human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: 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 
    Output:
    
agent
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 .
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: 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 
    Output:
    