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 .
Bone mass and structure are enhanced following a 2-year randomized controlled trial of exercise in prepubertal boys.
Exercise during growth has a positive influence on bone mineral accrual , yet little is known about how bone geometry and strength adapt to loading during growth . Our primary objective was to compare changes in proximal femur bone geometry and strength between 31 prepubertal ( Tanner Stage 1 ) boys who participated in a school-based , high-impact circuit intervention ( 12 min , three times a week ) for 20 months and 33 maturity-matched controls . Our secondary objective was to compare changes in total body ( TB ) , proximal femur ( PF ) , and lumbar spine ( LS ) bone mineral content ( BMC ) and bone area ( BA ) in these groups . We assessed geometric variables and bone strength at the narrow neck ( NN ) , intertrochanteric ( TR ) region , and femoral shaft regions by applying the Hip Structure Analysis program to proximal femur dual energy X-ray absorptiometry scans ( DXA , Hologic QDR 4500 ) . Further , we assessed total body , lumbar spine , and proximal femur BMC and BA by DXA and derived total body lean mass and fat mass from total body scans . Intervention ( 10.2 + /- 0.5 years ) and control boys ( 10.1 + /- 0.5 years ) had similar baseline height ( 140.8 vs. 141.3 cm ) and weight ( 36.9 vs. 35.4 kg ) , and average 20-month physical activity scores ( Physical Activity Question naire for Children , PAQ-C ) and calcium intakes ( 861 vs. 852 mg/day , food frequency question naire ) . Twenty-month height and weight changes were not significantly different between groups ; lean mass changed more ( P < 0.05 ) in intervention boys ( 22.8 % ) than control boys ( 18.6 % ) . At the NN region , intervention boys had greater bone expansion on both the periosteal ( + 2.6 % , P = 0.1 ) and endosteal ( + 2.7 % , P = 0.2 ) surfaces , result ing in significantly greater changes in section modulus ( bone bending strength ) ( + 7.5 % , P = 0.02 , ANCOVA , adjusting for height change , final Tanner Stage , and baseline bone values ) . Changes at the intertrochanteric and femoral shaft regions were not significantly different between groups . Femoral neck ( FN ) BMC changes were significantly greater in intervention boys ( + 4.3 % , P < 0.01 ) ; changes in BA and BMC for other regions were not significantly different between groups . In summary , a school-based , high-impact exercise intervention implemented three times a week for 12 min is an effective strategy for site-specific gains in bone strength at the narrow neck region of the proximal femur
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 .