Relations of moderate and vigorous physical activity to fitness and fatness in adolescents. Prospective association between body composition, physical activity and energy intake in young adults Fatness leads to inactivity, but inactivity does not lead to fatness: a longitudinal study in children (EarlyBird 45) Regular participation in sports is associated with enhanced physical fitness and lower fat mass in prepubertal boys Effects of Changes in Adiposity and Physical Activity on Preadolescent Insulin Resistance: The Australian LOOK Longitudinal Study The impact of a 3-year after-school obesity prevention program in elementary school children. Preliminary findings of the effect of a 3-year after-school physical activity intervention on fitness and body fat: the Medical College of Georgia Fitkid Project. Challenge! Health Promotion/Obesity Prevention Mentorship Model Among Urban, Black Adolescents A 10-Month Physical Activity Intervention Improves Body Composition in Young Black Boys Infrequent Breakfast Consumption Is Associated with Higher Body Adiposity and Abdominal Obesity in Malaysian School-Aged Adolescents Dietary Intervention Causes Redistribution of Zinc in Obese Adolescents Effects of exercise intensity on cardiovascular fitness, total body composition, and visceral adiposity of obese adolescents. Impact of Weight Loss on Physical Function with Changes in Strength, Muscle Mass, and Muscle Fat Infiltration in Overweight to Moderately Obese Older Adults: A Randomized Clinical Trial Aging, body composition, and lifestyle: the Fels Longitudinal Study. Left ventricular structure and function in obese adolescents: relations to cardiovascular fitness, percent body fat, and visceral adiposity, and effects of physical training. Increased physical activity and reduced adiposity in overweight Hispanic adolescents. Intervening to Reduce Sedentary Behaviors and Childhood Obesity among School-Age Youth: A Systematic Review of Randomized Trials Age- and maturity-related changes in body composition during adolescence into adulthood: The Fels Longitudinal Study A haplotype of three SNPs in FTO had a strong association with body composition and BMI in Iranian male adolescents
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 Background / Objectives : Despite considerable research on the association between physical activity ( PA ) and body composition , there remains limited information on the directionality of the relationship . The present study examined the prospect i ve associations among objective ly measured PA , energy intake ( EI ) and body composition . Subjects/ Methods : A convenience sample of 430 adults ( 49 % male ) between 21 and 35 years of age was followed over 1 year with repeated measurements taken every 3 months . BMI ( kg/m2 ) and percent body fat ( % BF ) were calculated based on anthropometric measurements and dual energy X-ray absorptiometry . A multi-sensor device was worn over a period of 10 days to estimate total daily energy expenditure and time spent in different intensities . EI was calculated based on change in body composition and total daily energy expenditure . Results : A total of 379 participants provided valid data . On average , participants experienced a significant weight gain of 1.2±4.3 kg during the 12-month observation period , which was associated with an increase in % BF ( 0.8±3.2 % ) . Average time spent in moderate-to-vigorous PA ( MVPA ) decreased significantly , whereas EI remained constant . Optimal linear mixed models , adjusting for age and sex , showed an inverse effect of MVPA on BMI and % BF , whereas EI only directly affected BMI ( P<0.001 ) . There was also a significant inverse effect of BMI and % BF on MVPA ( P<0.001 ) . Conclusions : Results of this study indicate an inverse reciprocal association between MVPA and measures of adiposity . Thus , primary preventive actions are warranted to avoid excess weight gain , which may result in a vicious cycle of weight gain and low PA Objective To establish in children whether inactivity is the cause of fatness or fatness the cause of inactivity . Design A non-intervention prospect i ve cohort study examining children annually from 7 to 10 years . Baseline versus change to follow-up associations were used to examine the direction of causality . Setting Plymouth , Engl and . Participants 202 children ( 53 % boys , 25 % overweight/obese ) recruited from 40 Plymouth primary schools as part of the EarlyBird study . Main outcome measures  Physical activity ( PA ) was measured using Actigraph accelerometers . The children wore the accelerometers for 7 consecutive days at each annual time point . Two components of PA were analysed : the total volume of PA and the time spent at moderate and vigorous intensities . Body fat per cent ( BF% ) was measured annually by dual energy x ray absorptiometry . Results BF% was predictive of changes in PA  over the following 3 years , but PA levels were not predictive of subsequent changes in BF% over the same follow-up period . Accordingly , a 10 % higher BF% at age 7 years predicted a relative decrease in daily moderate and vigorous intensities of 4 min from age 7 to 10 years ( r=−0.17 , p=0.02 ) , yet more PA at 7 years did not predict a relative decrease in BF% between 7 and 10 years ( r=−0.01 , p=0.8 ) . Conclusions Physical inactivity appears to be the result of fatness rather than its cause . This reverse causality may explain why attempts to tackle childhood obesity by promoting PA have been largely unsuccessful OBJECTIVE : To study the effect of physical activity on whole body fat ( BF ) , its regional deposition and the influence of body fatness on physical performance in prepubertal children . DESSIGN : Cross-sectional study .SUBJECTS : A total of 114 boys ( 9.4±1.5 y , Tanner I – II ) , r and omly sample d from the population of Gran Canaria ( Spain ) , 63 of them physically active ( PA , at least 3 h per week during the previous year ) and 51 nonphysically active ( non-PA ) .  MEASUREMENTS : Body composition ( DXA ) , anthropometric variables ( body circumferences and skinfolds ) and physical fitness were determined in all subjects . RESULTS : The PA obtained better results in maximal oxygen uptake , isometric leg extension force , vertical jump ( muscular power ) , and 300 m ( anaerobic capacity ) and 30 m running tests ( speed ) than the non-PA . A lower percentage of body fat ( % BF ) ( 4 U less , P<0.05 ) , whole BF mass ( 36 % less , P<0.05 ) and regional fat mass ( 28 , 25 , and 30 % less in the trunk , legs and arms , respectively , all P<0.05 ) was observed in the PA compared to the non-PA . The waist and hip circumferences correlated more closely with both the fat mass accumulated in the trunk region and the % BF ( r=0.81–0.95 , P<0.001 ) than the waist-to-hip ratio ( WHR ) . The WHR correlated with the percentage of the whole fat mass accumulated in the trunk ( PFT ) ( r=0.52–0.53 , P<0.001 ) . In both groups , the PFT increased curvilinearly with the % BF , regardless of the level of physical activity . ANCOVA analysis revealed that total and regional fat masses explained less than 40 % of the difference in performance between the PA and non-PA group . The mean speed in the 30 m running test ( V30 ) , combined with the height and whole body mass , has predictive value for the BF mass ( R=0.98 , P<0.001 ) . The % BF may be estimated from the body mass index ( BMI ) and V30 ( % BF=8.09 + 2.44 · BMI ( kg m−2)–5.8·V30 ( m s−1 ) , R=0.94 , P<0.001 ) in prepubertal boys . CONCLUSIONS : Regular participation in at least 3 h per week of sports activities and competitions on top of the compulsory physical education program is associated with increased physical fitness , lower whole body and trunkal fat mass in prepubertal boys 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 BACKGROUND Children tend to be sedentary during the after-school hours , and this has deleterious effects on their health . The objective of the present study was to determine the effects of a 3-year after-school physical activity ( PA ) program , without restriction of dietary energy intake , on percent body fat ( % BF ) , cardiorespiratory fitness ( CRF ) , and cardiometabolic markers in children . METHODS A cluster r and omization design was employed . A total of 574 3rd grade children from 18 elementary schools in the southeastern United States participated . The intervention consisted of 80 minutes of age-appropriate moderate-to-vigorous PA each school day . The main outcomes of interest were % BF measured by dual-energy X-ray absorptiometry ; CRF measured by heart rate in response to a submaximal step test ; nonfasting total and high-density lipoprotein cholesterol ( HDL-C ) ; and resting blood pressure ( BP ) . RESULTS Intent-to-treat analyses showed significant treatment by time interactions for % BF ( p = 0.009 ) and CRF ( p = 0.0003 ) . The change pattern of the means suggested that % BF and CRF in intervention children improved relative to control children during the school months , rebounding to the levels of control children over the summers following years 1 and 2 . Year-by-year analyses of what occurred during the months when the program was offered revealed dose – response relations for % BF and CRF , such that the clearest beneficial effects were seen for those youth who attended at least 60 % of the after-school sessions . No significant intervention effects were seen for cholesterol or BP . CONCLUSIONS An after-school PA program was effective in reducing adiposity and improving CRF , especially in the children who attended the sessions at least 3 days/week . However , the favorable effects on % BF and CRF were lost over the summer . Thus , it is critical to incorporate strategies that attract and retain the children to receive an adequate dose of PA year-round OBJECTIVE To evaluate the effect of a 3-year after-school physical activity ( PA ) intervention on aerobic fitness and percent body fat ( % BF ) . METHODS In total , 18 schools were r and omized into intervention or control arms . Measurements were made at the beginning and end of the third , fourth and fifth grade s. Fitness was measured with heart rate response to a bench-stepping task.%BF and bone density were measured with dual-energy x-ray absorptiometry . The intervention included 40 min of academic enrichment activities , during which healthy snacks were provided , and 80 min of moderate-to-vigorous PA ( MVPA ) . RESULTS Data analyses were performed on 206 youths who remained in the same schools for the 3-year period , who were measured at all six time points and , for the intervention group , who attended at least 40 % of the sessions in each of the 3 years . The group by time interactions were significant for fitness ( p < 0.01 ) and % BF ( p < 0.05 ) . Children in intervention schools improved in fitness and % BF during the school years and returned to levels similar to those in control schools during the summers . Over the six measurement points , the intervention group increased more than the control group in bone density ( p < 0.01 ) , fat-free soft tissue ( p < 0.01 ) , weight ( p < 0.01 ) , height ( p < 0.01 ) , and body mass index ( p < 0.05 ) . CONCLUSIONS An after-school program focusing on MVPA had a beneficial effect on fitness and body composition . During the summers , the beneficial effect of the previous year 's participation on fitness and % BF was lost . This highlights the importance of year-round programs to promote healthy growth in youths OBJECTIVES : The objective of this study was to evaluate a 12-session home/community-based health promotion/obesity prevention program ( Challenge ! ) on changes in BMI status , body composition , physical activity , and diet . METHODS : A total of 235 black adolescents ( aged 11–16 years ; 38 % overweight/obese ) were recruited from low-income urban communities . Baseline measures included weight , height , body composition , physical activity ( PA ) , and diet . PA was measured by 7-day play-equivalent physical activity ( ≥1800 activity counts per minute ) . Participants were r and omly assigned to health promotion/obesity prevention that is anchored in social cognitive theory and motivational interviewing and was delivered by college-aged black mentors or to control . Postintervention ( 11 months ) and delayed follow-up ( 24 months ) evaluations were conducted . Longitudinal analyses used multilevel models with r and om intercepts and generalized estimating equations , controlling for baseline age/gender . Stratified analyses examined baseline BMI category . RESULTS : Retention was 76 % over 2 years ; overweight/obese status declined 5 % among intervention adolescents and increased 11 % among control adolescents . Among overweight/obese youth , the intervention reduced total percentage of body fat and fat mass and increased fat-free mass at delayed follow-up and increased play-equivalent physical activity at postintervention but not at delayed follow-up . Intervention adolescents declined significantly more in snack/dessert consumption than control adolescents at both follow-up evaluations . CONCLUSIONS : At postintervention , there were intervention effects on diet and PA but not BMI category or body composition . At delayed follow-up , dietary changes were sustained and the intervention prevented an increase in BMI category . Body composition was improved for overweight/obese youth . Changes in body composition follow changes in diet and PA and may not be detected immediately after intervention Objective . To determine if a 10-month after-school physical activity ( PA ) intervention could prevent deleterious changes in body composition and cardiovascular ( CV ) fitness in young black boys . Methods . Following baseline measures , 106 boys ( 8–12 yrs ) were r and omized to either a control group or an intervention group , further divided into attenders ( ATT ) and nonattenders ( NATT ) , participating in ≥60 % or < 60 % of the intervention , respectively . The daily intervention consisted of skills development ( 25 min ) , vigorous PA ( VPA , 35 min ) , and strengthening/stretching ( 20 min ) components . Body composition was measured by dual-energy X-ray absorptiometry . Results . Following the intervention , the ATT exhibited an increase in moderate-to-vigorous PA and a significant reduction in BMI , fat mass , and % BF compared to the control group . A significant association among the intervention energy expenditure and changes in body composition and CV fitness was observed only in the ATT group . Conclusion . An after-school PA program of sufficient length and intensity can promote healthy changes in body composition and fitness levels in black boys who attend at least 3 days/week Unhealthy dietary pattern increases the risk of obesity and metabolic disorders in growing children and adolescents . However , the way the habitual pattern of breakfast consumption influences body composition and risk of obesity in adolescents is not well defined . Thus , the aim of the present study was to assess any associations between breakfast consumption practice s and body composition profiles in 236 apparently healthy adolescents aged 12 to 19 years . A self-administered question naire on dietary behaviour and lifestyle practice s and a dietary food frequency question naire were used . Body composition and adiposity indices were determined using st and ard anthropometric measurement protocol s and dual energy χ-ray absorptiometry ( DXA ) .  Mean age of the participants was 15.3±1.9 years . The majority of participants ( 71.2 % ) fell in the normal body mass index ( BMI ) ranges . Breakfast consumption patterns showed that only half of the participants ( 50 % ) were consuming breakfast daily . Gender-specific multivariate analyses ( ANCOVA ) showed that in both boys and girls , those eating breakfast at least 5 times a week had significantly lower body weight , body mass index ( BMI ) , BMI z-scores , waist circumference , body fat mass and percent body fat ( % BF ) compared to infrequent breakfast eaters , after adjustment for age , household income , pubertal status , eating-out and snacking practice s , daily energy intakes , and daily physical activity levels . The present findings indicate that infrequent breakfast consumption is associated with higher body adiposity and abdominal obesity . Therefore , daily breakfast consumption with healthy food choices should be encouraged in growing children and adolescents to prevent adiposity during these critical years of growth Obese people tend to have low zinc circulation levels ; this is not always related to zinc intake but can reflect the distribution of zinc in relation to the proportion of body fat and factors related to the inflammatory processes that cause obesity . The purpose of this study was to assess zinc distribution in 15 obese adolescent girls before and after a nutritional orientation program . Participants ranged from 14 to 18 years old ( postpubescent ) and had a body fat percent ( BF% ) of > 35 % .  Zinc nutritional status and other zinc-dependent parameters , such as superoxide dismutase ( SOD ) and insulin levels , were assessed by biochemical analysis of plasma and erythrocytes , salivary sediment , and urine . Sample s were collected before and after 4 months of dietary intervention . Dual energy X-ray absorptiometry ( DXA ) was used to verify BF% both at the beginning and at the end of the study . Food consumption was assessed in ten individual food question naires throughout the study ; food groups were separated on the question naires in the same way as suggested by some authors to develop the Healthy Eating Index ( HEI ) but with the addition of zinc . After 4 months of nutritional orientation , 78 % of the participants showed a decrease in BF% . Intraerythrocytic zinc increased over the study period , while salivary sediment zinc , SOD , insulin , and Zn urinary24 h/creatinine all decreased ( p < 0.05 ) . There was no difference in zinc intake throughout the study but participants did increase their consumption of fruits , dairy , and meats during the study ( p < 0.05 ) . There were inverse and statistically significant correlations between the increased levels of intraerythrocytic zinc and decreased levels of SOD . There was also a statistically significant correlation between BF% and Zn urinary 24h/creatinine , and SOD . All these parameters were diminished at the end of the study . The dietary intervention for obese adolescent girls is effective with decrease of BF that led to the redistribution of zinc in the body as shown by the changes in erythrocytes , plasma , salivary , urine zinc , as well as the complementary parameters of insulin and SOD . These changes were not affected by zinc intake BACKGROUND Little is known about how the intensity of exercise influences cardiovascular fitness and body composition , especially in obese adolescents . OBJECTIVE Our goal was to determine the effects of physical training intensity on the cardiovascular fitness , percentage of body fat ( % BF ) , and visceral adipose tissue ( VAT ) of obese adolescents . DESIGN Obese 13 - 16-y-olds ( n = 80 ) were assigned to 1 ) biweekly lifestyle education ( LSE ) , 2 ) LSE + moderate-intensity physical training , or 3 ) LSE + high-intensity physical training . The intervention lasted 8 mo . Physical training was offered 5 d/wk , and the target energy expenditure for all subjects in physical training groups was 1047 kJ ( 250 kcal)/session . Cardiovascular fitness was measured with a multistage treadmill test , % BF with dual-energy X-ray absorptiometry , and VAT with magnetic resonance imaging . RESULTS The increase in cardiovascular fitness in the high-intensity physical training group , but not in the moderate-intensity group , was significantly greater than that in the LSE alone group ( P = 0.009 ) ; no other comparisons of the 3 groups were significant . Compared with the LSE alone group , a group composed of subjects in both physical training groups combined who attended training sessions > or=2 d/wk showed favorable changes in cardiovascular fitness ( P < 0.001 ) , % BF ( P = 0.001 ) , and VAT ( P = 0.029 ) . We found no evidence that the high-intensity physical training was more effective than the moderate-intensity physical training in enhancing body composition . CONCLUSIONS The cardiovascular fitness of obese adolescents was significantly improved by physical training , especially high-intensity physical training . The physical training also reduced both visceral and total-body adiposity , but there was no clear effect of the intensity of physical training Purpose . Evaluate the effects of weight loss on muscle mass and area , muscle fat infiltration , strength , and their association with physical function . Methods . Thirty-six overweight to moderately obese , sedentary older adults were r and omized into either a physical activity plus weight loss ( PA+WL ) or physical activity plus successful aging health education ( PA+SA ) program . Measurements included body composition by dual-energy X-ray absorptiometry , computerized tomography , knee extensor strength , and short physical performance battery ( SPPB ) . Results . At 6 months , PA+WL lost greater thigh fat and muscle area compared to PA+SA . PA+WL lost 12.4 % strength ; PA+SA lost 1.0 % . Muscle fat infiltration decreased significantly in PA+WL and PA+SA . Thigh fat area decreased 6-fold in comparison to lean area in PA+WL . Change in total SPPB score was strongly inversely correlated with change in fat but not with change in lean or strength . Conclusion . Weight loss result ed in additional improvements in function over exercise alone , primarily due to loss of body fat BACKGROUND Changes in body composition in men and women occur with age , but these changes are affected by numerous covariate factors . OBJECTIVE The study examined patterns of change in body composition and determined the effects of long-term patterns of change in physical activity in older men and women and in menopausal status and estrogen use in women . DESIGN Serial measures of height , weight , body mass index ( BMI ) , total body fat ( BF ) , percentage BF , and fat-free mass ( FFM ) from underwater weighing of 102 men and 108 women enrolled in the Fels Longitudinal Study were analyzed . Physical activity levels and menopausal status were included as covariates . RESULTS There were significant age-related decreases in FFM and height and increases in total BF , percentage BF , weight , and BMI . Physical activity was associated with decreases in total BF , percentage BF , weight , and BMI in men and were associated with increases in FFM and decreases in total BF and percentage BF in women . Postmenopausal women had significantly higher total BF and percentage BF than did pre- and perimenopausal women . The longer the time since menopause the greater were the increases in weight , BMI , total BF , and percentage BF ; however , estrogen use attenuated these increases . CONCLUSIONS Low FFM can be improved by increased physical activity . The effects of an intervention program on body composition can be masked if only body weight or BMI is measured . The effects of physical activity were more profound in postmenopausal than in premenopausal women , and estrogen use had beneficial effects on body composition OBJECTIVE Little is known about the relations of fitness and fatness to left ventricular structure and function in obese adolescents . This project had 2 purpose s : 1 ) to determine the correlations of cardiovascular fitness and adiposity to left ventricular parameters in obese adolescents ; and 2 ) to see the effect of 8 months of physical training ( PT ) at low and high intensities . DESIGN Obese 13- to 16-year-olds ( N = 81 ) were tested at baseline and then r and omly assigned to lifestyle education ( LSE ) alone , LSE plus moderate-intensity PT , or LSE plus high-intensity PT . Follow-up testing was conducted 8 months later . Because no significant differences were found between moderate-intensity and high-intensity PT , the groups were combined to form a LSE + PT group . INTERVENTION Eight months of PT , offered 5 days per week with the target energy expenditure for all PT participants being 250 kcal/session , and LSE every 2 weeks . Outcome Measures . Left ventricular mass divided by height to the 2.7th power ( LVM/Ht(2.7 ) ) , midwall fractional shortening ( MFS ) , and relative wall thickness ( RWT ) were measured using M-mode echocardiography . Cardiovascular fitness was measured by a maximal multistage treadmill test ; percent body fat ( % BF ) with dual-energy radiograph absorptiometry ; and visceral adipose tissue ( VAT ) with magnetic resonance imaging . RESULTS At baseline , high levels of VAT were associated with higher RWT ( r = 0.30 ) and lesser MFS ( r = -0.29 ) . Compared with the LSE-alone group , the LSE + PT group significantly improved in cardiovascular fitness and decreased in % BF and VAT . However , there were no significant differences between groups on changes in LVM/Ht(2.7 ) , MFS , or RWT . Individual changes in cardiovascular fitness , % BF , and VAT did not correlate significantly with interindividual changes in left ventricular structure and function . CONCLUSIONS High levels of VAT were associated with unfavorable left ventricular structure and function . However , no evidence was provided that an 8-month PT program , which improved cardiovascular fitness and reduced general and visceral adiposity , improved left ventricular structure and function . Future studies consisting of longer training programs and /or greater weight reductions are needed to see whether the adverse left ventricular effects of obesity can be ameliorated by exercise training PURPOSE The objectives of this study were to examine 1 ) whether changes in total physical activity  ( PA ; counts per minute , cpm ) and time spent in moderate to vigorous PA ( MVPA ) are associated with changes in adiposity and 2 ) whether energy intake influences the relationship between changes in PA and changes in adiposity in overweight Hispanic adolescents . METHODS Analysis included 38 overweight ( body mass index , > 85th percentile ) Hispanic adolescents with complete pretest and posttest data on relevant variables after participating in a 16-wk intervention . The intervention treatment did not influence PA , so the sample was combined and the r and omization group was adjusted for in the analysis . Body composition by dual-energy x-ray absorptiometry , 7-d PA by accelerometry , and dietary intake by 3-d diet records were assessed before and after intervention . RESULTS Within individuals , the mean increase of PA ( n = 19 ) and mean decrease of PA ( n = 19 ) was approximately 105 cpm . A 100-cpm increase in total PA was associated with a decrease of 1.3 kg of fat mass and 0.8 % body fat after adjusting for pretest adiposity , PA , age , sex , and treatment ( P < 0.05 ) . Controlling for energy intake modestly strengthened the relationships between total PA and fat mass and percent body fat . Changes in MVPA were not related to changes in adiposity after controlling for total PA ( P > 0.05 ) . CONCLUSIONS Increasing total PA  by 28 % ( 100 cpm ) was associated with a decrease of 1.4 kg of fat mass and 1 % body fat for 16 wk in overweight Hispanic adolescents independent of intervention group assignment . Increases in total PA , compared with MVPA , may be sufficient to improve body composition in overweight Hispanic adolescents Objective . To assess the effectiveness of interventions that focus on reducing  sedentary behavior ( SB ) among school-age youth and to identify elements associated with interventions ' potential for translation into practice setting s. Methods . A comprehensive literature search was conducted using 4 data bases for peer- review ed studies published between 1980 and April 2011 . R and omized trials , which lasted at least 12 weeks , aim ed at decreasing  SB among children aged 6 to 19 years were identified . Results . Twelve studies were included ; 3 focused only on SB , 1 focused on  physical activity ( PA )  , 6 were combined SB and PA interventions , and 2 studies targeted SB , PA , and diet .  The majority of the studies were conducted in a school setting , while others were conducted in such setting s as clinics , community centers , and libraries . Conclusions . Overall , interventions that focused on decreasing SB were associated with reduction in time spent on SB and /or improvements in anthropometric measurements related to childhood obesity . Several of the studies did consider elements related to the intervention 's potential for translation into practice setting OBJECTIVES : To examine patterns of change in total body fat ( TBF )  , percent body fat ( % BF ) , and fat-free mass ( FFM ) , from 8 - -20 y of age and the effect of rate of skeletal maturation . To determine the degree of tracking of body composition for individuals from childhood into adulthood . RESEARCH DESIGN : Annual serial data for TBF , % BF and FFM from underwater weighing using a multicomponent body composition model were collected from 130 CAUcasian males and 114 CAUcasian females between 1976 and 1996 . Rate of maturation was defined as FELS skeletal age ( SA ) less chronological age ( CA ) . R and om effects models were used to evaluate general patterns of change and tracking of individual serial data over the 12 y age range . RESULTS : Changes in TBF followed a quadratic model for males and for females with declining rates of change . Changes for % BF followed a cubic model for males and females . General patterns of change for FFM followed a cubic model for males and a quadratic model for females . TBF for males and females increased with age , but the rates of change declined with age . % BF for females increased from age 8–20 y. For males , % BF increased with age , but the positive rates of change declined and became a negative when aged about 13 y and reached a minimum at about the age of 15 y. The rate of change for % BF increased thereafter . FFM for males and females increased with age , but the rates of change decreased with age . The extent of tracking is inversely related to the length of the time interval . At the same age , rapidly-maturing children have significantly larger amounts of TBF , % BF and FFM than slow-maturing children . Tracking in body composition for individuals persisted from childhood to adulthood . CONCLUSIONS : ( 1 ) There are gender-associated differences in these patterns of change for % BF and FFM but not for TBF ; ( 2 ) TBF , % BF and FFM increased with increased rates of maturation ; ( 3 ) significant tracking in body composition for individuals persists from childhood to adulthood Background Single-nucleotide polymorphisms ( SNPs ) , which are located in the first intron of the FTO gene , are reported to be associated with body weight and the body mass index ( BMI ) . However , their effects on anthropometric measurements in adolescents are poorly understood . Objective This study aim ed to investigate the association of three adjacent polymorphisms ( rs9930506 , rs9930501 , & rs9932754 ) in the FTO gene with anthropometric indices in Iranian adolescent males . Design The participants comprised a total of 237 adolescent males who were recruited r and omly from two high schools in Tehran , Iran . The DNA sample s were genotyped for the FTO gene polymorphisms by DNA sequencing .  BMI , body fat percentage ( BF% ) , and body muscle percentage ( BM% ) were determined using a vali date d bioelectrical impedance analysis scale . The association of the FTO polymorphisms with weight , height , BMI , BF% , and BM% was investigated . Results A haplotype of rs9930506 , rs9930501 , and rs9932754 ( GGT ) in the first intron of the FTO with complete linkage disequilibrium ( LD ) was found to be significantly associated with higher weight ( OR = 1.32 ) , BMI ( OR = 5.36 ) and BF% ( OR = 1.46 ) , and lower BM% ( OR = 3.59 ) ( all P<0.001 ) . None of the students with GGC genotypes were underweight , while all of the students with AAT genotypes had high muscle mass . Conclusions A haplotype in the first intron of the FTO gene had a strong association with obesity indices in Iranian adolescent males . The FTO gene polymorphisms might have greater effects on anthropometric indices than what was previously imagined . Moreover , we suggested that the FTO gene exerted their effects on anthropometric measurements through haplotypes ( and not single SNPs )
Question naires were the more predominant way to evaluate PA .
Most studies showed that PA promotes a protective effect against a higher BF gain .
CONCLUSION It was concluded that PA has a protective effect against BF with differences between the genders and according to the BF marker or measurement assessed ; higher intensity PA leads to a greater effect against BF gain in both genders ; and the maintenance or increase of PA level on BF observed through analysis of change in PA level yielded more consistent findings in the relation between PA and BF
BACKGROUND Physical activity ( PA ) practice has been inversely associated to body  fat ( BF ) and recommended as a way to reduce and prevent obesity .
The objective of this study was to conduct a systematic review on the association of  PA and BF in adolescence .