Results Physical activity was associated with numerous health benefits .
The dose-response relations observed in observational studies indicate that the more physical activity , the greater the health benefit .
Results from experimental studies indicate that even modest amounts of physical activity can have health benefits in high-risk youngsters ( e.g. , obese ) .
Vigorous intensity activities may provide even greater benefit .
Aerobic-based activities had the greatest health benefit , other than for bone health , in which case high-impact weight bearing activities were required .
Some of the health benefits can be achieved through an average of 30 minutes per day . [
Level 2 , Grade A ] .
Background The purpose was to : 1 ) perform a systematic review of studies examining the relation between physical activity , fitness , and health in school-aged children and youth , and 2 ) make recommendations based on the findings .
A randomized school-based jumping intervention confers site and maturity-specific benefits on bone structural properties in girls: a hip structural analysis study.
We compared 7-month changes in bone structural properties in pre- and early-pubertal girls r and omized to exercise intervention ( 10-minute , 3 times per week , jumping program ) or control groups .  Girls were classified as prepubertal ( PRE ; Tanner breast stage 1 ; n = 43 for intervention [ I ] and n = 25 for control [ C ] ) or early-pubertal ( EARLY ; Tanner stages 2 and 3 ; n = 43 for I and n = 63 for C ) . Mean + /- SD age was 10.0 + /- 0.6 and 10.5 + /- 0.6 for the PRE and EARLY groups , respectively . Proximal femur scans were analyzed using a hip structural analysis ( HSA ) program to assess bone mineral density ( BMD ) , subperiosteal width , and cross-sectional area and to estimate cortical thickness , endosteal diameter , and section modulus at the femoral neck ( FN ) , intertrochanter ( IT ) , and femoral shaft ( FS ) regions . There were no differences between intervention and control groups for baseline height , weight , calcium intake , or physical activity or for change over 7 months ( p > 0.05 ) . We used analysis of covariance ( ANCOVA ) to examine group differences in changes of bone structure , adjusting for baseline weight , height change , Tanner breast stage , and physical activity . There were no differences in change for bone structure in the PRE girls . The more mature girls ( EARLY ) in the intervention group showed significantly greater gains in FN ( + 2.6 % , p = 0.03 ) and IT ( + 1.7 % , p = 0.02 ) BMD . Underpinning these changes were increased bone cross-sectional area and reduced endosteal expansion . Changes in subperiosteal dimensions did not differ . Structural changes improved section modulus ( bending strength ) at the FN ( + 4.0 % , p = 0.04 ) , but not at the IT region . There were no differences at the primarily cortical FS . These data provide insight into geometric changes that underpin exercise-associated gain in bone strength in early-pubertal girls
Results Physical activity was associated with numerous health benefits .
The dose-response relations observed in observational studies indicate that the more physical activity , the greater the health benefit .
Results from experimental studies indicate that even modest amounts of physical activity can have health benefits in high-risk youngsters ( e.g. , obese ) .
Vigorous intensity activities may provide even greater benefit .
Aerobic-based activities had the greatest health benefit , other than for bone health , in which case high-impact weight bearing activities were required .
Some of the health benefits can be achieved through an average of 30 minutes per day . [
Level 2 , Grade A ] .
Background The purpose was to : 1 ) perform a systematic review of studies examining the relation between physical activity , fitness , and health in school-aged children and youth , and 2 ) make recommendations based on the findings .