Geir Kåre Resaland

Effects of physical activity on schoolchildren's academic performance : The Active Smarter Kids (ASK) cluster-randomized controlled trial

OBJECTIVE To investigate the effect of a seven-month, school-based cluster-randomized controlled trial on academic performance in 10-year-old children. METHODS In total, 1129 fifth-grade children from 57 elementary schools in Sogn og Fjordane County, Norway, were cluster-randomized by school either to the intervention group or to the control group. The children in the 28 intervention schools participated in a physical activity intervention between November 2014 and June 2015 consisting of three components: 1) 90min/week of physically active educational lessons mainly carried out in the school playground; 2) 5min/day of physical activity breaks during classroom lessons; 3) 10min/day physical activity homework. Academic performance in numeracy, reading and English was measured using standardized Norwegian national tests. Physical activity was measured objectively by accelerometry. RESULTS We found no effect of the intervention on academic performance in primary analyses (standardized difference 0.01-0.06, p>0.358). Subgroup analyses, however, revealed a favorable intervention effect for those who performed the poorest at baseline (lowest tertile) for numeracy (p=0.005 for the subgroup∗group interaction), compared to controls (standardized difference 0.62, 95% CI 0.19-1.07). CONCLUSIONS This large, rigorously conducted cluster RCT in 10-year-old children supports the notion that there is still inadequate evidence to conclude that increased physical activity in school enhances academic achievement in all children. Still, combining physical activity and learning seems a viable model to stimulate learning in those academically weakest schoolchildren.

The Andersen Aerobic Fitness Test: reliability and validity in 10-year-old children

Background High aerobic fitness is consistently associated with a favorable metabolic risk profile in children. Direct measurement of peak oxygen consumption (VO2peak) is often not feasible, thus indirect tests such as the Andersen test are required in many settings. The present study seeks to determine the reliability and validity of the Andersen test in 10-year-old children. Methods A total of 118 10-year-old children (67 boys and 51 girls) were recruited from one school and performed four VO2peak tests over three weeks: three Andersen tests (indirect) and one continuous progressive treadmill test (direct). Of these, 104 children provided valid data on all Andersen tests and 103 children also provided valid data on the direct treadmill test. Reliability and validity were assessed using Bland Altman plots and linear regression analysis. Results Bias (mean change) and random error (limits of agreement) were 26.7±125.2 m for test 2 vs. test 1 (p<.001 for mean difference) and 3.9±88.8 m for test 3 vs. test 2 (p = .514 for mean difference). The equation to estimate VO2peak suggested by Andersen et al. (2008) showed a poor fit in the present sample; thus, we suggest a new equation: VO2peak = 23.262+0.050*Andersen distance –3.858*gender –0.376*body weight (R2 = 0.61, standard error of the estimate = 5.69, p<.001, boys = 0, girls = 1). Conclusions The Andersen test provided reliable and valid data on a group level. However, a substantial degree of individual variability was found for estimates of VO2peak. Researchers should be aware of the amount of noise in indirect tests that estimate aerobic fitness.

New examination of the performance of the MetaMax I metabolic analyser with the Douglas-bag technique.

Abstract Purpose. To examine the performance of the MetaMax® I metabolic analyser of Cortex Biophysik, running a recent version of the software (MetaSoft v. 1.11.05), using the Douglas-bag method as reference. Experiments. First, 182 measurements of the maximal O2 uptake on school children were analysed both by a former version of the software (MetaMax Analysis) and by a recent version (MetaSoft). In further experiments, seven grown-up subjects of different fitness levels cycled for 5 min at constant powers between 50 and 350 W while the O2 uptake was measured simultaneously by the MetaMax I and the Douglas-bag method during the last minute of altogether 39 exercises. Results. The calculated maximal O2 uptake of the 182 school children was on average 3% lower when the data were reanalysed by MetaSoft than when analysed by the former version of the software. There was in addition a 2% variation. In further experiments on grown-up subjects the O2 uptake reported by the MetaMax I did not differ from that reported by the Douglas-bag system when data for all subjects were pooled, and the random error was 4%. However, the relationships differed slightly between the subjects (p = 0.005), and consequently the random error within each subject was 2–3%. The respiratory exchange ratio (R-value) reported by the MetaMax I differed systematically from that of the control method. However, a reliable R-value could be calculated from the instruments raw data. Conclusions. Our data suggest that the MetaMax I running MetaSoft reports unbiased values of the O2 uptake and with moderate random error.

Moderate-to-vigorous physical activity, but not sedentary time, predicts changes in cardiometabolic risk factors in 10-y-old children: the Active Smarter Kids Study

Background: Cross-sectional data have suggested an inverse relation between physical activity and cardiometabolic risk factors that is independent of sedentary time. However, little is known about which subcomponent of physical activity may predict cardiometabolic risk factors in youths.Objective: We examined the independent prospective associations between objectively measured sedentary time and subcomponents of physical activity with individual and clustered cardiometabolic risk factors in healthy children aged 10 y.Design: We included 700 children (49.1% males; 50.9% females) in which sedentary time and physical activity were measured with the use of accelerometry. Systolic blood pressure, waist circumference (WC), and fasting blood sample (total cholesterol, high-density lipoprotein cholesterol, triglycerides, glucose, fasting insulin) were measured with the use of standard clinical methods and analyzed individually and as a clustered cardiometabolic risk score standardized by age and sex (z score). Exposure and outcome variables were measured at baseline and at follow-up 7 mo later.Results: Sedentary time was not associated with any of the individual cardiometabolic risk factors or clustered cardiometabolic risk in prospective analyses. Moderate physical activity at baseline predicted lower concentrations of triglycerides (P = 0.021) and homeostatic model assessment for insulin resistance (P = 0.027) at follow-up independent of sex, socioeconomic status, Tanner stage, monitor wear time, or WC. Moderate-to-vigorous physical activity (P = 0.043) and vigorous physical activity (P = 0.028) predicted clustered cardiometabolic risk at follow-up, but these associations were attenuated after adjusting for WC.Conclusions: Physical activity, but not sedentary time, is prospectively associated with cardiometabolic risk in healthy children. Public health strategies aimed at improving childrens cardiometabolic profile should strive for increasing physical activity of at least moderate intensity rather than reducing sedentary time. This trial was registered at clinicaltrials.gov as NCT02132494.

Executive Functions Do Not Mediate Prospective Relations between Indices of Physical Activity and Academic Performance: The Active Smarter Kids (ASK) Study

Changes in cognitive function induced by physical activity have been proposed as a mechanism for the link between physical activity and academic performance. The aim of this study was to investigate if executive function mediated the prospective relations between indices of physical activity and academic performance in a sample of 10-year-old Norwegian children. The study included 1,129 children participating in the Active Smarter Kids (ASK) trial, followed over 7 months. Structural equation modeling (SEM) with a latent variable of executive function (measuring inhibition, working memory, and cognitive flexibility) was used in the analyses. Predictors were objectively measured physical activity, time spent sedentary, aerobic fitness, and motor skills. Outcomes were performance on national tests of numeracy, reading, and English (as a second language). Generally, indices of physical activity did not predict executive function and academic performance. A modest mediation effect of executive function was observed for the relation between motor skills and academic performance. Trial registration: Clinicaltrials.gov registry, trial registration number: NCT02132494.

Physical activity and cardiovascular risk factors in a 40- to 42-year-old rural Norwegian population from 1975-2010: repeated cross-sectional surveys.

BackgroundGeographical differences in cardiovascular diseases (CVD) have been observed among Norwegian counties. Better long-term health status and higher physical activity (PA) levels have been documented in the county of Sogn & Fjordane compared with other counties. However, recent trends in CVD risk factors have not been documented. The aim of this study was to investigate the secular trends in leisure time physical activity (LTPA) and other CVD risk factors over a 35-year period in a rural population of 40- to 42-year-olds in western Norway and to compare these trends with national trends.MethodsData from eight cross-sectional studies from 1975–2010 (n = 375,682) were obtained from questionnaires and physical examinations and were analyzed using mixed model regression analyses.ResultsDecreasing trends were observed for sedentary behavior (for women), moderate PA, smoking, systolic blood pressure (SBP), diastolic blood pressure (DBP), high-density lipoprotein (HDL-c) and total cholesterol (TC), whereas increasing trends were observed for body mass index (BMI), triglycerides (TG), light PA, vigorous PA and sedentary behavior for men. Compared to the national trends, the trends in the 40-42-year-olds from Sogn & Fjordane were more beneficial in terms of TG, HDL-c and BMI but less beneficial in terms of SBP and DBP.ConclusionsOver a 35-year-period, this study indicates that the LTPA level has been relatively stable in the county of Sogn & Fjordane. Upward trends were observed in light and vigorous PA, whereas a downward trend was observed in moderate PA. For sedentary behavior, an upward trend was observed in men, whereas a downward trend was observed in women. For smoking, BP and cholesterol decreasing trends were found, but increasing trends were observed in BMI and TG. Compared with the national data, the trends in Sogn & Fjordane were more beneficial for TG, HDL-c and BMI but less beneficial for BP.

Aerobic fitness and metabolic health in children: A clinical validation of directly measured maximal oxygen consumption versus performance measures as markers of health

High aerobic fitness is consistently associated with a favorable metabolic health profile in children. However, measurement of oxygen uptake, regarded as the gold standard for evaluating aerobic fitness, is often not feasible. Thus, the aim of the present study was to perform a clinical validation of three measures of aerobic fitness (peak oxygen consumption [VO2peak] and time to exhaustion [TTE] determined from a graded treadmill protocol to exhaustion, and the Andersen intermittent running test) with clustered metabolic health in 10-year-old children. We included 93 children (55 boys and 38 girls) from Norway during 2012–2013 in the study. Associations between aerobic fitness and three different composite metabolic health scores (including lipoprotein subgroup particle concentrations, triglyceride, glucose, systolic blood pressure, and waist-to-height ratio) were determined by regression analyses adjusting for sex. The relationships among the measures of aerobic fitness were r = 0.78 for VO2peak vs. TTE, r = 0.63 for VO2peak vs. the Andersen test, and r = 0.67 for TTE vs. the Andersen test. The Andersen test showed the strongest associations across all markers of metabolic health (r = − 0.45 to − 0.31, p < 0.002), followed by VO2peak (r = − 0.35 to − 0.12, p < 0.256), and TTE (r = − 0.28 to − 0.10, p < 0.334). Our findings indicate that indirect measures of aerobic fitness do not stand back as markers of metabolic health status in children, compared to VO2peak. This is of great importance as good field tests provide opportunities for measuring aerobic fitness in many settings where measuring VO2peak are impossible.

The Andersen aerobic fitness test: New peak oxygen consumption prediction equations in 10 and 16-year olds

Measurement of aerobic fitness by determining peak oxygen consumption (VO2peak) is often not feasible in children and adolescents, thus field tests such as the Andersen test are required in many settings, for example in most school‐based studies. This study provides cross‐validated prediction equations for VO2peak based on the Andersen test in 10 and 16‐year‐old children. We included 235 children (n = 113 10‐year olds and 122 16‐year olds) who performed the Andersen test and a progressive treadmill test to exhaustion to determine VO2peak. Joint and sex‐specific prediction equations were derived and tested in 20 random samples. Performance in terms of systematic (bias) and random error (limits of agreement) was evaluated by means of Bland‐Altman plots. Bias varied from −4.28 to 5.25 mL/kg/min across testing datasets, sex, and the 2 age groups. Sex‐specific equations (mean bias −0.42 to 0.16 mL/kg/min) performed somewhat better than joint equations (−1.07 to 0.84 mL/kg/min). Limits of agreement were substantial across all datasets, sex, and both age groups, but were slightly lower in 16‐year olds (5.84‐13.29 mL/kg/min) compared to 10‐year olds (9.60‐15.15 mL/kg/min). We suggest the presented equations can be used to predict VO2peak from the Andersen test performance in children and adolescents on a group level. Although the Andersen test appears to be a good measure of aerobic fitness, researchers should interpret cross‐sectional individual‐level predictions of VO2peak with caution due to large random measurement errors.

Validity of noninvasive composite scores to assess cardiovascular risk in 10‐year‐old children

Agreement between and classification accuracy of six different noninvasive composite scores and a cardiovascular disease (CVD) risk factor score were investigated in 911 (466 boys and 445 girls) 10‐year‐old Norwegian children. A CVD risk factor score (triglyceride, total cholesterol/HDL ratio, homeostasis model assessment of insulin resistance, systolic blood pressure (SBP), waist‐to‐height ratio (WHtR), and cardiorespiratory fitness) and six noninvasive risk scores (fitness+three different measurements of fatness (body mass index (BMI), WHtR, and skinfolds), with and without inclusion of SBP) were calculated (mean z‐score by gender). Agreement was assessed using Bland‐Altman plots. The ability of noninvasive scores to correctly classify children with clustered CVD risk was examined by receiver operating characteristic (ROC) analysis and Cohens kappa coefficient (κ). For both sexes, the noninvasive scores without SBP showed excellent AUC values (AUC=0.93‐0.94, 95% CI=0.88‐0.98) and moderate kappa values (κ=0.49‐0.64) and had limits of agreement of 0.0±0.78‐0.89 (arbitrary unit). Inclusion of SBP increased AUC values (AUC=0.96‐0.97, 95% CI=0.94‐0.99), kappa values (κ=0.58‐0.69), and reduced limits of agreement (0.0±0.68‐0.76). Noninvasive scores that include fitness and fatness provide acceptable agreement and classification accuracy, allowing for widespread early identification of children that might be at risk for developing CVD later in life. SBP should be included in the noninvasive score to improve classification accuracy if possible.

Effects of the Active Smarter Kids (ASK) Physical Activity School-based Intervention on Executive Functions: A Cluster-Randomized Controlled Trial

ABSTRACT The purpose of this study was to examine the effects of a seven-month curriculum prescribed physical activity (PA) intervention (the Active Smarter Kids [ASK] intervention) on executive functions in 10-year-old Norwegian children. A linear mixed model was used to analyze data from 971–1,123 fifth grade children at 28 intervention schools and 29 control schools. The intervention constituted three PA elements: PA educational lessons, PA breaks, and PA homework, adding 165 minutes of PA to the mandatory 135 minutes of PA and physical education. There was no effect of the intervention on executive functions in the intention-to-treat analyses. Per protocol analyses (n = 776–850) revealed small effects of the intervention on the composite score of executive functions, cognitive flexibility, and motor skills. Cognitively engaging and coordinative demanding activities/games seem viable options to increase executive functions and possibly improve academic performance in children.