21.7%, -18.9%, -23.1%, P trend < .01), compared with the first quintile, but not with serum glucose (P = .45). HOMA-IR and HOMA-B were affected in the same direction due to the declining insulin levels with increasing PCB exposure. Similar results were found for individual PCB congeners, for βHCB (hexachlorobenzen) and pp-DDE (dichlorodiphenyldichloroethylene). A strong inverse association between serum insulin and PCB exposure was found while fasting glucose remained within the expected narrow range. Our findings suggest that PCB may not exert effect through decreased peripheral insulin sensitivity, as seen in obese and low-fit children, but rather through a toxicity to β-cells. It remains to be demonstrated whether lower HOMA-B is caused by destruction of β-cell-reducing peripheral insulin resistance and thereby increase fasting glucose as previously found.

I. An introduction to the relation of physical activity to cognitive and brain health, and scholastic achievement.

The current pandemic of physical inactivity threatens both physical and cognitive health throughout the lifespan. This monograph describes the multidisciplinary study of aspects of childhood health and its relationship to cognitive and brain function, and scholastic performance. Specifically, we focus on physical activity and physical fitness along with nutrition and obesity; interconnected aspects of health that have declined over the past 30 years in children of industrialized nations. Although much emphasis has been placed on correcting physical aspects of these public health concerns, it is only more recently that attention has been paid to the relation between physical health and cognitive health among school age children. The monograph begins with an overview of current behavioral trends that compete with physical activity engagement and contribute to the failure to achieve the public health recommendations for physical activity among children in the United States. Following the epidemiological overview, the relation of childhood fitness to brain structure and function is examined among children with varying fitness levels. The observed dissimilarities between higher- and lower-fit children are discussed within the context of typical brain development. To broaden the scope of research presented herein, the relation of nutrient intake--among both undernourished and well-nourished children--and obesity on cognition and brain are discussed. Next, novel empirical data are presented from a correlational study that indicates a differential relation between childhood fitness and adiposity on various aspects of cognition. In an effort to provide a more comprehensive review, a later chapter is dedicated to describing a small body of literature investigating the relation of physical activity to special populations of children, including those with learning disorders. In doing so, practical applications as well as challenges and limitations of implementing physical activity into the lives of children with learning disabilities are described. Finally, a detailed review and historical analysis of the relation of physical activity to scholastic performance is provided. This translational chapter provides an important application of the laboratory findings to a real world setting in which children rely upon attention, memory, and learning for scholastic success. Accordingly, this monograph is directed toward timely and important public health issues related to chronic disease prevention as a function of childhood inactivity and obesity with the goal of linking health behaviors to cognitive and brain health, and scholastic performance.

Aerobic fitness is associated with greater white matter integrity in 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, 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, 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.

The influence of cardiorespiratory fitness on strategic, behavioral, and electrophysiological indices of arithmetic cognition in preadolescent children.

The current study investigated the influence of cardiorespiratory fitness on arithmetic cognition in forty 9–10 year old children. Measures included a standardized mathematics achievement test to assess conceptual and computational knowledge, self-reported strategy selection, and an experimental arithmetic verification task (including small and large addition problems), which afforded the measurement of event-related brain potentials (ERPs). No differences in math achievement were observed as a function of fitness level, but all children performed better on math concepts relative to math computation. Higher fit children reported using retrieval more often to solve large arithmetic problems, relative to lower fit children. During the arithmetic verification task, higher fit children exhibited superior performance for large problems, as evidenced by greater d' scores, while all children exhibited decreased accuracy and longer reaction time for large relative to small problems, and incorrect relative to correct solutions. On the electrophysiological level, modulations of early (P1, N170) and late ERP components (P3, N400) were observed as a function of problem size and solution correctness. Higher fit children exhibited selective modulations for N170, P3, and N400 amplitude relative to lower fit children, suggesting that fitness influences symbolic encoding, attentional resource allocation and semantic processing during arithmetic tasks. The current study contributes to the fitness-cognition literature by demonstrating that the benefits of cardiorespiratory fitness extend to arithmetic cognition, which has important implications for the educational environment and the context of learning.

The Influence of Childhood Aerobic Fitness on Learning and Memory

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.

Cognitively challenging physical activity benefits executive function in overweight children

This study tested the association between aerobic fitness and executive function and the impact of enhanced, cognitively challenging physical activity on executive function in overweight and lean children. Seventy children aged 9–10 years were assigned to either a 6-month enhanced physical education programme including cognitively demanding (open skill) activities or curricular physical education only. Pre- and post-intervention tests assessed aerobic capacity (Leger test) and two components of executive function: inhibition and working memory updating (random number generation task). Indices of inhibition and memory updating were compared in higher- and lower-fit children and intervention effects were evaluated as a function of physical activity programme (enhanced vs. curricular) and weight status (lean vs. overweight). Results showed better inhibition in higher- than lower-fit children, extending the existing evidence of the association between aerobic fitness and executive function to new aspects of children’s inhibitory ability. Overweight children had more pronounced pre- to post-intervention improvements in inhibition than lean children only if involved in enhanced physical education. Such intervention effects were not mediated by aerobic fitness gains. Therefore, the cognitive and social interaction challenges inherent in open skill tasks, even though embedded in a low-dose physical activity programme, may represent an effective means to promote cognitive efficiency, especially in overweight children.

Effects of a lifestyle intervention on adiposity and fitness in overweight or low fit preschoolers (Ballabeina)

Overweight (OW) and low fit children represent cardiovascular high-risk groups. A multidimensional school-based lifestyle intervention performed in 652 preschoolers reduced skinfold thickness and waist circumference, and improved fitness, but did not affect BMI. The objective of this study is to examine whether the intervention was equally effective in OW (≥90th national percentile) and/or low fit (lowest sex- and age-adjusted quartile of aerobic fitness) children compared to their normal weight and normal fit counterparts. Cluster randomized controlled single blinded trial, conducted in 2008/09 in 40 randomly selected preschool classes in Switzerland. The intervention included a playful physical activity program and lessons on nutrition, media use and sleeps. Primary outcomes were BMI and aerobic fitness; secondary outcomes included sum of four skinfolds, waist circumference and motor agility. Modification of intervention effects by BMI-group and fitness-group was tested by interaction terms. Compared to their counterparts, OW children (n = 130) had more beneficial effects on waist circumference (p for interaction = 0.001) and low fit children (n = 154) more beneficial effects on all adiposity outcomes (p for interaction ≤0.03). The intervention effects on both fitness outcomes were not modified by BMI- or fitness-group (all p for interaction ≥0.2). Average intervention effect sizes for BMI were -0.12, -0.05, -0.26 and -0.02 kg/m(2) and for aerobic fitness were 0.40, 0.30, 0.12 and 0.36 stages for OW, normal weight, low fit and normal fit children, respectively. This multidimensional intervention was equally and for some adiposity measures even more effective in high-risk preschoolers and represents a promising option for these children.

Tracking of clustered cardiovascular disease risk factors from childhood to adolescence

Clustering of cardiovascular disease (CVD) risk factors has been found in children as young as 9 y of age. However, the stability of this clustering over the course of childhood has yet to be determined. The purpose of this study was to determine the tracking of clustered CVD risk from young school age through adolescence and to examine differences in tracking between levels of overweight/obesity and cardiorespiratory fitness (VO(2peak)). Beginning at 6 y, children (n = 434) were measured three times in 7 y. Anthropometrics, blood pressure, and VO(2peak) were measured. Fasting blood samples were analyzed for CVD risk factors. A clustered risk score (z-score) was constructed by adding sex-specific z-scores for blood pressure, homeostatic model assessment (HOMA-IR), triglyceride (TG), skinfolds, and negative values of high-density lipoprotein cholesterol (HDLc) and VO(2peak). Significant tracking coefficients were found between clustered z-score at all time intervals (r = 0.514, 0.559, and 0.381 between ages 6-9, 9-13, and 6-13 y, respectively, all P < 0.0001). Tracking was higher for low-fit children, whereas no clear pattern was found for different levels of body fat. We found that clustered z-score is a fairly stable characteristic through childhood. Implementation of preventive strategies could therefore start at early school age.

Role of Childhood Aerobic Fitness in Successful Street Crossing

Increased aerobic fitness is associated with improved cognition, brain health, and academic achievement during preadolescence. In this study, we extended these findings by examining the relationship between aerobic fitness and an everyday real-world task: street crossing. Because street crossing can be a dangerous multitask challenge and is a leading cause of injury in children, it is important to find ways to improve pedestrian safety. A street intersection was modeled in a virtual environment, and higher-fit (n = 13, 7 boys) and lower-fit (n = 13, 5 boys) 8- to 10-yr-old children, as determined by V˙O(2max) testing, navigated trafficked roads by walking on a treadmill that was integrated with an immersive virtual world. Child pedestrians crossed the street while undistracted, listening to music, or conversing on a hands-free cellular phone. Cell phones impaired street crossing success rates compared with the undistracted or music conditions for all participants (P = 0.004), a result that supports previous research. However, individual differences in aerobic fitness influenced these patterns (fitness × condition interaction, P = 0.003). Higher-fit children maintained street crossing success rates across all three conditions (paired t-tests, all P > 0.4), whereas lower-fit children showed decreased success rates when on the phone, relative to the undistracted (P = 0.018) and music (P = 0.019) conditions. The results suggest that higher levels of childhood aerobic fitness may attenuate the impairment typically associated with multitasking during street crossing. It is possible that superior cognitive abilities of higher-fit children play a role in the performance differences during complex real-world tasks.

Relationship of Body Fat and Cardiorespiratory Fitness with Cardiovascular Risk in Chinese Children

Backgrounds/ObjectivesCardiorespiratory fitness (CRF) and body fat play an important role in elevated risk for cardiovascular disease (CVD). However, the combined effects of CRF and obesity on metabolic health in Chinese children are unclear. The purpose of this study was to investigate the independent and combined associations between body fat, CRF, and CVD risk in Chinese schoolchildren.MethodsThe study subjects comprised 676 schoolchildren (392 boys and 284 girls, aged 9.6±0.7 yrs old) in Wuhan, China. Their body mass index (BMI), waist circumference (WC), CRF, blood pressure (BP), lipids, glucose, and pubertal status were assessed. Children were categorized into different groups based on their BMI, WC, and CRF using Chinese obesity cut-off points and CRF sex-specific median points. Metabolic Risk Score (MRS) was computed based on the standardized scores of BP, lipids, and glucose.ResultsMultiple linear regression models showed that, in the separate models, body fat was positively associated with MRS while CRF was inversely associated with MRS (p<0.001). However, when assessed simultaneously, only body fat had a significant association with MRS (p<0.001). In general, low-fit children had a lower MRS compared to their counterparts, and a significant difference between the two extreme groups was observed (low CRF and high fat vs. high CRF and low fat, p<0.001).ConclusionsThese findings suggest that both body fat and CRF should be considered when interpreting CVD risk in Chinese children, while body fat may be correlated with CVD risk more than CRF.

A functional MRI investigation of the association between childhood aerobic fitness and neurocognitive control

We used functional magnetic resonance imaging (fMRI) to examine brain activity of higher fit and lower fit children during early and late task blocks of a cognitive control flanker paradigm. For congruent trials, all children showed increased recruitment of frontal and parietal regions during the early block when the task was unfamiliar, followed by a decrease in activity in the later block. No within-group changes in congruent accuracy were reported across task blocks, despite a decline in performance across all participants, likely due to fatigue. During incongruent trials, only higher fit children maintained accuracy across blocks, coupled with increased prefrontal and parietal recruitment in the early task block and reduced activity in the later block. Lower fit children showed a decline in incongruent accuracy across blocks, and no changes in activation. We suggest that higher fit children are better at activating and adapting neural processes involved in cognitive control to meet and maintain task goals.

Aerobic fitness is associated with greater efficiency of the network underlying cognitive control in preadolescent children

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.