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 .
Relationships between physical activity, physical fitness, muscle strength and nutritional state in 5- to 11-year-old children
Abstract The purpose of the present study was to assess different aspects of physical activity and fitness in order to develop a basis for sport programmes for overweight and obese children . Eighty-eight prepubertal children ( 49 boys , 39 girls , 4.8–11.4 years old , 61 % obese , 14 % overweight and 25 % normal weight ) were examined . Body composition was assessed by combined use of anthropometrics and bioelectrical impedance analysis . Resting energy expenditure ( REE ) and total energy expenditure ( TEE ) were measured by indirect calorimetry ( IC ) and individually calibrated 24-h heart rate ( HR ) monitoring , respectively . Activity-related energy expenditure ( AEE ) and physical activity level ( PAL )  were calculated from TEE and REE .  Fitness [ assessed by O2-pulse , respiratory exchange ratio ( RER ) at submaximal work intensities ] was determined by ergometry . The maximal isometric muscle strength of the legs ( m. quadriceps , Fa max , m. ischiocruralis , Fb max ) was measured by computer tensiometry .  Children were grouped according to their nutritional state , AEE , O2-pulse and muscle strength . When compared with normal weight children , obese and overweight children had increased fat mass ( FM ) , fat-free mass ( FFM ) , waist-to-hip ratio and REE , but no group differences were observed for TEE , AEE , and PAL . Obese and overweight children spent more hours per day watching TV  . After correction for body weight and FFM , no group differences in REE were observed , but normal weight children had a higher O2-pulse than overweight and obese children . By contrast , RER was increased in the latter group . The fittest group had the lowest body weight , BMI , FM and FFM . Children with a low O2-pulse spent more hours per day watching TV . Grouping children according to their degree of muscle strength , younger children ( 4–7.5 years ) did not show group differences in nutritional state , energy expenditure , physical activity and fitness . However , in the group of 7.6- to 11-year-old children , those with the greatest muscle strength and FFM had reduced BMI , skin folds , FM and FFM . FM correlated inversely with O2-pulse , but was not associated with TEE , AEE , PAL or muscle strength . By contrast TV consumption was positively associated with FM . To summarize , overweight and obese children were less fit and watched more TV than their normal weight counterparts . FM did not correspond to TEE , AEE or PAL . Muscle strength was not associated with FM in young children , but was inversely associated with FM in older children . Our cross-sectional data are consistent with the idea that increased fitness and reduced physical inactivity may prevent children from being overweight
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 .