Results There was consistent evidence for a positive association between MF and physical activity .
For both MF components , there was support for objective ly measured physical activity , particularly for activity of vigorous intensity .
Sports participation was also consistently linked with both MF components , whereas the association with active transport was inconsistent .
For both MF components , associations with sedentary behaviors were inconsistent irrespective of measurement method , and the association between MF and sleep was considered uncertain .
Conclusions The available evidence supports a link between MF and physical activity , particularly for vigorous intensity activity and organized sports participation .
Background Muscular fitness ( MF ) is considered a powerful marker of health , but the extent to which common health behaviors are associated with MF during childhood and adolescence is currently unclear .
Objective We conducted a systematic review of studies investigating associations between MF ( i.e. , strength/power , local muscular endurance ) and physical activity , sedentary behaviors , and sleep in children and adolescents .
Effects of a daily school based physical activity intervention program on muscle development in prepubertal girls
This 12-month prospect i ve controlled intervention evaluated the effect of a general school based physical activity program on muscle strength , physical performance and body composition in prepubertal girls . Fifty-three girls aged 7–9 years involved in a school based exercise program [ 40 min/day of general physical activity per school day ( 200 min/week ) ] were compared with 50 age-matched girls who participated in the general Swedish physical education curriculum  ( mean 60 min/week ) . Body composition ( DXA ) , isokinetic peak torque ( PT ) of the knee extensors and flexors at 60 and 180 ° /s , and vertical jump height ( VJH ) were assessed at baseline and 12 months . The annual gain in weight was similar between the groups , but there was a greater increase in total body and regional lean mass ( P < 0.05 ) and fat mass ( P < 0.01 ) in the exercise group . Mean gains in knee extensor PT at 60 and 180 ° /s were 7.0–7.6 % greater in the exercise group ( P ranging < 0.05–<0.001 ) . No significant differences were detected in VJH . In conclusion , increasing school based physical education to at least 3 h/week provides a feasible strategy to enhance the development of muscle strength and lean mass in prepubertal girls
Results There was consistent evidence for a positive association between MF and physical activity .
For both MF components , there was support for objective ly measured physical activity , particularly for activity of vigorous intensity .
Sports participation was also consistently linked with both MF components , whereas the association with active transport was inconsistent .
For both MF components , associations with sedentary behaviors were inconsistent irrespective of measurement method , and the association between MF and sleep was considered uncertain .
Conclusions The available evidence supports a link between MF and physical activity , particularly for vigorous intensity activity and organized sports participation .
Background Muscular fitness ( MF ) is considered a powerful marker of health , but the extent to which common health behaviors are associated with MF during childhood and adolescence is currently unclear .
Objective We conducted a systematic review of studies investigating associations between MF ( i.e. , strength/power , local muscular endurance ) and physical activity , sedentary behaviors , and sleep in children and adolescents .