title: Prospective associations between physical activity and obesity among adolescent girls: racial differences and implications for prevention. Strength Training and Physical Activity in Boys: a Randomized Trial Serum lipids, glucose and insulin levels in healthy schoolchildren aged 9 and 15 years from central Sweden: Reference values in relation to biological, social and lifestyle factors Effect of fitness and physical activity on bone mass in adolescents: the HELENA Study Utilization of the PICO framework to improve searching PubMed for clinical questions Relations of moderate and vigorous physical activity to fitness and fatness in adolescents. Cross-sectional and longitudinal associations between physical activity and blood pressure in adolescence: birth cohort study. Relationships among fitness, body composition, and physical activity. Depressive symptoms and physical activity in adolescent girls. The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials Predicting students' physical activity and health-related well-being: a prospective cross-domain investigation of motivation across school physical education and exercise settings. A cluster randomized controlled trial of an incentive-based outdoor physical activity program. Canadian children's and youth's pedometer-determined steps/day, parent-reported TV watching time, and overweight/obesity: The CANPLAY Surveillance Study Bidirectional cross-sectional and prospective associations between physical activity and body composition in adolescence: Birth cohort study Physical activity and depression in adolescents: cross-sectional findings from the ALSPAC cohort Long-Term Effect of a School-Based Physical Activity Program (KISS) on Fitness and Adiposity in Children: A Cluster-Randomized Controlled Trial Prospective associations between objective measures of physical activity and fat mass in 12-14 year old children: the Avon Longitudinal Study of Parents and Children (ALSPAC) Effects of Changes in Adiposity and Physical Activity on Preadolescent Insulin Resistance: The Australian LOOK Longitudinal Study Effect of school based physical activity programme (KISS) on fitness and adiposity in primary schoolchildren: cluster randomised controlled trial Physical activity, sedentary behavior, and adiposity in English children. Physical activity and femoral neck bone strength during childhood: the Iowa Bone Development Study. Objectively measured physical activity correlates with indices of insulin resistance in Danish children. The European Youth Heart Study (EYHS). A Ballroom Dance Classroom Program Promotes Moderate to Vigorous Physical Activity in Elementary School Children Sustained effects of physical activity on bone health: Iowa Bone Development Study. A comprehensive physical activity promotion programme at elementary school: the effects on physical activity, physical fitness and psychosocial correlates of physical activity. Associations of body size and composition with physical activity in adolescent girls. A longitudinal study of sedentary behavior and overweight in adolescent girls. Effects of a 15-week accumulated brisk walking programme on the body composition of primary school children Effect of physical training and its cessation on percent fat and bone density of children with obesity. Comparison of accelerometer cut points for predicting activity intensity in youth. Thin adolescents: Who are they? What do they do? Socio-demographic and use-of-time characteristics. Improving the fitness and physical activity levels of primary school children: results of the Fit-4-Fun group randomized controlled trial. Objectively measured daily physical activity related to aerobic fitness in young children
abstract: OBJECTIVE To test for differences in prospect i ve associations between physical activity and obesity among black and white adolescent girls . DESIGN Prospect i ve cohort study using data from the National Heart , Lung , and Blood Institute Growth and Health Study . SETTING Multicenter study at the University of California ( Berkeley ) , Children 's Medical Center at the University of Cincinnati ( Cincinnati , Ohio ) , and Westat , Inc , and Group Health Association ( Rockville , Maryl and ) . PARTICIPANTS A total of 1148 adolescent girls ( 538 black and 610 white ) who provided valid data on levels of physical activity and obesity at ages 12 and 14 years . INTERVENTION Physical activity , assessed as accelerometer counts per day . MAIN OUTCOME MEASURES Three measurements of obesity were obtained using the Centers for Disease Control and Prevention definition of obesity ( at or above the age-specific 95th percentile of body mass index ) , the International Obesity Task Force reference body mass index cut points for obesity in children , and the sums of skinfold thickness ( with the cohort ≥90th percentile as indicative of obesity ) . RESULTS We found a strong negative dose-response association between quartiles of accelerometer counts per day at age 12 years and obesity at age 14 years ( using all 3 measurements of obesity ) in white but not black girls ( P < .001 for body mass index interaction and P = .06 for sums of skinfold thickness interaction ) . The odds ratios for obesity ( using the cohort ≥90th percentile for sums of skinfold thickness ) in adjusted models between the top and the bottom quartiles of accelerometer counts per day were 0.15 ( 95 % CI , 0.04 - 0.63 ; P = .03 for trend ) in white girls and 0.85 ( 95 % CI , 0.32 - 2.26 ; P = .93 for trend ) in black girls . CONCLUSIONS Higher levels of physical activity are prospect ively associated with lower levels of obesity in white adolescent girls but not in black adolescent girls . Obesity prevention interventions may need to be adapted to account for the finding that black girls are less sensitive to the effects of physical activity BACKGROUND : In developed societies levels of daily physical activity ( PA ) among school-age children are decreasing . This implies risk factors for cardiovascular and metabolic diseases . Specific strategies to improve levels of PA are needed . In prepubertal boys there is evidence that strength training increases spontaneous PA outside of training . METHODS : A total of 102 schoolchildren ( age 10–14 years ) in Switzerl and were r and omly assigned to  physical education classes or to participate twice weekly at a guided strength training program for 19 weeks  . Spontaneous PA energy expenditure ( PAEE ; 3axial accelerometry for 7 days ) , leg and arm strength , and body composition ( dual energy radiograph absorptiometry ) were measured at baseline , after 19 weeks of training intervention , and after 3 months of washout . RESULTS : There were no significant differences between the groups at baseline . In the intervention group , PAEE increased by 10 % from baseline to end of training in boys ( P = .02 ) , but not in girls . Leg and arm strength were increased owing to training intervention in both boys and girls . All other variables were unchanged . Baseline PAEE was significantly negatively correlated with changes of PAEE . CONCLUSIONS : Targeted strength training significantly increases daily spontaneous PA behavior in boys . The less active children showed the greatest increase in spontaneous PAEE . Girls showed a similar increase in strength , but not in spontaneous PAEE . This may be explained by their earlier pubertal development . Strength training may be a promising strategy in schools to counteract decreasing levels of PA Background . There is a shortage of reference values for cardiovascular risk factors such as serum lipids , glucose and insulin related to biological , social and lifestyle factors for Swedish children and adolescents . Such values are needed for planning and evaluation of public health activities , and for clinical use . Design and Methods . Data for this cross‐sectional , school‐based study were collected during a school year ( September to May ) . A r and om sample of 1137 girls and boys aged 9 and 15 years from two locations in central Sweden participated in the study , and blood sample s were taken from 969 of them . Methods . Fasting serum blood sample s were analysed for triglycerides , total cholesterol , high‐density lipoprotein cholesterol , glucose and insulin . Physical examination included measurement of height , weight and pubertal status . Question naires provided family background data . Total physical activity was measured by accelerometer registration . Results . Serum levels differed significantly between age and gender groups and were correlated to pubertal status . Neither genetic nor socio‐economic background nor smoking status influenced the serum levels . Insulin levels were elevated in subjects with a body mass index in the highest decentile , compared with the levels in the rest of the subjects . The insulin levels were inversely associated with total physical activity , and physical activity varied with season . Conclusions . Pubertal status ( biological age ) should to be considered in the interpretation of serum values in schoolchildren rather than chronological age . The interpretation of insulin values should include both body mass index and physical activity level , and perhaps also season . Previously described regional differences in serum lipid levels in Swedish adults seem to be present also in children Our aim is to analyse the effect on bone mass of : ( 1 ) physical fitness performance on a specific group of physical activity ( PA ) and , ( 2 ) PA on a specific physical fitness performance group . Bone mineral content ( BMC ) by dual energy X-ray absorptiometry ( DXA ) and PA by accelerometers was assessed in 373 Spanish adolescents ( 182 males ) . Adolescents were classified as : active and non-active ( ≥60 or < 60 min day−1 of moderate-vigorous PA ) . Fitness was assessed through speed/agility , strength and cardiorespiratory tests . Adolescents were classified by tertiles ( T1 , T2 and T3 ) . ANCOVA was used for the analysis with sex , height , lean mass , calcium intake and pubertal status as covariates . Adolescents with lower strength , speed/agility and cardiorespiratory fitness ( CRF ) showed lower BMC in the whole body and extremities compared with adolescents with better results in these tests , mainly those non-active adolescents . Non-active adolescents with high fitness levels showed higher BMC ( whole body and upper limbs ) than active ones . The conclusions included : ( 1 ) within the non-active group , lower levels of fitness were associated with lower BMC ; this might be through PA or trough an effect of PA on muscle mass . ( 2 ) Non-active adolescents with high level of fitness in most fitness tests showed higher BMC than their active peers , in spite of their lower PA levels . These unexpected results could be influenced by several factors such as genetics , nutrition , type of exercise or sport , hormones and skeletal age Background Supporting 21st century health care and the practice of evidence -based medicine ( EBM ) requires ubiquitous access to clinical information and to knowledge-based re sources to answer clinical questions . Many questions go unanswered , however , due to lack of skills in formulating questions , crafting effective search strategies , and accessing data bases to identify best levels of evidence . Methods This r and omized trial was design ed as a pilot study to measure the relevancy of search results using three different interfaces for the PubMed search system . Two of the search interfaces utilized a specific framework called PICO , which was design ed to focus clinical questions and to prompt for publication type or type of question asked . The third interface was the st and ard PubMed interface readily available on the Web . Study subjects were recruited from interns and residents on an inpatient general medicine rotation at an academic medical center in the US . Thirty-one subjects were r and omized to one of the three interfaces , given 3 clinical questions , and asked to search PubMed for a set of relevant articles that would provide an answer for each question . The success of the search results was determined by a precision score , which compared the number of relevant or gold st and ard articles retrieved in a result set to the total number of articles retrieved in that set . Results Participants using the PICO templates ( Protocol A or Protocol B ) had higher precision scores for each question than the participants who used Protocol C , the st and ard PubMed Web interface . ( Question 1 : A = 35 % , B = 28 % , C = 20 % ; Question 2 : A = 5 % , B = 6 % , C = 4 % ; Question 3 : A = 1 % , B = 0 % , C = 0 % ) 95 % confidence intervals were calculated for the precision for each question using a lower boundary of zero . However , the 95 % confidence limits were overlapping , suggesting no statistical difference between the groups . Conclusion Due to the small number of search es for each arm , this pilot study could not demonstrate a statistically significant difference between the search protocol s. However there was a trend towards higher precision that needs to be investigated in a larger study to determine if PICO can improve the relevancy of search results BACKGROUND It is unclear how moderate and vigorous intensities of physical activity ( PA ) are associated with cardiovascular fitness ( CVF ) and percentage of body fat ( % BF ) in adolescents . OBJECTIVE We tested the hypothesis that vigorous PA , to a greater degree than moderate PA , would be associated with better CVF and lower % BF . DESIGN This was a cross-sectional study of 421 black and white high school students ( x age : 16 y ) .  PA was measured with 5 d of accelerometry and expressed in min/d of moderate or vigorous PA .  CVF was measured with a multistage treadmill test and was expressed as the oxygen consumption at a heart rate of 170 bpm . % BF was measured with dual-energy X-ray absorptiometry . Multiple regressions were used to determine the degree to which variance in CVF and % BF was explained by PA , after control for age , sex , race , and the sex x race interaction . RESULTS A higher index for CVF was associated with higher amounts of moderate and vigorous PA ;  more variance was explained by vigorous than by moderate PA .  Lower % BF was associated with higher amounts of vigorous PA but not with the amount of moderate PA . CONCLUSION Black and white adolescents who engaged in relatively large amounts of free-living vigorous exercise were likely to be relatively fit and lean OBJECTIVES To explore cross-sectional and longitudinal associations between self-reported and accelerometry-based physical activity ( PA ) and blood pressure ( BP ) between 11 and 14 years of age . METHODS Prospect i ve birth cohort study in Pelotas , Brazil . Participants were 427 cohort members who were followed up with at 11 , 12 , and 14 years of age , and had question naire data on PA and BP at 11 and 14 years , as well as accelerometry and question naire data on PA at 12 years . Outcome measures were continuous systolic and diastolic BP at 14 years , and change in BP from 11 to 14 years . RESULTS PA was unrelated to systolic BP in any analyses . PA measured by accelerometry at 12 years , but not question naire-derived PA , was inversely associated with diastolic BP at 14 years of age in fully adjusted models . Those who exceeded the 300-minutes PA threshold at all 3 visits had a 2.6 mmHg lower mean increase in DBP from 11 to 14 years compared with those classified below the threshold in all visits . CONCLUSIONS Accelerometry-based PA was longitudinally inversely associated with  diastolic BP . This finding was not evident when analyzing self-reported PA at a given age , suggesting a possible underestimation of the association when using subjective data PURPOSE This study was design ed to examine the associations of physical activity and body composition with cardiorespiratory fitness in eighth grade girls . METHODS A r and om sample of 1440 eighth grade girls at 36 schools participated in this cross-sectional investigation , which represented an ethnically and geographically diverse group .  Cardiorespiratory fitness was assessed using a modified physical work capacity test on a cycle ergometer that predicted workload at a heart rate of 170 beats.min . Physical activity was assessed over 6 d in each girl using an accelerometer and body composition was estimated from body mass index and triceps skinfolds using a previously vali date d equation . Pearson correlations and multiple regression analyses were used to determine the relationships among fitness , physical activity , and body composition . RESULTS Significant linear relationships among cardiorespiratory fitness , body composition , and physical activity were found . The combination of fat and fat-free mass along with racial group and a race by fat-free-mass interaction accounted for 18 % ( R ) of the variation in physical fitness . Adding moderate-to-vigorous physical activity to the regression model increased the R to 22 % . Black girls had somewhat lower fitness levels ( P < 0.05 ) especially at higher levels of fat and fat-free mass than other racial/ethnic groups . CONCLUSIONS Physical activity , fat-free mass , and the interaction between fat-free mass and racial group are significantly associated with cardiorespiratory fitness in adolescent girls PURPOSE To evaluate the relationship between depressive symptoms and physical activity in a geographically and ethnically diverse sample of sixth- grade adolescent girls . METHODS The Trial of Activity for Adolescent Girls ( TAAG ) baseline measurement included a r and om sample ( N = 1721 ) of sixth- grade girls in 36 schools at six field sites . Measurements were  accelerometry  and the 3-d Physical Activity Recall ( 3DPAR ) for  physical activity  , and the Center for Epidemiological Studies -Depression scale ( CES-D ) for depressive symptoms . RESULTS Girls with complete data ( N = 1397 ) , mean age 12 yr , had an average  CES-D score of 14.7 ( SD = 9.25 ) and engaged in an average of about 460 min of sedentary activity , < 24 min of moderate to vigorous physical activity ( MVPA ) , and < 6 min of vigorous physical activity ( VPA ) in an 18-h day . Thirty-minute segments of MVPA ranged in number from 3.9 to 1.2 , and METS for these segments ranged from > 3.0 to > 6.5 . Mixed-model regression indicated no relationship between depressive symptoms and physical activity ; however , a significant but modest inverse relationship between sedentary activity and depressive symptoms was observed . CONCLUSION A sufficient sample size , st and ardized procedures , and vali date d instruments characterized this study ; however , a relationship between depressive symptoms and physical activity was not observed for sixth- grade girls from diverse geographic locations . The average CES-D score was lower than is considered clinical ly meaningful for either adolescents or adults , and MET-minutes of sedentary activity were high . This combination of data may be different from other studies and could have contributed to the unexpected finding . This unexpected finding is informative , however , because it shows the need for additional research that includes a wider range of possible combinations of data , especially with young adolescent girls Flaws in the design , conduct , analysis , and reporting of r and omised trials can cause the effect of an intervention to be underestimated or overestimated . The Cochrane Collaboration ’s tool for assessing risk of bias aims to make the process clearer and more A three-wave prospect i ve design was used to assess a model of motivation guided by self-determination theory ( Ryan & Deci , 2008 ) spanning the context s of  school physical education ( PE ) and exercise .  The outcome variables examined were health-related quality of life ( HRQoL ) , physical self-concept ( PSC ) , and 4 days of objective ly assessed estimates of activity . Secondary school students ( n = 494 ) completed question naires at three separate time points and were familiarized with how to use a sealed pedometer . Results of structural equation modeling supported a model in which perceptions of autonomy support from a PE teacher positively predicted PE-related need satisfaction ( autonomy , competence , and relatedness ) . Competence predicted PSC , whereas relatedness predicted HRQoL. Autonomy and competence positively predicted autonomous motivation toward PE , which in turn positively predicted autonomous motivation toward exercise ( i.e. , 4-day pedometer step count ) . Autonomous motivation toward exercise positively predicted step count , HRQoL , and PSC . Results of multi sample structural equation modeling supported gender invariance . Suggestions for future work are discussed OBJECTIVE To evaluate an incentive-based physical activity intervention to increase physical activity and fitness among children in a 9-month cluster r and omized controlled trial . STUDY DESIGN Children aged 6 - 12 years were r and omized to control ( n = 138 from 106 families ) or intervention arm ( n = 147 from 106 families ) . The intervention included incentives for meeting step targets as measured by pedometers and structured weekend outdoor activities . Outcomes included trends in activity for the intervention group and between-group differences in pedometer steps , 6-minute walk test , body mass index , and parent-reported Pediatric Quality of Life Inventory . RESULTS At follow-up , children in the intervention group recorded significantly more pedometer steps than controls over the entire week ( 8660 vs 7767 ; P = .010 ) , on weekdays ( 8646 vs 7826 ; P = .041 ) , and on weekends ( 8779 vs 7684 ; P = .018 ) . Three different trajectory classes were identified . The first group increased activity but was not sustained , the second group met the target step levels , and the third group significantly surpassed the step goals . The intervention group showed trends toward longer 6-minute walk test times and higher Pediatric Quality of Life Inventory scores , but the differences were not statistically significant . CONCLUSION Incentives for increased step activity were effective in producing greater steps and showed a ( nonsignificant ) trend toward improvements in other health outcomes . Thus , future incentive trials should be incorporate greater step targets and longer follow-up periods to provide evidence of the long-term effect of these incentives on children 's health Background This study examines associations between pedometer-determined steps/day and parent-reported child 's Body Mass Index ( BMI )  and time typically spent watching television between school and dinner . Methods Young people ( aged 5 - 19 years ) were recruited through their parents by r and om digit dialling and mailed a data collection package . Information on height and weight and time spent watching television between school and dinner on a typical school day was collected from parents . In total , 5949 boys and 5709 girls reported daily steps .  BMI was categorized as overweight or obese using Cole 's cut points . Participants wore pedometers for 7 days and logged daily steps . The odds of being overweight and obese by steps/day and parent-reported time spent television watching were estimated using logistic regression for complex sample s. Results Girls had a lower median steps/day ( 10682 versus 11059 for boys ) and also a narrower variation in steps/day ( interquartile range , 4410 versus 5309 for boys ) . 11 % of children aged 5 - 19 years were classified as obese ; 17 % of boys and girls were overweight . Both boys and girls watched , on average , < 40 minutes of television between school and dinner on school days . Adjusting for child 's age and sex and parental education , the odds of a child being obese decreased by 20 % for every extra 3000 steps/day and increased by 21 % for every 30 minutes of television watching . There was no association of being overweight with steps/day , however the odds of being overweight increased by 8 % for every 30 minutes of additional time spent watching television between school and dinner on a typical school day . Discussion Television viewing is the more prominent factor in terms of predicting overweight , and it contributes to obesity , but steps/day attenuates the association between television viewing and obesity , and therefore can be considered protective against obesity . In addition to replacing opportunities for active alternative behaviours , exposure to television might also impact body weight by promoting excess energy intake . Conclusions In this large nationally representative sample , pedometer-determined steps/day was associated with reduced odds of being obese ( but not overweight ) whereas each parent-reported hour spent watching television between school and dinner increased the odds of both overweight and obesity Abstract The aim of this study was to investigate the cross-sectional and prospect i ve associations between physical activity and  body composition in adolescence . This is a prospect i ve study , including 4,103 adolescents belonging to the Pelotas ( Brazil ) 1993 birth cohort , who were followed up at the mean ages of 11.3 and 14.7 years . Sub sample analyses included 511 individuals with accelerometry and deuterium dilution data at 13.3 years .  Sum of skinfolds at age 11.3 years was highly correlated with skinfolds at age 14.7 years ( rho = 0.74 , P < 0.001 ) . More than 85 % of participants remained in the same quintile or changed by not more than one quintile during the 3.4 year period .  Tracking of physical activity  was considerably lower , although still significant ; the correlation was 0.24 ( P < 0.001 ) and 61.4 % of the adolescents moved one or less quintiles . In fully-adjusted models , no significant cross-sectional or longitudinal associations were found between physical activity and body composition , neither in boys nor in girls . These null results were confirmed in the 511 individuals with accelerometry and deuterium data . We provide evidence of  tracking of physical activity and particularly body composition during adolescence . Our results do not support the hypothesis that physical activity and fatness are strongly related in adolescents Purpose Few studies have examined the association between physical activity ( PA ) , measured objective ly , and  adolescent depressive symptoms .  The aim of this study was to determine whether there is an association between objective measures of PA ( total PA and time spent in moderate and vigorous PA ( MVPA ) ) and adolescent depressive symptoms . Methods Data on 2,951 adolescents participating in ALSPAC were used .  Depressive symptoms were measured using the self-report Mood and Feelings Question naire ( MFQ )  ( short version ) . Measures of  PA  were based on accelerometry . The association between PA and MFQ scores was modelled using ordinal regression . Results Adolescents who were more physically active ( total PA or minutes of MVPA ) had a reduced odds of depressive symptoms [ ORadj  total PA  ( tertiles ) : medium 0.82 ( 95 % CI : 0.69 , 0.97 ) ; high 0.69 ( 95 % CI : 0.57 , 0.83 ) ] ; ORadj per 15 min MVPA  : 0.92 ( 95 % CI : 0.86 , 0.98 ) . In a multivariable model including both  total PA  and the percentage of time spent in MVPA , total PA  was associated with depressive symptoms ( ORadj  total PA  ( tertiles ) : medium 0.82 ( 95 % CI : 0.70 , 0.98 ) ; high 0.70 ( 95 % CI : 0.58 , 0.85 ) but the percentage of time spent in  MVPA  was not independently associated with depressive symptoms [ ORadj MVPA ( tertiles ) medium 1.05 ( 95 % CI : 0.88 , 1.24 ) , high 0.91 ( 95 % CI : 0.77 , 1.09 ) ] . Conclusions The total amount of PA undertaken was associated with  adolescent depressive symptoms , but the amount of time spent in MVPA , once total PA was accounted for , was not . If confirmed in longitudinal studies and r and omised controlled trials , this would have important implication s for public health messages Background School-based intervention studies promoting a healthy lifestyle have shown favorable immediate health effects . However , there is a striking paucity on long-term follow-ups . The aim of this study was therefore to assess the 3 yr-follow-up of a cluster-r and omized controlled school-based physical activity program over nine month with beneficial immediate effects on body fat , aerobic fitness and physical activity . Methods and Findings Initially , 28 classes from 15 elementary schools in Switzerl and were grouped into an intervention ( 16 classes from 9 schools , n = 297 children ) and a control arm ( 12 classes from 6 schools , n = 205 children ) after stratification for grade ( 1st and 5th grade rs ) . Three years after the end of the multi-component physical activity program of nine months including daily physical education ( i.e. two additional lessons per week on top of three regular lessons ) , short physical activity breaks during academic lessons , and daily physical activity homework , 289 ( 58 % ) participated in the follow-up . Primary outcome measures included body fat ( sum of four skinfolds ) , aerobic fitness ( shuttle run test ) , physical activity ( accelerometry ) , and quality of life ( question naires ) . After adjustment for grade , gender , baseline value and clustering within classes , children in the intervention arm compared with controls had a significantly higher average level of aerobic fitness at follow-up ( 0.373 z-score units [ 95%-CI : 0.157 to 0.59 , p = 0.001 ] corresponding to a shift from the 50th to the 65th percentile between baseline and follow-up ) , while the immediate beneficial effects on the other primary outcomes were not sustained . Conclusions Apart from aerobic fitness , beneficial effects seen after one year were not maintained when the intervention was stopped . A continuous intervention seems necessary to maintain overall beneficial health effects as reached at the end of the intervention . Trial Registration ControlledTrials.com IS RCT Objective To investigate associations between physical activity at age 12 and subsequent adiposity at age 14 . Design Prospect i ve birth cohort study with data collected between 2003 and 2007 . Setting Original recruitment in 1991 - 2 of 14 541 pregnant women living in the former County of Avon ( United Kingdom ) . Participants At age 12 , 11 952 children were invited to attend the research clinic . Of these , 7159 attended , and 4150 ( 1964 boys , 2186 girls ) provided sufficient data on exposure , outcome , and confounding variables . Main outcome measure Fat mass at age 14 , measured by dual emission x ray absorptiometry , associated with physical activity at age 12 , measured by accelerometry . Results Prospect i ve associations of fat mass at age 14 ( outcome ) with physical activity at age 12 ( exposure ) were strong for both  total activity ( accelerometer counts/min ) and for daily amount of moderate-vigorous physical activity  ( min/day ) . An extra 15 minutes of moderate-vigorous physical activity per day at age 12 was associated with lower fat mass at age 14 in boys ( by 11.9 % ( 95 % confidence interval 9.5 % to 14.3 % ) ) and girls ( by 9.8 % ( 6.7 % to 12.8 % ) ) . The proportion of physical activity due to moderate-vigorous physical activity was between 20 % and 30 % in boys and girls at the two ages . Conclusions Higher levels of physical activity , in particular activity of moderate to higher intensities , are prospect ively associated with lower levels of fat mass in early adolescence . Interventions to raise levels of physical activity in children are likely to be important in the fight against obesity Background In a previous longitudinal analysis of our cohort as 8 to 10 year-olds , insulin resistance ( IR ) increased with age , but was not modified by changes in percent body fat ( % BF ) , and was only responsive to changes in physical activity ( PA ) in boys . We aim ed to determine whether these responses persisted as the children approached adolescence . Methods In this prospect i ve cohort study , 256 boys and 278 girls were assessed at ages 8 , 10 and 12 years for fasting blood glucose and insulin , % BF ( dual energy X-ray absorptiometry ) ; PA ( 7-day pedometers ) , fitness ( multistage run ) ; and pubertal development ( Tanner stage ) . Results From age 8 to 12 years , the median homeostatic model of IR ( HOMA-IR ) doubled in boys and increased 250 % in girls . By age 12 , 23 % of boys and 31 % of girls had elevated IR , as indicated by HOMA-IR greater than 3 . Longitudinal relationships , with important adjustments for covariates body weight , PA , % BF , Tanner score and socioeconomic status showed that , on average , for every 1 unit reduction of % BF , HOMA-IR was lowered by 2.2 % ( 95 % CI 0.04–4 ) in girls and 1.6 % ( 95 % CI 0–3.2 ) in boys . Furthermore , in boys but not girls , HOMA-IR was decreased by 3.5 % ( 95%CI 0.5–6.5 ) if PA was increased by 2100 steps/day . Conclusion Evidence that a quarter of our apparently healthy 12 year-old Australians possessed elevated IR suggests that community-based education and prevention strategies may be warranted . Responsiveness of IR to changes in % BF in both sexes during late preadolescence and to changes in PA in the boys provides a specific basis for targeting elevated IR . That body weight was a strong covariate of IR , independent of % BF , points to the importance of adjusting for weight in correctly assessing these relationships in growing children Objective To assess the effectiveness of a school based physical activity programme during one school year on physical and psychological health in young schoolchildren . Design Cluster r and omised controlled trial . Setting 28 classes from 15 elementary schools in Switzerl and r and omly selected and assigned in a 4:3 ratio to an intervention ( n=16 ) or control arm ( n=12 ) after stratification for grade ( first and fifth grade ) , from August 2005 to June 2006 . Participants 540 children , of whom 502 consented and presented at baseline . Intervention Children in the intervention arm ( n=297 ) received a multi-component physical activity programme that included structuring the three existing physical education lessons each week and adding two additional lessons a week , daily short activity breaks , and physical activity homework . Children ( n=205 ) and parents in the control group were not informed of an intervention group . For most outcome measures , the assessors were blinded . Main outcome measures Primary outcome measures included body fat ( sum of four skinfolds ) , aerobic fitness ( shuttle run test ) , physical activity ( accelerometry ) , and quality of life ( question naires ) . Secondary outcome measures included body mass index and cardiovascular risk score ( average z score of waist circumference , mean blood pressure , blood glucose , inverted high density lipoprotein cholesterol , and triglycerides ) . Results 498 children completed the baseline and follow-up assessment s ( mean age 6.9 ( SD 0.3 ) years for first grade , 11.1 ( 0.5 ) years for fifth grade ) . After adjustment for grade , sex , baseline values , and clustering within classes , children in the intervention arm compared with controls showed more negative changes in the z score of the sum of four skinfolds ( −0.12 , 95 % confidence interval −0.21 to −0.03 ; P=0.009 ) . Likewise , their z scores for aerobic fitness increased more favourably ( 0.17 , 0.01 to 0.32 ; P=0.04 ) , as did those for moderate-vigorous physical activity in school ( 1.19 , 0.78 to 1.60 ; P<0.001 ) , all day moderate-vigorous physical activity ( 0.44 , 0.05 to 0.82 ; P=0.03 ) , and total physical activity in school ( 0.92 , 0.35 to 1.50 ; P=0.003 ) . Z scores for overall daily physical activity ( 0.21 , −0.21 to 0.63 ) and physical quality of life ( 0.42 , −1.23 to 2.06 ) as well as psychological quality of life ( 0.59 , −0.85 to 2.03 ) did not change significantly . Conclusions A school based multi-component physical activity intervention including compulsory elements improved physical activity and fitness and reduced adiposity in children . Trial registration Current Controlled Trials IS RCT N15360785 BACKGROUND The importance of variation in total volume of physical activity or moderate- to vigorous-intensity physical activity ( MVPA ) to development of body fatness in childhood is unclear , and it is unclear if physical activity has a greater influence on adiposity in boys than girls . PURPOSE To assess relationships between 2-year changes in objective ly measured physical activity , sedentary behavior , and adiposity in English children . METHODS Prospect i ve cohort study , set in Northeast Engl and , of a socioeconomically representative sample of 403 children . Measures were change in accelerometer-determined physical activity and sedentary behavior  from age 7 to 9 years ( data collected 2006/2007 and 2008/2009 ; analyzed in 2010 ) and concurrent change in adiposity ( fat mass index derived from bioelectric impedance ) and change in BMI Z-score . RESULTS Decline in MVPA was associated with a greater increase in fat mass index in boys but not girls . Declining MVPA was associated with increased BMI Z-score in boys but not girls . Increased sedentary behavior was not associated with increased BMI Z-score in either gender . CONCLUSIONS Avoiding mid-late childhood reductions in MVPA may reduce excessive fat gain , although such strategies may have greater impact on boys than girls Structural adaptations of bone to changing mechanical loads have recently been documented during adolescence . However , little is known about how bone adapts structurally during the earlier years . Using a longitudinal observational design spanning 6 years of growth ( age range 4 to 12 years ) , we investigated associations between everyday physical activity and hip geometry in a cohort of healthy Midwestern children ( n=468 ) . Femoral neck ( FN ) cross sectional area ( CSA , cm(2 ) ) and FN section modulus ( Z , cm(3 ) ) were used to describe hip geometry . CSA and Z , indices of axial and bending strength , were assessed using dual-energy X-ray absorptiometry ( DXA ) scans and the hip structure analysis ( HSA ) program . Moderate and vigorous physical activity ( MVPA ) was assessed using accelerometry-based activity monitors and calculated as the number of minutes > or = 3000 accelerometry movement counts . Data were analyzed using multilevel ( r and om- and fixed-effects ) regression models with adjustment for age ( year ) , height ( cm ) , and weight ( kg ) or lean mass ( kg ) . For boys and girls , MVPA was a positive independent predictor of CSA and Z ( p<0.05 ) . On average , children who participated in 40 min of MVPA per day would be expected to have 3 % to 5 % greater CSA and Z than peers participating in 10 min of MVPA per day . Ten-minute increases in daily MVPA had similar effects on CSA in girls and Z in boys as did each additional 1 kg of body weight . When lean mass was substituted for weight , MVPA continued to be a positive independent predictor of CSA and Z for boys , but not girls . This study demonstrates that everyday amounts of physical activity in children are associated with indices of FN bone strength during childhood . Differences in lean mass mediate associations between physical activity and hip geometry in girls , but only somewhat in boys . These results suggest that physical activity is an important contributor to bone strength prior to adolescence and that increasing levels of physical activity during childhood are likely to enhance optimal bone strength OBJECTIVE To explore the association between measures of insulin resistance with objective ly assessed physical activity . DESIGN School-based , cross-sectional study . SUBJECTS A r and omly selected sample of 589 children ( 310 girls , 279 boys , mean ( st and ard deviations , s.d . ) age=9.7 ( 0.44 ) y , weight=33.6 ( 6.4 ) kg , height=1.39 ( 0.06 ) m ) from Denmark . METHODS Fasting blood sample s were analysed for serum insulin and glucose .  Physical activity  was measured with the uniaxial Computer Science and Applications ( CSA ) model 7164 accelerometer , worn for at least 3 days ( > /=10 h day(-1 ) ) .  Adiposity was assessed by the sum of four skinfolds . Multiple linear regression were performed to model insulin and glucose from average CSA output , adjusted for age , gender , puberty , ethnicity , birth weight , parental smoking , socioeconomic group , and CSA unit . In addition , we adjusted for skinfold thickness . RESULTS Mean fasting serum glucose ranged from 4.1 to 6.5 mmol l(-1 ) with a mean ( s.d . ) of 5.1 ( 0.37 ) mmol l(-1 ) . Fasting insulin was negatively correlated with CSA output on levels of adjustment . Fasting glucose was not significantly associated with physical activity . However , in girls both indices of insulin resistance were significantly related to activity , whereas in boys none of the associations were significant . CONCLUSION Physical activity is inversely associated with fasting insulin in the nondiabetic range of fasting glucose . The relationship was stronger for insulin than for glucose , indicating compensatory action by the beta cells . Our data emphasise the importance of  physical activity in children for the maintenance of metabolic control Purpose . To determine if an existing ballroom dance classroom program meets national recommendations to engage children in moderate to vigorous physical activity ( MVPA ) for ≥ 50 % of class time and to determine class effects on body mass index ( BMI ) . Design . Prospect i ve descriptive study . Setting . Two New York City public schools . Participants . Seventy-nine fourth and fifth grade students . Measurements . The System for Observing Fitness Instruction Time ( SOFIT ) and direct heart rate monitoring were used to determine participants ' MVPA levels during class time . Weight and height were measured to calculate BMI . Analysis . Means were calculated for continuous variables ; frequency counts and percentages were calculated for categorical variables . Change in BMI percentiles was assessed by using Bhapkar 's χ2 test of overall marginal homogeneity . Results . Data from SOFIT observations showed that a mean of 50.0 % and 67.0 % of class time in the first and second halves of the program , respectively , were spent in MVPA . Data from the heart rate monitoring revealed that 71.1 % of students were at ≥ 25 % heart rate reserve , which indicated MVPA for ≥ 50 % of class time . Improvement was seen in BMI percentile ( p = .051 ) . Conclusion . Ballroom dance provides MVPA in elementary school children for ≥ 50 % of class time and has a positive impact on BMI percentiles Studies of youth athletics and interventions have shown some maintenance of bone mineral content ( BMC ; g ) after cessation of training , but less is known about sustained effects of everyday physical activity ( PA ) . Using a prospect i ve cohort , this report examined potential effects of  childhood PA  on  adolescent BMC . Participants ( N=156 boys , 170 girls ) had exams at ages 5 , 13 , and 15 . Body size and maturity were determined using anthropometry . Moderate-to-vigorous-intensity PA ( MVPA ) and vigorous-intensity PA ( Vigorous PA ) were measured using accelerometry .  BMC of the spine and hip was measured using dual-energy X-ray absorptiometry . Mixed regression models tested whether PA at age 5 affected BMC at ages 13 and 15 after adjustment for age ( year ) , height ( cm ) , weight ( kg ) , maturity ( pre-peak height velocity or post ) , and activity level ( min/day ) . Analysis was repeated to control for age 5 BMC . On average , boys participated in 59 , 52 , and 38 min of MVPA and 13 , 17 , and 11 min of Vigorous PA at ages 5 , 13 , and 15 , respectively . MVPA ( β=0.799 ) and Vigorous PA ( β=1.338 ) at age 5 predicted later spine BMC ( p<0.05 ) . MVPA ( β=0.480 ) at age 5 predicted hip BMC . Girls participated in 47 , 33 , and 26 min of MVPA and 10 , 9 and 7 min of Vigorous PA at ages 5 , 13 , and 15 , respectively . Neither MVPA nor Vigorous PA  predicted later spine BMC . MVPA ( β=0.302 ) at age 5 predicted hip BMC . After controlling for BMC at age 5 as well as the other covariates , the effect of MVPA ( β=0.695 ) and Vigorous PA ( β=1.079 ) at age 5 remained significant for boys at the spine . For girls , neither MVPA nor Vigorous PA at age 5 predicted spine or hip BMC . Children 's early PA  appears to have a modest effect on  adolescent BMC at the critical regions of spine and hip ; benefits may be greater for geometric changes , which future studies should include OBJECTIVE To evaluate the effects of a comprehensive physical activity ( PA ) promotion programme in elementary schools on children 's total PA levels , leisure-time PA , physical fitness and psychosocial correlates of PA . DESIGN A pre-test-post-test design over two school years . SETTING AND SUBJECTS Sixteen elementary schools ( 764 children , mean age : 11.2 + /- 0.7 years ) were r and omly assigned to the intervention condition ( n = 8) and the control condition ( n = 8) . The intervention included a health-related physical education programme , an extracurricular PA promotion programme and classroom-based PA education lessons . In the total sample , leisure-time PA , psychosocial correlates of PA and physical fitness were measured using a PA question naire and the Eurofit test battery . In a sub- sample , total PA levels were measured using an accelerometer . RESULTS According to accelerometer data , children 's moderate PA and moderate-to-vigorous PA ( MVPA ) levels decreased less in the intervention schools than in the control schools ( P < 0.01 ) . The average time spent on MVPA decreased by 9 min per day in the intervention schools compared with 33 min per day in the control schools . Children in the intervention schools reported significantly more moderate PA in leisure time than the controls ( P < 0.05 ) . No overall improvement of physical fitness and no effects on the psychosocial correlates of PA were found . CONCLUSIONS The comprehensive PA promotion programme was successful in preventing a decline in children 's  total activity levels . Furthermore , the intervention increased children 's PA engagement in leisure time . Therefore , implementation needs to be encouraged PURPOSE To examine whether components of body composition ( size , fat mass , and fat-free mass ) were related to physical activity . METHODS A r and om sample of 60 eligible sixth grade girls at each of 36 schools ( six schools per region and six regions in total sample ) ; complete measurements on 1,553 girls .  Physical activity was assessed over 6 d in each girl using an accelerometer , and body composition was assessed using a multiple regression equation using body mass index and triceps skinfold . Minutes of moderate-to-vigorous and vigorous physical activity  were estimated from accelerometer counts per 30 s above threshold values determined from a previous study . RESULTS Significant inverse relationships were found for all measures of body size and composition and all physical activity indices . The combination of fat and fat-free mass expressed as a weight and as an index ( divided by height squared ) along with race , SES , site , and school were most highly associated with physical activity in multiple regression analysis , accounting for 14 - 15 % of the variance in physical activity . Fat mass was more closely related to moderate-to-vigorous physical activity ( MVPA ) and vigorous physical activity ( VPA ) than fat-free mass with higher st and ardized regression coefficients . CONCLUSION We conclude that both fat mass or fat mass index as well as fat-free mass or fat-free mass index make independent contributions in association with physical activity levels . These indices are recommended for future studies The aim of this study is to examine  sedentary and light activity  in relation to overweight in adolescent girls . Adolescent girls were r and omly recruited from 36 schools participating in the Trial of Activity for Adolescent Girls ( TAAG ) . Assessment s included age , ethnicity , socioeconomic status , and body composition estimated from weight , height , and triceps skinfold .  Sedentary and light activity  was measured for 6 days using accelerometry in 6th and in 8th grade among two r and omly sample d cross-sections of girls .  Sedentary activity  increased from the 6th to 8th grade by 51.5 min/day . In the 8th grade , a significantly higher number of hours in sedentary activity for each of the 6-days of measurement were evident with higher tertiles of percent body fat ( 30 - 35 % , > 35 % fat ) ( P < 0.05 ) , but not across all increasing tertiles of BMI ( 5th to 85th , 85th to 95th , and > 95th percentiles ) . The increase in sedentary activity was observed on weekdays , but not on weekends for percent body fat tertiles . In the cohort of girls measured in both 6th and 8th grade s , the mean cross-sectional coefficient estimates were significant for percent body fat , but not BMI for sedentary and light activities . Adolescent girls from the 6th to 8th grade are shifting their time from light to more  sedentary activity as measured by accelerometers . In addition , the increase in sedentary activity is not associated with an adverse effect on BMI or percent body fat . The eventual impact of this shift to a more sedentary lifestyle on body composition and other outcomes needs to be evaluated further Abstract The purpose of this study was to establish whether an accumulated brisk walking programme , performed during the school day , is effective in changing body composition in primary school children aged 5–11 years . Altogether , 152 participants ( 79 boys and 73 girls ) took part in this repeated- measures intervention study , divided into groups of walkers and controls . The walkers took part in the intervention during school time , which involved brisk walking around the school grounds for 15 min in the morning and afternoon , at least three times a week for 15 weeks . This represented an additional 90 min of moderate physical activity per week . The controls undertook their usual school day activities . Pre- and post-intervention anthropometric and body composition measures were taken . Body fat ( −1.95 ± 2.6 % ) and fat mass ( −0.49 ± 1.0 kg ) were significantly reduced in the walkers after the intervention , whereas the controls showed no significant changes in these measures . Our results show that regular accumulated bouts of brisk walking during the school day can positively affect body composition in primary school children OBJECTIVE We determined the effect of 4-month periods of physical training ( PT ) and detraining on percent fat ( percent fat ) and bone density of children with obesity . RESEARCH METHODS AND PROCEDURES Subjects were 79 7- to 11-year-old children with obesity ; 34 were white , 44 were black , and 1 was Asian , 26 were male and 53 were female . They were r and omly assigned to two groups : group 1 engaged in PT for the first 4 months , while group 2 engaged in PT during the second 4 months . Body composition was measured with dual energy absorptiometry , and diet was measured with 4 days of recall for each 4-month period . PT was offered 5 days/week for 40 minutes/session , heart rate monitors were worn , and no dietary information was given ; mean attendance was 80 % , and mean heart rate per session was 157 bpm . RESULTS Group by time interactions across the three time-points ( from analysis of variance ) were significant for percent fat ( p = < 0.001 ) and bone density ( p = 0.045 ) . Both groups declined in percent fat during the periods of PT , by an average of 1.6 % fat units ; in the 4 months after cessation of PT , group 1 increased by 1.3 % fat . In both groups , bone density increased more during periods of PT ( 0.025 g/cm2 ) than during periods of no PT ( 0.010 g/cm2 ) . No significant PT vs. no-PT differences were found for dietary intake of energy , macronutrients , or calcium . DISCUSSION This study suggests that regular exercise , without dietary intervention , can enhance the body composition of children with obesity UNLABELLED The absence of comparative validity studies has prevented research ers from reaching consensus regarding the application of intensity-related accelerometer cut points for children and adolescents . PURPOSE This study aim ed to evaluate the classification accuracy of five sets of independently developed ActiGraph cut points using energy expenditure , measured by indirect calorimetry , as a criterion reference st and ard . METHODS A total of 206 participants between the ages of 5 and 15 yr completed 12 st and ardized activity trials . Trials consisted of sedentary activities ( lying down , writing , computer game ) , lifestyle activities ( sweeping , laundry , throw and catch , aerobics , basketball ) , and ambulatory activities ( comfortable walk , brisk walk , brisk treadmill walk , running ) . During each trial , participants wore an ActiGraph GT1 M , and V˙O2 was measured breath-by-breath using the Oxycon Mobile portable metabolic system . Physical activity intensity was estimated using five independently developed cut points : Freedson/Trost ( FT ) , Puyau ( PU ) , Treuth ( TR ) , Mattocks ( MT ) , and Evenson ( EV ) . Classification accuracy was evaluated via weighted κ statistics and area under the receiver operating characteristic curve ( ROC-AUC ) . RESULTS Across all four intensity levels , the EV ( κ=0.68 ) and FT ( κ=0.66 ) cut points exhibited significantly better agreement than TR ( κ=0.62 ) , MT ( κ=0.54 ) , and PU ( κ=0.36 ) . The EV and FT cut points exhibited significantly better classification accuracy for moderate- to vigorous-intensity physical activity ( ROC-AUC=0.90 ) than TR , PU , or MT cut points ( ROC-AUC=0.77 - 0.85 ) . Only the EV cut points provided acceptable classification accuracy for all four levels of physical activity intensity and performed well among children of all ages . The widely applied sedentary cut point of 100 counts per minute exhibited excellent classification accuracy ( ROC-AUC=0.90 ) . CONCLUSIONS On the basis of these findings , we recommend that research ers use the EV ActiGraph cut points to estimate time spent in sedentary , light- , moderate- , and vigorous-intensity activity in children and adolescents OBJECTIVES Examine : ( 1 ) the anthropometric , socio-demographic and use-of-time characteristics of thin adolescents , and ( 2 ) compare these characteristics to other weight status categories . METHODS Data were from the 2007 National Children 's Nutrition and Physical Activity Survey which collected data on a r and om sample of 2200 9 to 16 year old Australians from February to August 2007 . Seven socio-demographic variables , anthropometric data ( height and weight were measured ) and nine use-of-time variables were used , and compared across the weight status categories .  Physical activity  was measured using pedometers and the Multimedia Activity Recall for Children and Adults . RESULTS 5.3 % of adolescents were classified as thin , a percentage which did not significantly vary by age , sex , indigenous status , household income , education level or family structure . Relative to other adolescents , thin adolescents were shorter and lighter . Thin adolescents were less active than their normal weight peers , but walked further and accumulated significantly less screen and TV time than obese adolescents . CONCLUSION Thin adolescents were found in similar proportions across all socio-demographic b and s. Thin adolescents recorded similar physical activity levels to their normal weight peers , but were more active than obese adolescents . The findings from the study support in part the theory of thinness related developmental delay OBJECTIVE To evaluate the impact of a multi-component school-based physical activity intervention ( Fit-4-Fun ) on health-related fitness and objective ly measured physical activity in primary school children . METHODS Four Hunter primary schools were recruited in April , 2011 and r and omized by school into treatment or control conditions . Participants included 213 children ( mean age = 10.72 years ± 0.6 ; 52.2 % female ) with the treatment group ( n = 118 ) completing the 8-week Fit-4-Fun Program . Participants were assessed at baseline and 6-month follow-up , with a 91 % retention rate . Cardio-respiratory fitness ( CRF ) ( 20 m shuttle run ) was the primary outcome , and secondary outcomes included body composition ( BMI , BMI ( Z ) ) , muscular fitness ( 7-stage sit-up test , push-up test , basketball throw test , St and ing Jump ) , flexibility ( sit and reach ) and physical activity ( 7 days pedometry ) . RESULTS After 6-months , significant treatment effects were found for CRF ( adjusted mean difference , 1.14 levels , p < 0.001 ) , body composition ( BMI mean , -0.96 kg/m(2 ) , p < 0.001 and BMI z-score mean -0.47 z-scores , p < 0.001 ) , flexibility ( sit and reach mean , 1.52 cm , p = 0.0013 ) , muscular fitness ( sit-ups ) ( mean 0.62 stages , p = 0.003 ) and physical activity ( mean , 3253 steps/day , p < 0.001 ) . There were no group by time effects for the other muscular fitness measures . CONCLUSIONS A primary school-based intervention focusing on fitness education significantly improved health-related fitness and physical activity levels in children Abstract The purpose of this study was to investigate by direct measurement the cross-sectional relationship between accelerometer-measured physical activity and peak oxygen uptake ( [Vdot]O2peak : ml · min−1 · kg−1 ) , in a population -based cohort of young children , since such data are scarce . The study included 468 children ( 246 boys , 222 girls ) aged 6.7 ± 0.4 years , recruited from a population -based cohort . Peak oxygen uptake was measured by indirect calorimetry during a maximal treadmill exercise test . Physical activity was assessed by accelerometers over a 4-day period . Minutes of sedentary , light , moderate , moderate-to-vigorous , and vigorous activity per day were calculated . Mean counts per minute were considered to reflect total physical activity . Pearson correlation coefficients indicated a weak relationship between daily physical activity variables and [Vdot]O2peak in boys ( r = 0.15–0.28 , P < 0.05 ) , with the exception of time in sedentary and light activity , which was not related to [Vdot]O2peak . None of the daily physical activity variables were related to [Vdot]O2peak in girls , with the exception of a very weak relationship for moderate activity ( r = 0.14 , P < 0.05 ) . Multiple regression analyses indicated that the various physical activity variables explained between 2 and 8 % of the variance in [Vdot]O2peak in boys . In this population -based cohort , most daily activity variables were positively related to aerobic fitness in boys , whereas less clear relationships were observed in girls . Our finding  that physical activity was only uniformly related to aerobic fitness in boys partly contradicts previous studies in older children and adolescents
target: Overall , total PA was favourably associated with physical , psychological/social , and cognitive health indicators .
  Relationships were more consistent and robust for higher ( e.g. , MVPA ) versus lower ( e.g. , LPA ) intensity PA .
  All patterns of activity ( sporadic , bouts , continuous ) provided benefit .
  LPA was favourably associated with cardiometabolic biomarkers ; data were scarce for other outcomes .
  These findings continue to support the importance of at least 60 min/day of MVPA for disease prevention and health promotion in children and youth , but also highlight the potential benefits of LPA and total PA .
background: Moderate-to-vigorous physical activity ( MVPA ) is essential for disease prevention and health promotion .
  Emerging evidence suggests other intensities of physical activity ( PA ) , including light-intensity activity ( LPA ) , may also be important , but there has been no rigorous evaluation of the evidence .
  The purpose of this systematic review was to examine the relationships between objective ly measured PA ( total and all intensities ) and health indicators in school-aged children and youth .
  Online data bases were search ed for peer- review ed studies that met the a priori inclusion criteria : population ( apparently healthy , aged 5 - 17 years ) , intervention/exposure/comparator ( volumes , duration s , frequencies , intensities , and patterns of objective ly measured PA ) , and outcome ( body composition , cardiometabolic biomarkers , physical fitness , behavioural conduct/pro-social behaviour , cognition/academic achievement , quality of life/well-being , harms , bone health , motor skill development , psychological distress , self-esteem ) .