Cardiorespiratory fitness is a strong and consistent predictor of morbidity and mortality among adults: an overview of meta-analyses representing over 20.9 million observations from 199 unique cohort studies

OBJECTIVE

To examine and summarise evidence from meta-analyses of cohort studies that evaluated the predictive associations between baseline cardiorespiratory fitness (CRF) and health outcomes among adults.

DESIGN

Overview of systematic reviews.

DATA SOURCE

Five bibliographic databases were searched from January 2002 to March 2024.

RESULTS

From the 9062 papers identified, we included 26 systematic reviews. We found eight meta-analyses that described five unique mortality outcomes among general populations. CRF had the largest risk reduction for all-cause mortality when comparing high versus low CRF (HR=0.47; 95% CI 0.39 to 0.56). A dose-response relationship for every 1-metabolic equivalent of task (MET) higher level of CRF was associated with a 11%-17% reduction in all-cause mortality (HR=0.89; 95% CI 0.86 to 0.92, and HR=0.83; 95% CI 0.78 to 0.88). For incident outcomes, nine meta-analyses described 12 unique outcomes. CRF was associated with the largest risk reduction in incident heart failure when comparing high versus low CRF (HR=0.31; 95% CI 0.19 to 0.49). A dose-response relationship for every 1-MET higher level of CRF was associated with a 18% reduction in heart failure (HR=0.82; 95% CI 0.79 to 0.84). Among those living with chronic conditions, nine meta-analyses described four unique outcomes in nine patient groups. CRF was associated with the largest risk reduction for cardiovascular mortality among those living with cardiovascular disease when comparing high versus low CRF (HR=0.27; 95% CI 0.16 to 0.48). The certainty of the evidence across all studies ranged from very low-to-moderate according to Grading of Recommendations, Assessment, Development and Evaluations.

CONCLUSION

We found consistent evidence that high CRF is strongly associated with lower risk for a variety of mortality and incident chronic conditions in general and clinical populations.

Sleep Behaviors and the Shape of Subcortical Brain Structures in Children with Overweight/Obesity: A Cross-Sectional Study

OBJECTIVES

To examine the relationship between sleep and subcortical brain structures using a shape analysis approach.

METHODS

A total of 98 children with overweight/obesity (10.0 ± 1.1 y, 59 boys) were included in the cross-sectional analyses. Sleep behaviors (i.e., wake time, sleep onset time, total time in bed, total sleep time, sleep efficiency, and wakening after sleep onset) were estimated with wrist-worn accelerometers. The shape of the subcortical brain structures was acquired by magnetic resonance imaging. A partial correlation permutation approach was used to examine the relationship between sleep behaviors and brain shapes.

RESULTS

Among all the sleep variables studied, only total time in bed was significantly related to pallidum and putamen structure, such that those children who spent more time in bed had greater expansions in the right and left pallidum (211-751 voxels, all p's <0.04) and right putamen (1783 voxels, p = 0.03).

CONCLUSIONS

These findings suggest that more time in bed was related to expansions on two subcortical brain regions in children with overweight/obesity.

A systematic review and cluster analysis approach of 103 studies of high-intensity interval training on cardiorespiratory fitness

AIMS

This study aims to systematically review the systematic reviews and meta-analyses examining the effect of high-intensity interval training (HIIT) protocols on improving cardiorespiratory fitness (CRF) and to characterize the main patterns of HIIT modalities using clustering statistical procedures to examine their potential differences on improving CRF. Finally, we aimed to develop a comprehensive guideline for reporting HIIT protocols.

METHODS AND RESULTS

A systematic review was conducted on PubMed and Web of Science from their inception to 31 October 2022 for systematic reviews and meta-analysis aimed at assessing the effect of HIIT on CRF in the entire study population. The Assessment of Multiple Systematic Reviews 2 tool was used to evaluate the risk of bias of each review. Additionally, a principal component analysis testing the data adequacy for the factor solution through the Kaiser-Meyer-Olkin procedure test was conducted. Once the number of factors was identified, in order to identify data patterns according to the main characteristics of the HIIT protocols, a two-step cluster analysis was conducted. Nineteen systematic reviews and/or meta-analyses comprising 103 studies were included. Clustering of systematic reviews and meta-analyses identified three HIIT modalities ('HIIT-normal mixed', 'HIIT-long running', and 'HIIT-short cycling') underlying the interventions across the included studies. Similar effectiveness in increasing CRF among the three HIIT modalities was observed. Subgroup analyses showed no significant differences in CRF by sex, weight status, study design, and baseline physical activity level (P > 0.05), but differences were observed by age group, and exercise intensity indicator was used in the HIIT programmes (P < 0.05).

CONCLUSION

All three HIIT modalities produced significant improvements of CRF, although some modalities showed greater changes for some specific age groups or intensity indicators.

Effects of exercise on sleep in children with overweight/obesity: a randomized clinical trial

OBJECTIVE

The objective of this study was to examine the chronic effects of a 20-week exercise training program on device-assessed sleep and sleep-disordered breathing; and to determine whether participating in a session of the exercise program had effects on device-assessed sleep the subsequent night in children with overweight/obesity.

METHODS

A randomized clinical trial was conducted from November 2014 to June 2016. A total of 109 children (age 8-11 years) with overweight/obesity were randomized into an exercise training or control group. The exercise program included aerobic and resistance training 3 to 5 days/week. The control group participants continued their usual lifestyle. Device-assessed sleep outcomes were measured using wrist-worn actigraphy at baseline, in the middle of the exercise program (10th week), and at postintervention for seven consecutive days (24 h/day), and sleep-disordered breathing was measured via the Pediatric Sleep Questionnaire.

RESULTS

The exercise training program had a statistically significant effect on wake after sleep onset time (-10.8 min/day, -0.5 SDs, p = 0.040). No other chronic or acute effects (i.e., the subsequent night of attending a session of the exercise training program) were observed on the remaining sleep outcomes.

CONCLUSIONS

A 20-week exercise training program reduced wake after sleep onset time in children with overweight/obesity. Future randomized trials that include a sample of children with poor sleep health at baseline are needed to better appreciate the role of exercise in sleep health.

Which indices of cardiorespiratory fitness are more strongly associated with brain health in children with overweight/obesity?

PURPOSE

To compare the strength of associations between different indices of cardiorespiratory fitness (CRF) and brain health outcomes in children with overweight/obesity.

METHODS

Participants were 100 children aged 8-11 years. CRF was assessed using treadmill exercise test (peak oxygen uptake [V̇O2peak ], treadmill time, and V̇O2 at ventilatory threshold) and 20-metre shuttle run test (20mSRT, laps, running speed, estimated V̇O2peak using the equations by Léger et al., Mahar et al., and Matsuzaka et al.). Intelligence, executive functions, and academic performance were assessed using validated methods. Total gray matter and hippocampal volumes were assessed using structural MRI.

RESULTS

V̇O2peak /body mass (β = 0.18, 95% CI = 0.01-0.35) and treadmill time (β = 0.18-0.21, 95% CI = 0.01-0.39) were positively associated with gray matter volume. 20mSRT laps were positively associated with executive functions (β = 0.255, 95% CI = 0.089-0.421) and academic performance (β = 0.199-0.255, 95% CI = 0.006-0.421), and the running speed was positively associated with executive functions (β = 0.203, 95% CI = 0.039-0.367). Estimated V̇O2peak/Léger et al. was positively associated with intelligence, executive functions, academic performance, and gray matter volume (β = 0.205-0.282, 95% CI = 0.013-0.500). Estimated V̇O2peak/Mahar et al. and V̇O2peak/Matsuzaka et al. (speed) were positively associated with executive functions (β = 0.204-0.256, 95% CI = 0.031-0.436).

CONCLUSION

Although V̇O2peak is considered the gold standard indicator of CRF in children, peak performance (laps or running speed) and estimated V̇O2peak/Léger et al. derived from 20mSRT had stronger and more consistent associations with brain health outcomes than other indices of CRF in children with overweight/obesity.

A 20-week exercise program improved total body and legs bone mineral density in children with overweight or obesity: The ActiveBrains randomized controlled trial

OBJECTIVES

The aim of this study was to investigate the effect of a 20-week exercise program on bone mineral parameters in children with overweight or obesity.

DESIGN

Randomized controlled trial.

METHODS

This study took part from November 21, 2014, to June 30, 2016, in Granada, Spain. A secondary analysis of this parallel-group randomized controlled trial was performed with 77 children with overweight or obesity (9.9 ± 1.2, 65 % boys) who were randomly allocated to exercise or control group. All participants received lifestyle recommendations. The control group continued their usual routines, whereas the exercise group attended a minimum of 3 supervised 90-minute sessions/week of aerobic plus resistance training for 20 weeks. A whole-body scan by dual-energy X-ray absorptiometry was carried out to obtain body composition at total body less head, arms, lumbar spine, pelvis, and legs.

RESULTS

Participants in the exercise group acquired significantly higher total body aBMD (mean z-score [95 % confidence intervals, CI], 0.607 [0.522-0.692]) compared with the participants in the control group (mean z-score, 0.472 [0.388-0.556]); difference between groups, 0.135 standard deviations [95 % CI 0.015-0.255], and legs aBMD (mean z-score, 0.629 [0.550-0.708]); control group (mean z-score, 0.518 [0.440-0.596]); difference between groups, 0.111 [0.001-0.222]; all p < 0.05. There were no significant differences between exercise group and control group at the remaining evaluated regions (p > 0.05).

CONCLUSIONS

A 20-week non-specifically bone-targeted exercise program induced a small, yet significant, improvement on total body and legs aBMD in children with overweight or obesity. Future studies should investigate the interaction of weight status in the bone response to exercise programs.

TRIAL REGISTRATION

Prospectively registered in ClinicalTrials.gov Identifier: NCT02295072.

The effects of an exercise intervention on neuroelectric activity and executive function in children with overweight/obesity: The ActiveBrains randomized controlled trial

OBJECTIVE

To investigate whether a 20-week aerobic and resistance exercise program induces changes in brain current density underlying working memory and inhibitory control in children with overweight/obesity.

METHODS

A total of 67 children (10.00 ± 1.10 years) were randomized into an exercise or control group. Electroencephalography (EEG)-based current density (μA/mm2 ) was estimated using standardized low-resolution brain electromagnetic tomography (sLORETA) during a working memory task (Delayed non-matched-to-sample task, DNMS) and inhibitory control task (Modified flanker task, MFT). In DNMS, participants had to memorize four stimuli (Pokemons) and then select between two of them, one of which had not been previously shown. In MFT, participants had to indicate whether the centered cow (i.e., target) of five faced the right or left.

RESULTS

The exercise group had significantly greater increases in brain activation in comparison with the control group during the encoding phase of DNMS, particularly during retention of second stimuli in temporal and frontal areas (peak t = from 3.4 to 3.8, cluster size [k] = from 11 to 39), during the retention of the third stimuli in frontal areas (peak t = from 3.7 to 3.9, k = from 15 to 26), and during the retention of the fourth stimuli in temporal and occipital areas (peak t = from 2.7 to 4.3, k = from 13 to 101). In MFT, the exercise group presented a lower current density change in the middle frontal gyrus (peak t = -4.1, k = 5). No significant change was observed between groups for behavioral performance (p ≥ 0.05).

CONCLUSION

A 20-week exercise program modulates brain activity which might provide a positive influence on working memory and inhibitory control in children with overweight/obesity.

Active Commuting to School among Spanish Preschool Children: A Temporal Change Study between 2013 and 2017

BACKGROUND

Active commuting to school may increase the total daily physical activity and achieve health benefits among preschool children. Rates of active commuting to school among Spanish children and adolescents have been widely analysed, while the rates of active commuting to school among Spanish preschool children are unknown.

AIM

The main objective of this study was to examine the changes in the rates of active commuting to school in a sample of Spanish preschool children between 3 and 6 years old from 2013 to 2017.

METHODS

Data were found from five studies carried out across Spain. The study sample comprised 4787 preschool children (4.59 ± 0.77 years old; 51% males). The overall changes in active commuting to school were assessed using multilevel logistic regression analysis.

RESULTS

The rates of active commuting to school in Spanish preschool children are around 52%, and the active commuting to school rates have stayed stable throughout the period assessed (odds ratio from 0.40 to 0.58, all p > 0.05).

CONCLUSION

In preschool children, the present study obtained a favourable result on active commuting to school, showing a pattern stability in the examined period similar to other ages. It will be of great importance to promote this behaviour to obtain high levels of active commuting to school.

Effects of an Exercise Program on Cardiometabolic and Mental Health in Children With Overweight or Obesity: A Secondary Analysis of a Randomized Clinical Trial

Importance

Childhood obesity is a risk factor associated with type 2 diabetes, cardiovascular disease, and mental disorders later in life. Investigation of the parallel effects of a defined exercise program on cardiometabolic and mental health in children with overweight or obesity may provide new insights on the potential benefits of exercise on overall health.

Objective

To investigate the effects of a 20-week exercise program on cardiometabolic and mental health in children with overweight or obesity.

Design, Setting, and Participants

This secondary analysis of a parallel-group randomized clinical trial was conducted in Granada, Spain, from November 1, 2014, to June 30, 2016. Data analyses were performed between February 1, 2020, and July 14, 2022. Children with overweight or obesity aged 8 to 11 years were eligible, and the study was performed in an out-of-school context.

Intervention

The exercise program included 3 to 5 sessions/wk (90 min/session) of aerobic plus resistance training for 20 weeks. The wait-list control group continued with their usual routines.

Main Outcomes and Measures

Cardiometabolic outcomes as specified in the trial protocol included body composition (fat mass, fat-free mass, and visceral adipose tissue), physical fitness (cardiorespiratory, speed-agility, and muscular), and traditional risk factors (waist circumference, blood lipid levels, glucose levels, insulin levels, and blood pressure). Cardiometabolic risk score (z score) was calculated based on age and sex reference values for levels of triglycerides, inverted high-density lipoprotein cholesterol, and glucose, the mean of systolic and diastolic blood pressure, and waist circumference. An additional cardiometabolic risk score also included cardiorespiratory fitness. Mental health outcomes included an array of psychological well-being and ill-being indicators.

Results

The 92 participants included in the per-protocol analyses (36 girls [39%] and 56 boys [61%]) had a mean (SD) age of 10.0 (1.1) years. The exercise program reduced the cardiometabolic risk score by approximately 0.38 (95% CI, -0.74 to -0.02) SDs; decreased low-density lipoprotein cholesterol level by -7.00 (95% CI, -14.27 to 0.37) mg/dL (to convert to mmol/L, multiply by 0.0259), body mass index (calculated as weight in kilograms divided by height in meters squared) by -0.59 (95% CI, -1.06 to -0.12), fat mass index by -0.67 (95% CI, -1.01 to -0.33), and visceral adipose tissue by -31.44 (95% CI, -58.99 to -3.90) g; and improved cardiorespiratory fitness by 2.75 (95% CI, 0.22-5.28) laps in the exercise group compared with the control group. No effects were observed on mental health outcomes.

Conclusions and Relevance

In this secondary analysis of a randomized clinical trial, an aerobic plus resistance exercise program improved cardiometabolic health in children with overweight or obesity but had no effect on mental health.

Trial Registration

ClinicalTrials.gov Identifier: NCT02295072.

Differences in specific abdominal fat depots between metabolically healthy and unhealthy children with overweight/obesity: The role of cardiorespiratory fitness

OBJECTIVES

Fat depots localization has a critical role in the metabolic health status of adults. Nevertheless, whether that is also the case in children remains under-studied. Therefore, the aims of this study were: (i) to examine the differences between metabolically healthy (MHO) and unhealthy (MUO) overweight/obesity phenotypes on specific abdominal fat depots, and (ii) to further explore whether cardiorespiratory fitness plays a major role in the differences between metabolic phenotypes among children with overweight/obesity.

METHODS

A total of 114 children with overweight/obesity (10.6 ± 1.1 years, 62 girls) were included. Children were classified as MHO (n = 68) or MUO. visceral (VAT), abdominal subcutaneous (ASAT), intermuscular abdominal (IMAAT), psoas, hepatic, pancreatic, and lumbar bone marrow adipose tissues were measured by magnetic resonance imaging. Cardiorespiratory fitness was assessed using the 20 m shuttle run test.

RESULTS

MHO children had lower VAT and ASAT contents and psoas fat fraction compared to MUO children (difference = 12.4%-25.8%, all p < 0.035). MUO-unfit had more VAT and ASAT content than those MUO-fit and MHO-fit (difference = 34.8%-45.3%, all p < 0.044). MUO-unfit shows also greater IMAAT fat fraction than those MUO-fit and MHO-fit peers (difference = 16.4%-13.9% respectively, all p ≤ 0.001). In addition, MHO-unfit presented higher IMAAT fat fraction than MHO-fit (difference = 13.4%, p < 0.001). MUO-unfit presented higher psoas fat fraction than MHO-fit (difference = 29.1%, p = 0.008).

CONCLUSIONS

VAT together with ASAT and psoas fat fraction, were lower in MHO than in MUO children. Further, we also observed that being fit, regardless of metabolic phenotype, has a protective role over the specific abdominal fat depots among children with overweight/obesity.

Physical activity, sedentary time, and fitness in relation to brain shapes in children with overweight/obesity: Links to intelligence

OBJECTIVES

To examine the association between physical activity, sedentary time, and physical fitness with the shapes of subcortical brain structures in children with overweight/obesity. Further, we analyzed whether differences in the shapes of subcortical brain structures were related to intelligence. We hypothesized that those children with higher physical activity levels, lower sedentary time, and better fitness, would show greater expansion of the brain regions analyzed, and these expansions would be associated with higher intelligence.

STUDY DESIGN

100 children (10.0 ± 1.1 years, 40 girls) were included in the analyses. Physical activity and sedentary time were measured by accelerometry, and physical fitness was evaluated by a fitness battery. Shapes of subcortical brain structures were assessed by magnetic resonance imaging. Intelligence was measured by the Kaufmann Brief Intelligence test.

RESULTS

Physical activity was related to expansion of the right/left pallidum, right/left putamen, and right thalamus (p < 0.05). Higher sedentary time was related to contraction of the left thalamus and right nucleus accumbens (p < 0.05). Higher levels of cardiorespiratory fitness were associated with expansion of the right amygdala (p = 0.022). Greater strength in the upper-limb was related to expansion of the right/left pallidum and the left nucleus accumbens (p < 0.038), and contraction of the left amygdala (p = 0.030). Better speed-agility was associated with expansion of the left nucleus accumbens (p = 0.036). Physical activity- and fitness-related expansion of the right pallidum was associated with higher intelligence (all p < 0.05).

CONCLUSION

Physical activity, sedentary time, and physical fitness were significantly related to the shapes of subcortical brain structures, which in turn were related to intelligence in children with overweight/obesity.

Is higher physical fitness associated with better psychological health in young pediatric cancer survivors? A cross-sectional study from the iBoneFIT project

OBJECTIVE

To examine the associations of self-perceived and objectively-measured physical fitness with psychological well-being and distress indicators in young pediatric cancer survivors.

MATERIALS AND METHODS

A total of 116 participants (12.1 ± 3.3 years, 56.9% boys) from the iBoneFIT project participated in this cross-sectional study. Objectively-measured physical fitness (muscular fitness) was obtained by handgrip strength and standing long jump tests for the upper and lower body, respectively. Self-perceived physical fitness was obtained by the International Fitness Scale (IFIS). Positive and negative affect were assessed by the positive affect schedule for children (PANAS-C), happiness by Subjective Happiness Scale (SHS), optimism by Life Orientation Test-Revised (LOT-R), self-esteem by the Rosenberg Self-Esteem Scale (RSE), anxiety by State-Trait Anxiety Inventory for Children (STAIC-R), and depression by Children Depression Inventory (CDI). Multiple linear regressions adjusted by key covariates were performed to analyze associations.

RESULTS

No associations were found between objectively-measured muscular fitness and any of the psychological well-being and distress indicators (p > 0.05). Self-perceived overall fitness and flexibility were positively associated with positive affect (β ≥ 0.258, p < 0.05). Self-perceived cardiorespiratory fitness, speed/agility, and flexibility were negatively associated with depression (β ≥ -0.222, p < 0.05). Finally, self-perceived cardiorespiratory fitness was also negatively associated with anxiety and negative affect (β ≥ -0.264, p < 0.05).

CONCLUSIONS

Perceived physical fitness, but not objectively physical fitness, seems to be inversely related to psychological distress variables and to less extent positively related to psychological well-being. The findings from this study highlight the importance of promoting self-perceived fitness in the pediatric oncology population.

A new set of estimated cardiorespiratory fitness equations are associated with cognitive performance in older adults

This study aimed to develop new equations to estimate cardiorespiratory fitness specifically for older adults and, secondly, to analyze the associations of cardiorespiratory fitness, both objectively measured and estimated using new equations, with cognitive performance. Ninety-two older adults (41 females, 65-75 years) from baseline data of a randomized controlled trial were analyzed ("ClinicalTrials.gov" Identifier: NCT03923712). Participants completed 4 measurement sessions including (i) physiological and health indicators in a laboratory setting, (ii) field-based fitness tests, (iii) sociodemographic and physical activity questionnaires, and (iv) a battery of neuropsychological tests to evaluate cognitive performance. The main findings were as follows: (i) a set of new equations with good predictive value for estimated cardiorespiratory fitness were developed (74-87%), using different scenarios of complexity and/or equipment requirements, and (ii) higher estimated cardiorespiratory fitness, even using its simplest equation (eCRF =  - 1261.99 + 1.97 × 6 min walking test (m) + 1.12 × bioimpedance basal metabolic rate (kcal/day) + 5.25 × basal heart rate (bpm)), was associated with better cognitive performance evaluated by several neuropsychological tests (i.e., language, cognitive flexibility, fluency, attention, and working memory), similar to using objectively measured cardiorespiratory fitness. In summary, a new set of estimated cardiorespiratory fitness equations have been developed with predictive values ranging from 74 to 87% that could be used based on necessity, availability of equipment, resources, or measurement context. Moreover, similar to objectively measured cardiorespiratory fitness, this measure of estimated cardiorespiratory fitness was positively associated with performance on language, fluency, cognitive flexibility, attention, and working memory, independently of sex, age, and education level.

Top 10 International Priorities for Physical Fitness Research and Surveillance Among Children and Adolescents: A Twin-Panel Delphi Study

BACKGROUND

The measurement of physical fitness has a history that dates back nearly 200 years. Recently, there has been an increase in international research and surveillance on physical fitness creating a need for setting international priorities that could help guide future efforts.

OBJECTIVE

This study aimed to produce a list of the top 10 international priorities for research and surveillance on physical fitness among children and adolescents.

METHODS

Using a twin-panel Delphi method, two independent panels consisting of 46 international experts were identified (panel 1 = 28, panel 2 = 18). The panel participants were asked to list up to five priorities for research or surveillance (round 1), and then rated the items from their own panel on a 5-point Likert scale of importance (round 2). In round 3, experts were asked to rate the priorities identified by the other panel.

RESULTS

There was strong between-panel agreement (panel 1: r_s = 0.76, p < 0.01; panel 2: r_s = 0.77, p < 0.01) in the priorities identified. The list of the final top 10 priorities included (i) "conduct longitudinal studies to assess changes in fitness and associations with health". This was followed by (ii) "use fitness surveillance to inform decision making", and (iii) "implement regular and consistent international/national fitness surveys using common measures".

CONCLUSIONS

The priorities identified in this study provide guidance for future international collaborations and research efforts on the physical fitness of children and adolescents over the next decade and beyond.

Criterion-Related Validity of Field-Based Methods and Equations for Body Composition Estimation in Adults: A Systematic Review

PURPOSE OF REVIEW

Overweight and obesity are associated to health prognosis. Therefore, body composition assessment is an important health outcome, especially in adult population. We analyzed the criterion-related validity of existing field-based methods and equations for body composition estimation in adults aged 19-64 years.

RECENT FINDINGS

One hundred studies met inclusion criteria. The field-based methods, waist circumference (WC), body adiposity index (BAI), and body mass index (BMI) are valid to indicate body adiposity. Likewise, several equations, including the classical Durnin/Womersley equation, Jackson/Pollock equation (males), and Jackson, Pollock, and Ward equation (females), are valid to estimate total body fat mass or body fat percentage. Anthropometric field methods can provide a simple, quick, and easy informative indicators of adiposity in adults. Classical equations, such as Durnin/Womersley equation, Jackson/Pollock equation, and Jackson, Pollock, and Ward equation, are still valid to estimate total body fat mass or body fat percentage in adult population. When choosing estimation equations, specific population characteristics, such as age, weight status, or race ethnicity, should be taken into account. (Trial Registration: Registered on PROSPERO (CRD42020194272)).

Effects of a Family-Based Lifestyle Intervention Plus Supervised Exercise Training on Abdominal Fat Depots in Children With Overweight or Obesity: A Secondary Analysis of a Nonrandomized Clinical Trial

IMPORTANCE

Excess abdominal fat is a major determinant in the development of insulin resistance and other metabolic disorders. Increased visceral adipose tissue (VAT) seems to precede the development of insulin resistance and is therefore a prime target of childhood lifestyle interventions aimed at preventing diabetes.

OBJECTIVES

To examine the effect of added exercise to a family-based lifestyle intervention program designed to reduce VAT plus subcutaneous (ASAT), intermuscular (IMAAT), and pancreatic (PAT) adipose tissue in children with overweight or obesity and to explore the effect of changes in VAT on insulin resistance.

DESIGN, SETTING, AND PARTICIPANTS

This 2-group, parallel-design clinical trial was conducted in Vitoria-Gasteiz, Spain. A total of 116 children with overweight or obesity participated and were assigned to a 22-week family-based lifestyle program (control group [n = 57]) or the same program plus an exercise intervention (exercise group [n = 59]). Data were collected between September 1, 2014, and June 30, 2017, and imaging processing for fat depot assessments and data analysis were performed between May 1, 2019, and February 12, 2021.

INTERVENTIONS

The compared interventions consisted of a family-based lifestyle and psychoeducation program (two 90-minute sessions per month) and the same program plus supervised exercise (three 90-minute sessions per week).

MAIN OUTCOMES AND MEASURES

The primary outcome of this study was the change in VAT between baseline and 22 weeks as estimated by magnetic resonance imaging. The secondary outcomes were changes in ASAT, IMAAT, and PAT. The effect of changes in VAT area on insulin resistance was also recorded.

RESULTS

The 116 participants included in the analysis (62 girls [53.4%]) had a mean (SD) age of 10.6 (1.1) years, and 67 (57.8%) presented with obesity. Significantly greater reductions were recorded for the exercise group in terms of reduction in VAT (-18.1% vs -8.5% for the control group; P = .004), ASAT (-9.9% vs -3.0%; P = .001), and IMAAT (-6.0% vs -2.6%; P = .02) fat fractions compared with the control group. Changes in VAT explained 87.6% of the improvement seen in insulin resistance (β = -0.102 [95% CI, -0.230 to -0.002]).

CONCLUSIONS AND RELEVANCE

These findings suggest that the addition of exercise to a lifestyle intervention program substantially enhanced the positive effects on abdominal fat depots in children with overweight or obesity. In addition, the reduction in VAT seemed to largely mediate the improvement of insulin sensitivity. These results highlight the importance of including exercise as part of lifestyle therapies aimed at treating childhood obesity and preventing the development of type 2 diabetes.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02258126.

Effect of a Multicomponent Intervention on Hepatic Steatosis Is Partially Mediated by the Reduction of Intermuscular Abdominal Adipose Tissue in Children With Overweight or Obesity: The EFIGRO Project

OBJECTIVE

In adults, there is evidence that improvement of metabolic-associated fatty liver disease (MAFLD) depends on the reduction of myosteatosis. In children, in whom the prevalence of MAFLD is alarming, this muscle-liver crosstalk has not been tested. Therefore, we aimed to explore whether the effects of a multicomponent intervention on hepatic fat is mediated by changes in intermuscular abdominal adipose tissue (IMAAT) in children with overweight/obesity.

RESEARCH DESIGN AND METHODS

A total of 116 children with overweight/obesity were allocated to a 22-week family-based lifestyle and psychoeducational intervention (control group, n = 57) or the same intervention plus supervised exercise (exercise group, n = 59). Hepatic fat percentage and IMAAT were acquired by MRI at baseline and at the end of the intervention.

RESULTS

Changes in IMAAT explained 20.7% of the improvements in hepatic steatosis (P < 0.05). Only children who meaningfully reduced their IMAAT (i.e., responders) had improved hepatic steatosis at the end of the intervention (within-group analysis: responders -20% [P = 0.005] vs. nonresponders -1.5% [P = 0.803]). Between-group analysis showed greater reductions in favor of IMAAT responders compared with nonresponders (18.3% vs. 0.6%, P = 0.018), regardless of overall abdominal fat loss.

CONCLUSIONS

The reduction of IMAAT plays a relevant role in the improvement of hepatic steatosis after a multicomponent intervention in children with overweight/obesity. Indeed, only children who achieved a meaningful reduction in IMAAT at the end of the intervention had a reduced percentage of hepatic fat independent of abdominal fat loss. Our findings suggest that abdominal muscle fat infiltration could be a therapeutic target for the treatment of MAFLD in childhood.

Effects of an Exercise Program on Brain Health Outcomes for Children With Overweight or Obesity: The ActiveBrains Randomized Clinical Trial

IMPORTANCE

Pediatric overweight and obesity are highly prevalent across the world, with implications for poorer cognitive and brain health. Exercise might potentially attenuate these adverse consequences.

OBJECTIVES

To investigate the effects of an exercise program on brain health indicators, including intelligence, executive function, academic performance, and brain outcomes, among children with overweight or obesity and to explore potential mediators and moderators of the main effects of exercise.

DESIGN, SETTING, AND PARTICIPANTS

All preexercise and postexercise data for this 20-week randomized clinical trial of 109 children aged 8 to 11 years with overweight or obesity were collected from November 21, 2014, to June 30, 2016, with neuroimaging data processing and analyses conducted between June 1, 2017, and December 20, 2021. All 109 children were included in the intention-to-treat analyses; 90 children (82.6%) completed the postexercise evaluation and attended 70% or more of the recommended exercise sessions and were included in per-protocol analyses.

INTERVENTIONS

All participants received lifestyle recommendations. The control group continued their usual routines, whereas the exercise group attended a minimum of 3 supervised 90-minute sessions per week in an out-of-school setting.

MAIN OUTCOMES AND MEASURES

Intelligence, executive function (cognitive flexibility, inhibition, and working memory), and academic performance were assessed with standardized tests, and hippocampal volume was measured with magnetic resonance imaging.

RESULTS

The 109 participants included 45 girls (41.3%); participants had a mean (SD) body mass index of 26.8 (3.6) and a mean (SD) age of 10.0 (1.1) years at baseline. In per-protocol analyses, the exercise intervention improved crystallized intelligence, with the exercise group improving from before exercise to after exercise (mean z score, 0.62 [95% CI, 0.44-0.80]) compared with the control group (mean z score, -0.10 [95% CI, -0.28 to 0.09]; difference between groups, 0.72 SDs [95% CI, 0.46-0.97]; P < .001). Total intelligence also improved significantly more in the exercise group (mean z score, 0.69 [95% CI, 0.48-0.89]) than in the control group (mean z score, 0.07 [95% CI, -0.14 to 0.28]; difference between groups, 0.62 SDs [95% CI, 0.31-0.91]; P < .001). Exercise also positively affected a composite score of cognitive flexibility (mean z score: exercise group, 0.25 [95% CI, 0.05-0.44]; control group, -0.17 [95% CI, -0.39 to 0.04]; difference between groups, 0.42 SDs [95% CI, 0.13-0.71]; P = .005). These main effects were consistent in intention-to-treat analyses and after multiple-testing correction. There was a positive, small-magnitude effect of exercise on total academic performance (mean z score: exercise group, 0.31 [95% CI, 0.18-0.44]; control group, 0.10 [95% CI, -0.04 to 0.24]; difference between groups, 0.21 SDs [95% CI, 0.01-0.40]; P = .03), which was partially mediated by cognitive flexibility. Inhibition, working memory, hippocampal volume, and other brain magnetic resonance imaging outcomes studied were not affected by the exercise program. The intervention increased cardiorespiratory fitness performance as indicated by longer treadmill time to exhaustion (mean z score: exercise group, 0.54 [95% CI, 0.27-0.82]; control group, 0.13 [95% CI, -0.16 to 0.41]; difference between groups, 0.42 SDs [95% CI, 0.01-0.82]; P = .04), and these changes in fitness mediated some of the effects (small percentage of mediation [approximately 10%-20%]). The effects of exercise were overall consistent across the moderators tested, except for larger improvements in intelligence among boys compared with girls.

CONCLUSIONS AND RELEVANCE

In this randomized clinical trial, exercise positively affected intelligence and cognitive flexibility during development among children with overweight or obesity. However, the structural and functional brain changes responsible for these improvements were not identified.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT02295072.

Does sleep-disordered breathing add to impairments in academic performance and brain structure usually observed in children with overweight/obesity?

Approximately 4-11% of children suffer from sleep-disordered breathing (SDB), and children with obesity are at increased risk. Both obesity and SDB have been separately associated with poorer brain health, yet whether SDB severity affects brain health in children with obesity remains unanswered. This study aimed to examine associations of SDB severity with academic performance and brain structure (i.e., total brain and gray and white matter volumes and gray matter volume in the hippocampus) in children with overweight/obesity. One hundred nine children aged 8-12 years with overweight/obesity were included. SDB severity and its subscales (i.e., snoring, daytime sleepiness, and inattention/hyperactivity) were evaluated via the Pediatric Sleep Questionnaire (PSQ), and academic performance was evaluated with the Woodcock-Muñoz standardized test and school grades. Brain structure was assessed by magnetic resonance imaging. SDB severity was not associated with academic performance measured by the standardized test (all |β|> 0.160, P > 0.076), yet it was associated with the school grade point average (β = -0.226, P = 0.007) and natural and social science grades (β = -0.269, P = 0.024). Intention/hyperactivity seemed to drive these associations. No associations were found between SDB severity and the remaining school grades (all β < -0.188, P > 0.065) or brain volumes (all P > 0.05).

CONCLUSION

Our study shows that SDB severity was associated with lower school grades, yet it was not associated with the standardized measurement of academic performance or with brain volumes in children with overweight/obesity. SDB severity may add to academic problems in children beyond the effects contributed by overweight/obesity status alone.

WHAT IS KNOWN

• Sleep-disordered breathing (SDB) may affect brain structure and academic performance in children. • Children with overweight/obesity are at higher risk for the development of SDB, yet the comorbid obesity-SDB relationship with brain health has not been investigated thus far.

WHAT IS NEW

• To our knowledge, this is the first study examining the associations of comorbid obesity-SDB severity with brain volumes and academic performance in children. • SDB symptoms may adversely affect academic performance at school in children with overweight/obesity, beyond the effects of weight status alone.

The effects of daily physical activity intervention on physical fitness in preschool children

The study aimed to determine the effects of 6 months daily physical activity on physical fitness in preschool children. A total of 72 children (36 boys) and 92 children (47 boys) composed the experimental (EG) and control group (CG), respectively. We used the PREFIT battery access physical fitness. In EG, participants had 45 minutes of organized physical activity 5 days per week. The CG continued their usual routine with 30 minutes of structured physical activity two times per week. The EG improved the mean performance of grip strength (η p2=0.08) and sit-ups in the 30s ( p2=0.16) to a significantly greater extent as compared to the CG. In boys, the improvements of mean performance of handgrip strength (η p2=0.13), 4x10m shuttle run η p2=0.09), standing long jump (η p2=0.05), sit-ups in 30s (η p2=0.17) were significantly greater in EG than in the CG. However, girls in EG only had significant improvements  in the sit-ups in the 30 s test compared to CG (η p2=0.14). Overall, our study shows that after 6 months of daily exercise programme, preschool children improved muscular strength compared to those peers allocated in the control group. No significant differences between groups were found in the remaining fitness components analysed.

Healthier Minds in Fitter Bodies: A Systematic Review and Meta-Analysis of the Association between Physical Fitness and Mental Health in Youth

BACKGROUND

Physical fitness is an important marker of current and future health status, yet the association between physical fitness and indicators of mental health in youth has not been systematically reviewed and meta-analyzed.

OBJECTIVE

The aim of this work was to systematically review and meta-analyze the association between physical fitness components (i.e. cardiorespiratory fitness, muscular fitness, speed-agility, flexibility and fitness composite) and mental health indicators (i.e. psychological well-being and psychological ill-being) in preschoolers, children and adolescents.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Systematic searches were conducted in PubMed, Web of Science and Scopus from database inception to May 2020.

ELIGIBILITY CRITERIA

Studies (cross-sectional, longitudinal and intervention designs) were included if they measured at least one physical fitness component and one mental health indicator in healthy youth (2-18 years).

RESULTS

A total of 58 unique studies (52 cross-sectional, 4 longitudinal and 4 intervention studies) met all eligibility criteria and were included. There was a significant positive overall association between physical fitness and mental health in children and adolescents (pooled r = 0.206, p < 0.001). We found suggestive evidence of moderation by age group, fitness components and socioeconomic status (all p < 0.08). No relevant studies focusing on preschoolers were identified. Evidence based on longitudinal and intervention studies was limited.

CONCLUSION

We observed a small to medium sized positive association between physical fitness and overall mental health in youth. However, as the majority of studies were cross-sectional, additional longitudinal and intervention studies are needed to provide evidence of causation.

TRIAL REGISTRATION

PROSPERO registration number CRD42017080005.

Calibration and Cross-Validation of Accelerometer Cut-Points to Classify Sedentary Time and Physical Activity from Hip and Non-Dominant and Dominant Wrists in Older Adults

Accelerometers' accuracy for sedentary time (ST) and moderate-to-vigorous physical activity (MVPA) classification depends on accelerometer placement, data processing, activities, and sample characteristics. As intensities differ by age, this study sought to determine intensity cut-points at various wear locations people more than 70 years old. Data from 59 older adults were used for calibration and from 21 independent participants for cross-validation purposes. Participants wore accelerometers on their hip and wrists while performing activities and having their energy expenditure measured with portable calorimetry. ST and MVPA were defined as ≤1.5 metabolic equivalents (METs) and ≥3 METs (1 MET = 2.8 mL/kg/min), respectively. Receiver operator characteristic (ROC) analyses showed fair-to-good accuracy (area under the curve [AUC] = 0.62-0.89). ST cut-points were 7 mg (cross-validation: sensitivity = 0.88, specificity = 0.80) and 1 count/5 s (cross-validation: sensitivity = 0.91, specificity = 0.96) for the hip; 18 mg (cross-validation: sensitivity = 0.86, specificity = 0.86) and 102 counts/5 s (cross-validation: sensitivity = 0.91, specificity = 0.92) for the non-dominant wrist; and 22 mg and 175 counts/5 s (not cross-validated) for the dominant wrist. MVPA cut-points were 14 mg (cross-validation: sensitivity = 0.70, specificity = 0.99) and 54 count/5 s (cross-validation: sensitivity = 1.00, specificity = 0.96) for the hip; 60 mg (cross-validation: sensitivity = 0.83, specificity = 0.99) and 182 counts/5 s (cross-validation: sensitivity = 1.00, specificity = 0.89) for the non-dominant wrist; and 64 mg and 268 counts/5 s (not cross-validated) for the dominant wrist. These cut-points can classify ST and MVPA in older adults from hip- and wrist-worn accelerometers.

Distinct whole-blood transcriptome profile of children with metabolic healthy overweight/obesity compared to metabolic unhealthy overweight/obesity

BACKGROUND

Youth populations with overweight/obesity (OW/OB) exhibit heterogeneity in cardiometabolic health phenotypes. The underlying mechanisms for those differences are still unclear. This study aimed to analyze the whole-blood transcriptome profile (RNA-seq) of children with metabolic healthy overweight/obesity (MHO) and metabolic unhealthy overweight/obesity (MUO) phenotypes.

METHODS

Twenty-seven children with OW/OB (10.1 ± 1.3 years, 59% boys) from the ActiveBrains project were included. MHO was defined as having none of the following criteria for metabolic syndrome: elevated fasting glucose, high serum triglycerides, low high-density lipoprotein-cholesterol, and high systolic or diastolic blood pressure, while MUO was defined as presenting one or more of these criteria. Inflammatory markers were additionally determined. Total blood RNA was analyzed by 5'-end RNA-sequencing.

RESULTS

Whole-blood transcriptome analysis revealed a distinct pattern of gene expression in children with MHO compared to MUO children. Thirty-two genes differentially expressed were linked to metabolism, mitochondrial, and immune functions.

CONCLUSIONS

The identified gene expression patterns related to metabolism, mitochondrial, and immune functions contribute to a better understanding of why a subset of the population remains metabolically healthy despite having overweight/obesity.

IMPACT

A distinct pattern of whole-blood transcriptome profile (RNA-seq) was identified in children with metabolic healthy overweight/obesity (MHO) compared to metabolic unhealthy overweight/obesity (MUO) phenotype. The most relevant genes in understanding the molecular basis underlying the MHO/MUO phenotypes in children could be: RREB1, FAM83E, SLC44A1, NRG1, TMC5, CYP3A5, TRIM11, and ADAMTSL2. The identified whole-blood transcriptome profile related to metabolism, mitochondrial, and immune functions contribute to a better understanding of why a subset of the population remains metabolically healthy despite having overweight/obesity.

Association between Mediterranean Dietary Pattern and Breakfast Quality with Physical Fitness in School Children: The HIIT Project

Dietary habits have been linked with health in childhood. However, few studies have examined the association between healthy dietary patterns and physical fitness. Therefore, the aim of this study was to examine the associations of adherence to the Mediterranean dietary pattern (MDP) and breakfast quality with physical fitness in children. Further to this, we examined the role of physical activity in these associations. A total of 175 children (86 girls, 9.7 ± 0.3 years) participated. Adherence to MDP and breakfast quality were assessed by the KIDMED questionnaire and 24 h recall, respectively. Cardiorespiratory fitness, muscular strength, and speed–agility were assessed. Physical activity was evaluated by wrist-worn accelerometers. Greater adherence to the MDP was related with higher cardiorespiratory fitness, lower-limbs muscular strength, and speed–agility (all β ≥ 0.189, all p ≤ 0.02). No significant associations were observed between breakfast quality and physical fitness (all p > 0.05). However, all the significant associations disappeared after adjusting for physical activity (all p > 0.05). Our study sheds light on the relevance of adhering to the MDP over physical fitness in school children. However, there is no association between breakfast quality and physical fitness. Furthermore, physical activity seems to explain, at least partially, these findings.

Changes in lifestyle behaviours during the COVID-19 confinement in Spanish children: A longitudinal analysis from the MUGI project

BACKGROUND

Home confinement during the COVID-19 pandemic could have affected lifestyle behaviours of children, however evidence about it is emerging and yet scarce.

OBJECTIVES

To examine the effects of the COVID-19 confinement on lifestyle behaviours in Spanish children, and to assess the influence of social vulnerabilities on changes in lifestyle behaviours.

METHODS

Physical activity (PA), screen time, sleep time, adherence to the Mediterranean diet (KIDMED) and sociodemographic information were longitudinally assessed before (N = 291, 12.1 ± 2.4 years, 47.8% girls) and during the COVID-19 confinement (N = 113, 12.0 ± 2.6 years, 48.7% girls) by online questionnaires.

RESULTS

During the COVID-19 confinement, PA (-91 ± 55 min/d, P < .001) and screen time (±2.6 h/d, P < .001) worsened, whereas the KIDMED score improved (0.5 ± 2.2 points, P < .02). The decrease of PA was higher in children with mother of non-Spanish origin (-1.8 ± 0.2 vs -1.5 ± 0.1 h/d, P < .04) or with non-university studies (-1.7 ± 0.1 vs -1.3 ± 0.1 h/d, P < .005) in comparison to their counterparts.

CONCLUSION

This study evidence the negative impact of the COVID-19 confinement on PA levels and sedentary behaviours of Spanish children. These findings should be taken into account to design and implement public health strategies for preserving children´s health during and after the pandemic, particularly, in children with social vulnerabilities.

Association of Cardiorespiratory Fitness with Achievement Motivation in Physical Education in Adolescents

Cardiorespiratory fitness is an important health marker in adolescents. Thus, examining the relation between cardiorespiratory fitness and motivation should be important to increase health-related behaviors. This study aimed to describe adolescents' cardiorespiratory fitness and motivation by gender and to analyze the association between two cardiorespiratory fitness tests (original and with music) and motivation. A total of 341 adolescents (14.2 ± 1.5 years, 52.2% girls) participated in this study. Cardiorespiratory fitness was assessed using the 20 m shuttle run and its adaptation with music. Motivation was assessed though the "Achievement Motivation towards Physical Education" questionnaire. Boys presented with higher cardiorespiratory fitness and motivation (all, p < 0.05). Yet, when classifying fit and unfit groups, a higher percentage of girls were considered fit compared to boys (85.8% vs. 74.5%). A higher level of cardiorespiratory fitness (stages) and VO₂max were associated with a higher level of motivation (self-perceived competence and compared competence) and lower anxiety (all p < 0.05). These associations with motivation were stronger when the music was present in the test. In this sense, including music in activities focused on cardiorespiratory fitness could increase the cardiorespiratory fitness performance and motivation, especially in girls. It should be important to increase adolescents' cardiorespiratory fitness levels in order to increase motivation in physical education lessons and to include more motivational activities in order to achieve higher performance.

Relationship between fatness, physical fitness, and academic performance in normal weight and overweight schoolchild handball players in Qatar State

The aim of this study was to examine the correlation between physiological parameters (namely fatness and physical fitness) with academic performance (namely mathematics and science grade point average [GPA]) in normal weight and overweight schoolchild handball players. Thirty-six young male team handball players (age: 9±1 years; body mass: 45.5±14.2 kg; height: 1.38±9.1 m; body fat: 19.7±5.6%) at the highest national league for their age group participated. Anthropometry was examined by measuring body mass, body fat percentage (%BF), and body mass index (BMI). Fitness testing included the Yo-Yo Intermittent Recovery Test (level 1), squat jumps (SJ) and counter-movement jumps (CMJ), and upper-limb throwing performance (2 kg medicine ball seated front throw), a 15 m sprint test, and a T-half test for change-of-direction (COD) ability. Academic performance was evaluated through school records of grade point average (GPA) of mathematics and science. BMI was negatively correlated with science GPA (r = -0.57, p<0.001) and mathematics GPA (r = -0.39, p<0.001). Significant correlations between Yo-Yo test performance and science GPA (r = 0.73, p<0.001) and mathematics GPA (r = 0.66, p<0.001) existed. T-half test score (less time taken meant a superior performance) was negatively correlated with science GPA (r = 0.48, p = 0.003) and mathematics GPA (r = 0.63, p<0.01). In conclusion, fatness and physical fitness (except for the upper-muscular strength) were significantly related to academic performance in in schoolchild handball players. Based on results of this study, it seems pragmatic and appropriate to engage young schoolchild in physical activity as it associates with superior academic performance.

Associations of sleep with gray matter volume and their implications for academic achievement, executive function and intelligence in children with overweight/obesity

BACKGROUND

Children with overweight/obesity have poorer sleep and smaller gray matter volume (GMV) than normal-weight children. No studies have investigated the associations of objectively-assessed sleep and GMV in children with overweight/obesity, or their implications for academic and cognitive outcomes.

OBJECTIVES

To explore the associations of sleep behaviors with GMV in the whole brain and particularly the hippocampus as a region of interest independent of sedentary time (SED) and physical activity; and to assess whether GMV in the associated regions was related to academic achievement, executive function and intelligence quotient (IQ).

METHODS

Ninety-six children with overweight/obesity (10 ± 1 year) were included. Sleep behaviors were assessed with accelerometers. GMV was acquired by magnetic resonance imaging. Academic achievement, executive function and IQ were assessed with separate tests. Analyses were adjusted for sex, peak height velocity and parent education as well as SED and physical activity.

RESULTS

Earlier wake time, less time in bed, wakening after sleep onset (WASO) and WASO occurrences were associated with higher GMV in eight cortical brain regions (k:56-448, P's < .001). Longer total sleep time, higher sleep efficiency and less WASO time were associated with higher GMV in the right hippocampus (β:0.187-0.220, P's < .05). The inferior temporal, fusiform, supramarginal, and postcentral gyri, the superior parietal cortex, precuneus and hippocampus associated with academic achievement and/or IQ. Associations remained after adjustments for SED and physical activity.

CONCLUSIONS

Sleep behaviors are associated with GMV in multiple cortical regions including the right hippocampus in children with overweight/obesity, which in turn, were associated with academic achievement and IQ.

Effects of School-Based Exercise and Nutrition Intervention on Body Composition and Physical Fitness in Overweight Adolescent Girls

Regular exercise during school hours is encouraged since childhood obesity has reached epidemic proportions. Moreover, a great majority of adolescents do not meet the recommendations for moderate-to-vigorous physical activity. The present study aimed to determine the effects of school-based high-intensity interval training (HIIT) and nutrition intervention on body composition and physical fitness in overweight adolescent girls. Forty-eight girls were included in the study, of whom 24 (age = 15.5 ± 0.7 years) were randomized to a experimental group (EXP) (HIIT and nutrition intervention school-based program) and 24 (age = 15.7 ± 0.6 years) to a control group (CON) that maintained their usual physical education activities. HIIT consisted of 10 stations of own bodyweight exercise and was done three times per week for eight weeks. Moreover, the EXP participated in the nutrition program led by a nutritionist two times a week. Apart from body composition assessment, participants performed countermovement jump (CMJ), medicine ball throw, hand-grip test, and Yo-Yo Intermittent Recovery Level 1 Test (YYIRT1). A significant effect of group (EXP vs. CON) x time (pre vs. post) interaction was observed for weight [F(1,44) = 7.733; p = 0.008], body mass index [F(1,44) = 5.764; p = 0.020], body fat (in kg) [F(1,44) = 17.850; p < 0.001], and body fat (in %) [F(1,44) = 18.821; p < 0.001]. Moreover, a significant interaction was observed for the medicine ball throw [F(1,44) = 27.016; p < 0.001] and YYIRT1 [F(1,44) = 5.439; p = 0.024]. A significant main effect for time was found for hand grip [F(1,44) = 9.300; p = 0.004] and CMJ [F(1,44) = 12.866; p = 0.001].The present study has demonstrated that just eight weeks school-based HIIT and nutrition intervention, including three sessions a week, can improve body composition and muscular and physical aerobic performance in overweighted adolescent girls.

Smartphone App (2kmFIT-App) for Measuring Cardiorespiratory Fitness: Validity and Reliability Study

BACKGROUND

There is strong evidence suggesting that higher levels of cardiorespiratory fitness (CRF) are associated with a healthier metabolic profile, and that CRF can serve as a powerful predictor of morbidity and mortality. In this context, a smartphone app based on the 2-km walk test (UKK test) would provide the possibility to assess CRF remotely in individuals geographically distributed around a country or continent, and even between continents, with minimal equipment and low costs.

OBJECTIVE

The overall aim of this study was to evaluate the validity and reliability of 2kmFIT-App developed for Android and iOS mobile operating systems to estimate maximum oxygen consumption (VO2max) as an indicator of CRF. The specific aims of the study were to determine the validity of 2kmFIT-App to track distance and calculate heart rate (HR).

METHODS

Twenty participants were included for field-testing validation and reliability analysis. The participants completed the UKK test twice using 2kmFIT-App. Distance and HR were measured with the app as well as with accurate methods, and VO2max was estimated using the UKK test equation.

RESULTS

The validity results showed the following mean differences (app minus criterion): distance (-70.40, SD 51.47 meters), time (-0.59, SD 0.45 minutes), HR (-16.75, SD 9.96 beats/minute), and VO2max (3.59, SD 2.01 ml/kg/min). There was moderate validity found for HR (intraclass correlation coefficient [ICC] 0.731, 95% CI -0.211 to 0.942) and good validity found for VO2max (ICC 0.878, 95% CI -0.125 to 0.972). The reliability results showed the following mean differences (retest minus test): app distance (25.99, SD 43.21 meters), app time (-0.15, SD 0.94 seconds), pace (-0.18, SD 0.33 min/km), app HR (-4.5, 13.44 beats/minute), and app VO2max (0.92, SD 3.04 ml/kg/min). There was good reliability for app HR (ICC 0.897, 95% CI 0.742-0.959) and excellent validity for app VO2max (ICC 0.932, 95% CI 0.830-0.973). All of these findings were observed when using the app with an Android operating system, whereas validity was poor when the app was used with iOS.

CONCLUSIONS

This study shows that 2kmFIT-App is a new, scientifically valid and reliable tool able to objectively and remotely estimate CRF, HR, and distance with an Android but not iOS mobile operating system. However, certain limitations such as the time required by 2kmFIT-App to calculate HR or the temperature environment should be considered when using the app.

Sarcopenia, Diet, Physical Activity and Obesity in European Middle-Aged and Older Adults: The LifeAge Study

The revised European consensus defined sarcopenia as a progressive and generalized skeletal muscle disorder that is associated with an increased likelihood of adverse outcomes including falls, fractures, physical disability and mortality. The aim of this study was to determine the prevalence of sarcopenia and analyse the influence of diet, physical activity (PA) and obesity index as risk factors of each criteria of sarcopenia. A total of 629 European middle-aged and older adults were enrolled in this cross-sectional study. Anthropometrics were assessed. Self-reported PA and adherence to the Mediterranean diet were evaluated with the Global Physical Activity Questionnaire (GPAQ) and Prevention with Mediterranean Diet questionnaire (PREDIMED), respectively. The functional assessment included handgrip strength, lower body muscle strength, gait speed and agility/dynamic balance. Of the participants, 4.84% to 7.33% showed probable sarcopenia. Sarcopenia was confirmed in 1.16% to 2.93% of participants. Severe sarcopenia was shown by 0.86% to 1.49% of participants. Male; age group ≤65 years; lower body mass index (BMI); high levels of vigorous PA; and the consumption of more than one portion per day of red meat, hamburgers, sausages or cold cuts and/or preferential consumption of rabbit, chicken or turkey instead of beef, pork, hamburgers or sausages (OR = 0.126-0.454; all p < 0.013) resulted as protective factors, and more time of sedentary time (OR = 1.608-2.368; p = 0.032-0.041) resulted as a risk factor for some criteria of sarcopenia. In conclusion, age, diet, PA, and obesity can affect the risk of having low muscle strength, low muscle mass or low functional performance, factors connected with sarcopenia.

Feasibility and reliability of the Spanish version of the Youth Activity Profile questionnaire (YAP-Spain) in children and adolescents

Considerable public health efforts across the globe have focused on promoting physical activity (PA) and minimizing sedentary behaviour (SB) in youths. However, it is important to have valid, reliable and feasible methods to assess these behaviours in youths. The purpose of this study was to analyse the feasibility and reliability of the Spanish version of the previously validated Youth Activity Profile questionnaire (YAP) in children and adolescents. The YAP-S is a 15-item self-report instrument designed to capture PA and SB in youths. A total of 604 children (5-12 years old) and 346 adolescents (12-17 years old) filled out the questionnaire twice (14 days apart). Feasibility was evaluated through required time and number of misunderstood questions by participants. The test-retest reliability was examined using the weighted kappa coefficient (κ) and intraclass correlation coefficient. The average time to complete the questionnaire was 28.85 ± 14.28 and 12.24 ± 9.84 minutes in children and adolescents, respectively. No misunderstanding of questions was reported. The questionnaire showed an adequate reliability for activity at school, out-of-school and sedentary behaviours (k = 0.61-0.77; ICC = 0.77-0.89) in children and adolescents. The YAP-S might be considered a feasible and reliable questionnaire for assessing PA and SB in Spanish children and adolescents.

Activity-rest circadian pattern and academic achievement, executive function, and intelligence in children with obesity

This study aimed to analyze the associations of activity-rest pattern indicators with academic achievement, executive function, and intelligence and to explore whether these associations are mediated by the total gray matter volume among children with overweight/obesity. Ninety-five children (10 ± 1 year, 37 girls) with overweight/obesity (based on the World Obesity Federation body mass index cutoff points) were included in this cross-sectional study. Hip- and wrist-worn ActiGraph GT3X + accelerometers were used to assess the activity-rest pattern. Interdaily stability (IS), intradaily variability (IV), the mean value of the lowest 5 hours (L5), and the mean value of the maximum 10 hours (M10) of activity and their respective timing (TL5, TM10) were used as indicators of the activity-rest pattern throughout the day. Chronotype and social jetlag were used as indicators of circadian preference. Academic achievement, executive function, and intelligence were assessed with standardized tests. Gray matter volume was acquired by magnetic resonance imaging (MRI). IS was positively associated with executive function (β = 0.244, P = .014). IV was negatively associated with mathematics and academic applications (β: -0.211 to -0.238, P's ≤ .026). Later TM10 in the day was related to lower writing, academic skills, and intelligence (β: -0.229 to -0.271, P's ≤ .025). None of the associations found were mediated by gray matter volume. A non-fragmented and stable activity-rest pattern and earlier physical activity in the day were associated with better academic achievement, executive function, and intelligence in children with overweight/obesity. Further studies are required to corroborate or contrast our findings.

Physical fitness and brain source localization during a working memory task in children with overweight/obesity: The ActiveBrains project

The present study aims (i) to examine the association of physical fitness components (i.e., cardiorespiratory fitness, speed-agility, and muscular fitness) with brain current source density during working memory; and (ii) to examine whether fitness-related current density was associated to working memory performance and academic achievement. Eighty-five children with overweight/obesity aged 8-11 years participated in this cross-sectional study. Physical fitness components were assessed using the ALPHA test battery. Electroencephalography recordings were performed during a Delayed Non-Match-to-Sample task that assessed working memory. Brain source analysis was carried out using sLORETA to estimate regional current source density differences between high and low (H-L) working memory loads. Academic achievement was measured by the Spanish version of the Woodcock-Johnson III test battery. The main results showed that higher cardiorespiratory fitness was associated with higher H-L current density differences in frontal, limbic, and occipital regions during encoding and maintenance task's phases (β≥0.412, p ≤ 0.019). A limbic area was further related to better working memory performance (β=0.267, p = 0.005). During retrieval, higher cardiorespiratory fitness was also associated with higher current density in temporal regions (β=0.265, p = 0.013), whereas lower muscular fitness was associated with higher current density in frontal regions (β=-0.261, p = 0.016). Our results suggest that cardiorespiratory fitness, but not speed-agility nor muscular fitness, is positively associated with brain current source density during working memory processes in children with overweight/obesity. Fitness-related current density differences in limbic regions were associated with better working memory.

Effects of Exercise on Plantar Pressure during Walking in Children with Overweight/Obesity

PURPOSE

To investigate the effect of a 13-wk exercise program, based on "movement quality" and "multigames" work, on plantar pressure during walking in children with overweight/obesity (OW/OB).

METHOD

Seventy children (10.8 ± 1.2 yr, 58.5% girls) with OW/OB, as defined by the World Obesity Federation, were assigned to either a 13-wk exercise program (intervention group [EG]; n = 39), or to a usual lifestyle control group (CG) (n = 31). Children underwent assessments of basic anthropometry (weight and height) and plantar pressure during walking before and after the intervention period, recording plantar surface area (cm), maximum force (N), and force-time integrals (N·s).

RESULTS

After the 13-wk intervention period, the EG participants showed no significant change in total plantar surface area, while the CG participants experienced an increase in this variable (small effect size, -2.5 SD; P = 0.015). Compared with the GC participants, the EG participants showed a greater increase in the maximum force supported beneath the forefoot during walking at the end of the intervention period (small effect size, 0.33 SD; P = 0.012), specifically under the lateral and medial forefoot (both P < 0.05). Force-time changed similarly in both groups by the end of the intervention period (all regions P > 0.05).

CONCLUSIONS

These results suggest the exercise program led to positive structural and functional changes in plantar pressure during walking. The increase in maximum force supported by the forefoot in the EG children might indicate a change toward a more normal foot rollover pattern and a more adult gait.

Feasibility and concurrent validity of a cardiorespiratory fitness test based on the adaptation of the original 20 m shuttle run: The 20 m shuttle run with music

The purpose was to examine the feasibility of the 20m shuttle run test with music and to test its concurrent validity with the original 20m shuttle run test. A total of 386 adolescents (14.5±1.6 years old, 48.9% boys) participated in our study. A self-reported questionnaire was used to assess student's perception about the 20m shuttle run test with music and the original and to assess perceived exertion. Participants performed randomly the 20m shuttle run test with music and original two weeks apart. Average and maximum heart rate were monitored with heart rate monitors. The 20m shuttle run with music was a feasible test for measuring cardiorespiratory fitness in adolescents. The concurrent validity showed mean differences of 5.1±14.6 for shuttles, 0.3±0.8 km/h for speed, 0.5±4.1 for stages, and 1.5±4.1 for VO2max (all p<0.001) in favour of the 20m shuttle run with music vs. the original 20m shuttle run test. Mean difference for the rating of perceived exertion was 0.4±2.5 points (p=0.003). No significant difference was found between boys and girls. In conclusion, the 20mSRT-music is feasible and presents a good concurrent validity in adolescents, independently of the sex and it will be an alternative and good approach to assess cardiorespiratory fitness.

Physical fitness and white matter microstructure in children with overweight or obesity: the ActiveBrains project

Recent studies investigated the association of cardiorespiratory fitness with white matter microstructure in children, yet little work has explored to what extent other components of physical fitness (i.e., muscular or motor fitness) are associated with white matter microstructure. Indeed, this association has not been previously explored in children with overweight/obesity who present a different white matter development. Therefore, we aimed to examine associations between physical fitness components and white matter microstructure in children with overweight/obesity. In total, 104 (10.04 ± 1.15 years old; 43 girls) children were included in this cross-sectional study. Physical fitness was assessed using the ALPHA-fitness test battery. Fractional anisotropy (FA) and mean diffusivity were derived from diffusion tensor imaging (DTI). No association was found between physical fitness and global DTI metrics (all P > 0.082). Within individual tracts, all associations became non-significant when analyses were adjusted for multiple comparisons. Using the voxel-wise approach, we identified a small cluster in the left lateral frontal lobe where children with greater upper-body muscular fitness showed higher FA (P_{FWE-corrected} = 0.042). Although our results cannot conclude physical fitness is related to white matter microstructure in children with overweight/obesity; those findings indicate that the association of muscular fitness with white matter microstructure might be more focal on frontal areas of the brain, as opposed to global differences.

Sedentarism, Physical Activity, Steps, and Neurotrophic Factors in Obese Children

PURPOSE

This study aimed to examine the associations of sedentary time, physical activity (PA) and step-related behaviors with neurotrophic growth factors.

METHODS

A total of 97 children with overweight/obesity age 8 to 11 yr participated in this study. Sedentary time, PA, and steps were measured by GT3X+ accelerometers in hip and nondominant wrist. Estimates of light, moderate, vigorous, and moderate-to-vigorous PA (MVPA) were obtained. Steps per daytime, peak 60-, 30-, and 1-min cadence were computed. The time accumulated (min·d) in different cadence bands of steps was also computed from hip accelerometer. Plasma levels of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), and insulin growth factor-1 (IGF-1) were determined by the XMap technology (Luminex IS 100/200 system, Luminex Corporation, Austin, TX).

RESULTS

Light PA, moderate PA, MVPA, and the peak 60-min cadence were positively related with BDNF concentrations (all P < 0.05), and only light PA to VEGF (P = 0.048). No association was observed for IGF-1 (P > 0.05). The associations of light PA with BDNF and VEGF disappeared (all P > 0.05) after performing analyses with nondominant wrist-placement data. However, moderate PA and MVPA remained significantly associated with BDNF (both P < 0.05). The time accumulated in cadence bands of 40 to 59 steps per day and 60 to 79 steps per day (i.e., walking at slow pace) was positively associated with plasma BDNF (all P < 0.05).

CONCLUSIONS

In conclusion, PA is positively related to plasma BDNF, whereas no relationship was observed for VEGF or IGF-1. Higher amounts of time spent in slow walking cadence bands could increment BDNF levels. Exercise-based randomized controlled trials in children with overweight/obesity should be carried out to better understand the influence of PA behaviors on the neurotrophic factors.

Association Between Physical Fitness and Bone Strength and Structure in 3- to 5-Year-Old Children

BACKGROUND

The positive association between physical fitness and bone structure has been widely investigated in children and adolescents, yet no studies have evaluated this influence in young children (ie, preschoolers).

HYPOTHESIS

Fit children will present improved bone variables when compared with unfit children, and no sex-based differences will emerge in the sample.

STUDY DESIGN

Cross-sectional study.

LEVEL OF EVIDENCE

Level 3.

METHODS

Handgrip strength, standing long jump (SLJ), speed/agility, balance, and cardiorespiratory fitness (CRF) were assessed using the Assessing FITness levels in PREschoolers (PREFIT) test battery in 92 children (50 boys; age range, 3-5 years). A peripheral quantitative computed tomography scan was performed at 38% of the length of the nondominant tibia. Cluster analysis from handgrip strength, SLJ, speed/agility, and CRF was developed to identify fitness groups. Bone variables were compared between sexes and between cluster groups. The association between individual physical fitness components and different bone variables was also tested.

RESULTS

Three cluster groups emerged: fit (high values on all included physical fitness variables), strong (high strength values and low speed/agility and CRF), and unfit (low strength, speed/agility, and CRF). The fit group presented higher values than the strong and unfit groups for total and cortical bone mineral content, cortical area, and polar strength strain index (all P < 0.05). The fit group also presented a higher cortical thickness when compared with the unfit group (P < 0.05). Handgrip, SLJ, and speed/agility predicted all bone variables except for total and cortical volumetric bone mineral density. No differences were found for bone variables between sexes.

CONCLUSION

The results suggest that global fitness in preschoolers is a key determinant for bone structure and strength but not volumetric bone mineral density.

CLINICAL RELEVANCE

Physical fitness is a determinant for tibial bone mineral content, structure, and strength in very young children. Performing physical fitness tests could provide useful information related to bone health in preschoolers.

Associations of Sedentary Behaviour, Physical Activity, Cardiorespiratory Fitness and Body Composition with Risk of Sleep-Related Breathing Disorders in Children with Overweight/Obesity: A Cross-Sectional Study

The aim of this study was to examine the associations of sedentary behaviour, physical activity, cardiorespiratory fitness (CRF), and body composition parameters with risk of sleep-related breathing disorders (SRBD) in children with overweight/obesity. One-hundred and nine children (10.0 ± 1.1 years old, 45 girls) with overweight (n = 27) and obesity (n = 82) were included. Television viewing time was self-reported by using the Spanish adaptation of the "Youth Activity Profile" (YAP) questionnaire. Sedentary time and physical activity were measured with accelerometry. CRF was assessed with the 20-m shuttle-run test and body composition parameters with Dual-energy X-ray absorptiometry. SRBD were evaluated by using the Spanish version of the Pediatric Sleep Questionnaire. Television viewing time was positively associated with risk of SRBD (r = 0.222, p = 0.021). CRF was negatively correlated with risk of SRBD (r = -0.210, p = 0.030). Body composition parameters were positively associated with risk of SRBD (all p < 0.05), except fat mass index. Stepwise regression analyses showed that body mass index (BMI) explained the largest proportion of the variance in SRBD (r² = 0.063, p = 0.01) and television viewing time was the only one added after BMI (r² change = 0.048, p = 0.022). This study supports the notion that higher body weight status negatively influences risk of SRBD and adds that unhealthy behaviours could contribute to worsen SRBD, related to an increased risk of cardiovascular diseases. All the significant association observed in this manuscript were of small magnitude, indicating than other factors in addition to the one hereby studied contribute to explain the variance in SRBD.

Lean mass index is positively associated with white matter volumes in several brain regions in children with overweight/obesity

BACKGROUND

The relationship of obesity with grey and white matter volumes has been examined in several studies, and the results are decidedly mixed.

OBJECTIVE

To investigate the associations of body mass index (BMI), fat mass index (FMI) and lean mass index (LMI) with total and regional grey and white matter volumes.

METHODS

This is a cross-sectional study involving 100 children (60% boys) with overweight/obesity. T1-weighted images were acquired using magnetic resonance imaging. Dual energy X-ray absorptiometry was used to measure body composition. Separate hierarchical regression analyses were performed between predictor variables (BMI, FMI and LMI) and the total brain volumes including sex, years from peak height velocity and parental education as covariates. In addition, FMI was added as a covariate when LMI was the predictor and vice versa. Statistical analyses of imaging data were performed using three whole-brain voxel-wise multiple regression models and adjusted by the same covariates.

RESULTS

LMI was positively associated with white matter in numerous regions and to a lower extent, with grey matter regions. Further, the relationship between LMI, and grey and white matter regions was independent of FMI levels.

CONCLUSIONS

LMI seems to be a positive predictor of regional white matter volumes in children with overweight/obesity.

Step-Based Metrics and Overall Physical Activity in Children With Overweight or Obesity: Cross-Sectional Study

Background

Best-practice early interventions to increase physical activity (PA) in children with overweight and obesity should be both feasible and evidence based. Walking is a basic human movement pattern that is practical, cost-effective, and does not require complex movement skills. However, there is still a need to investigate how much walking—as a proportion of total PA level—is performed by children who are overweight and obese in order to determine its utility as a public health strategy.

Objective

This study aimed to (1) investigate the proportion of overall PA indicators that are explained by step-based metrics and (2) study step accumulation patterns relative to achievement of public health recommendations in children who are overweight and obese.

Methods

A total of 105 overweight and obese children (mean 10.1 years of age [SD 1.1]; 43 girls) wore hip-worn accelerometers for 7 days. PA volumes were derived using the daily average of counts per 15 seconds, categorized using standard cut points for light-moderate-vigorous PA (LMVPA) and moderate-to-vigorous PA (MVPA). Derived step-based metrics included volume (steps/day), time in cadence bands, and peak 1-minute, 30-minute, and 60-minute cadences.

Results

Steps per day explained 66%, 40%, and 74% of variance for counts per 15 seconds, LMVPA, and MVPA, respectively. The variance explained was increased up to 80%, 92%, and 77% by including specific cadence bands and peak cadences. Children meeting the World Health Organization recommendation of 60 minutes per day of MVPA spent less time at zero cadence and more time in cadence bands representing sporadic movement to brisk walking (ie, 20-119 steps/min) than their less-active peers.

Conclusions

Step-based metrics, including steps per day and various cadence-based metrics, seem to capture a large proportion of PA for children who are overweight and obese. Given the availability of pedometers, step-based metrics could be useful in discriminating between those children who do or do not achieve MVPA recommendations.

Trial Registration

ClinicalTrials.gov NCT02295072; https://clinicaltrials.gov/ct2/show/NCT02295072

The relative age effect on physical fitness in preschool children

The aim of the present study was to investigate the existence of a relative age effect (RAE) on physical fitness of preschoolers. Anthropometry and physical fitness were assessed in 3147 children (3-5 years old) using the PREFIT battery. Based on the birth year, participants were divided into 3year groups (3-, 4- and 5-years). Within each year group, 4quarter groups were created: quarter 1, preschoolers born from January to March; quarter 2, from April to June; quarter 3, from July to September; quarter 4, from October to December. The MANCOVA analysis revealed a main effect of year group (Wilks' λ = 0.383; F_10,5996 = 369.64; p < 0.001, η_p ² = 0.381) and of quarter (Wilks' λ = 0.874; F_15,8276.6 = 27.67; p < 0.001; η_p ² = 0.044) over the whole battery of tests. To the best of our knowledge, this is the first study to report the existence of RAE at the preschool stage. In general, performance improved as the relative age increased (i.e., those born in quarter 1 performed better than those in the other quarters). Individualization strategies should be addressed within the same academic year not only in elementary or secondary years but also in preschoolers.

Differences in Brain Volume between Metabolically Healthy and Unhealthy Overweight and Obese Children: The Role of Fitness

The aim of this study was to examine whether metabolically healthy overweight/obese children have greater global and regional gray matter volumes than their metabolically unhealthy peers. We further examined the association between gray matter volume and academic achievement, along with the role of cardiorespiratory fitness in these associations. A total of 97 overweight/obese children (10.0 ± 1.2 years) participated. We classified children as metabolically healthy/unhealthy based on metabolic syndrome cut-offs. Global and regional brain volumes were assessed by magnetic resonance imaging. Academic achievement was assessed using the Woodcock-Muñoz standardized test. Cardiorespiratory fitness was assessed by the 20 m shuttle run test. Metabolically healthy overweight/obese (MHO) children had greater regional gray matter volume compared to those who were metabolically unhealthy (MUO) (all p ≤ 0.001). A similar trend was observed for global gray matter volume (p = 0.06). Global gray matter volume was positively related to academic achievement (β = 0.237, p = 0.036). However, all the associations were attenuated or disappeared after adjusting for cardiorespiratory fitness (p > 0.05). The findings of the present study support that metabolically healthy overweight/obese children have greater gray matter volume compared to those that are metabolically unhealthy, which is in turn related to better academic achievement. However, cardiorespiratory fitness seems to explain, at least partially, these findings.

Fitness, physical activity and academic achievement in overweight/obese children

The aim of this study was to examine the associations of fitness and physical activity with academic achievement in children with overweight/obesity. A total of 106 (10.0 ± 1.1y, 61 boys) children participated. The fitness components were assessed by field and laboratory-based tests. Physical activity was measured via accelerometry. The academic achievement was assessed by a standardised test and school-grades. Field-based cardiorespiratory fitness was associated with language skills (ß-standardised- ranging from 0.281 to 0.365, p < 0.01). The field-based muscular strength was associated with grade point average, natural and social sciences, and foreign language (ß = 0.280-0.326, all p ≤ 0.01). Speed-agility was associated with some language-related skills (ß = 0.325-0.393, all p ≤ 0.01). The laboratory-based muscular strength also showed an association with mathematics skills (ß = 0.251-0.306, all p ≤ 0.01). Physical activity did not show significant association with academic achievement (p > 0.01). Overall, the significant associations observed for muscular strength and speed/agility were attenuated and disappeared in many cases after additional adjustments for body mass index and cardiorespiratory fitness, indicating that these associations are inter-dependent. Our study contributes by indicating that other fitness components apart from cardiorespiratory fitness, such as muscular strength and speed-agility, are positively associated with academic achievement. However, these associations appear to be dependent on body mass index and cardiorespiratory fitness.