Tracking physical activity and sedentary behavior in young children.

Tracking of total physical activity (PA), moderate to vigorous activity (MVPA), and sedentary behavior was assessed in 42 young children (mean age at baseline 3.8 years) over a 2-year period using the Actigraph accelerometer. Tracking was analyzed using Spearman rank correlations, percentage agreements, and kappa statistics. Spearman rank correlations were r = .35 (p = .002) for total PA, r = .37 (p = .002) for MVPA, and r = .35 (p = .002) for sedentary behavior. Percentage agreements for PA, MVPA, and sedentary behavior were 38, 41, and 26 respectively. Kappa statistics for PA, MVPA, and sedentary behavior ranged from poor to fair. Results suggest low levels of tracking of total physical activity, MVPA, and sedentary behavior in young Scottish children over a 2-year period.

Parental feeding style, energy intake and weight status in young Scottish children.

Parental feeding style, as measured by the Child Feeding Questionnaire (CFQ), may be an important influence on child feeding behaviour and weight status in early to mid childhood, but more evidence on parental feeding style is required from samples outside the USA. We aimed to use the CFQ in a sample of 117 Scottish children (boys n 53, girls n 64 mean age 4.6 (SD 0.5) years) to: characterise gender differences and changes over time (in forty of the 117 children studied over 2 years); test associations between parental feeding style, free-living energy intake (measured over 3 days using the multiple pass 24-h recall), and weight status (BMI SD score). No dimensions of parental feeding style changed significantly over 2 years in the longitudinal study (P>0.05 in all cases). No aspects of parental feeding style as measured by the CFQ differed significantly between the sexes (P>0.05 in all cases). Parental perceptions of child weight status were generally significantly positively correlated with child weight status as measured by the BMI SD score. In this sample and setting, measures of parental control over child feeding were generally not associated with child energy intake or weight status.

Physical activity to prevent obesity in young children: cluster randomised controlled trial.

OBJECTIVE: To assess whether a physical activity intervention reduces body mass index in young children. DESIGN: Cluster randomised controlled single blinded trial over 12 months. SETTING: Thirty six nurseries in Glasgow, Scotland. PARTICIPANTS: 545 children in their preschool year, mean age 4.2 years (SD 0.2) at baseline. INTERVENTION: Enhanced physical activity programme in nursery (three 30 minute sessions a week over 24 weeks) plus home based health education aimed at increasing physical activity through play and reducing sedentary behaviour. MAIN OUTCOME MEASURE: Body mass index, expressed as a standard deviation score relative to UK 1990 reference data. Secondary measures were objectively measured physical activity and sedentary behaviour; fundamental movement skills; and evaluation of the process. RESULTS: Group allocation had no significant effect on the primary outcome measure at six and 12 months or on measures of physical activity and sedentary behaviour by accelerometry. Children in the intervention group had significantly higher performance in movement skills tests than control children at six month follow-up (P=0.0027; 95% confidence interval 0.3 to 1.3) after adjustment for sex and baseline performance. CONCLUSIONS: Physical activity can significantly improve motor skills but did not reduce body mass index in young children in this trial. TRIAL REGISTRATION: Current Controlled Trials ISRCTN36363490.

Validation of Actigraph accelerometer estimates of total energy expenditure in young children.

PURPOSE: To assess the validity of two equations based on the Actigraph CSA/MTI accelerometer for prediction of total energy expenditure (TEE). RESEARCH METHODS AND PROCEDURES: The criterion was TEE measured using the doubly labeled water method in 85 children, mean age 4.6 years (SD 1.1), over 7 days in the pre-schoolers and 10 days in the school-age participants. Children wore the Actigraph concurrently during waking hours, for 3 of 7 days (pre-schoolers) or 7 of 10 days (school-age children). We tested two prediction equations based on accelerometry. Agreement between predicted and measured TEE was assessed using the 'Bland Altman' approach. RESULTS: Mean TEE measured by doubly-labeled water was 5.8 MJ/d (SD 1.6). Mean error for the Ekelund equation was + 0.3 MJ/d (limits of agreement -3.7 to + 4.3), and for that of Puyau et al. was -0.3 MJ/d (limits of agreement + 3.2 to -3.8). CONCLUSIONS: Simple approaches using the Actigraph appear to be inadequate for the estimation of free-living TEE in young children at present.

Monitoring of Physical Activity in Young Children: How Much Is Enough?

There is limited evidence on how much and on which days accelerometry monitoring should be performed to obtain a representative measurement of physical activity (PA) in young children. We measured 76 children (40 M and 36 F, mean age 5.6 years ([SD ± 0.4]) on 7 days using Actigraph accelerometers. Mean daily PA was expressed in counts per min (cpm). Reliability increased as the number of days and hours of monitoring increased, but only to 10 hr per day. At 7 days of monitoring for 10 hr per day, reliability was 80% (95% CI [70%, 86%]). The number of days was more important to reliability than the number of hours. The inclusion or exclusion of weekend days made relatively little difference. A monitoring period of 7 days for 10 hr per day produced the highest reliability. Surprisingly short monitoring periods may provide adequate reliability in young children.

Validation of energy intake by 24-hour multiple pass recall: comparison with total energy expenditure in children aged 5-7 years.

Accurate measurement of energy intake (EI) is essential in studies of energy balance in all age groups. Reported values for EI can be validated against total energy expenditure (TEE) measured using doubly labelled water (DLW). Our previous work has indicated that the use of the standardized 24 h multiple pass recall (24 h MPR) method produces slight overestimates of EI in pre-school children which are inaccurate at individual level but acceptable at group level. To extend this work, the current study validated EI by 24 h MPR against TEE by DLW in sixty-three (thirty-two boys) school-aged children (median age 6 years). In both boys and girls, reported EI was higher than TEE, although this difference was only significant in the girls (median difference 420 kJ/d, P=0.05). On analysis of agreement between TEE and EI, the group bias was an overestimation of EI by 250 kJ/d with wide limits of agreement (-2880, 2380 kJ/d). EI was over-reported relative to TEE by 7 % and 0.9 % in girls and boys, respectively. The bias in the current study was lower than in our previous study of pre-school children, suggesting that estimates of EI become less inaccurate as children age. However, the current study suggests that the 24 h MPR is inaccurate at the individual level.

Fundamental movement skills and habitual physical activity in young children.

PURPOSE: To test for relationships between objectively measured habitual physical activity and fundamental movement skills in a relatively large and representative sample of preschool children. METHODS: Physical activity was measured over 6 d using the Computer Science and Applications (CSA) accelerometer in 394 boys and girls (mean age 4.2, SD 0.5 yr). Children were scored on 15 fundamental movement skills, based on the Movement Assessment Battery, by a single observer. RESULTS: Total physical activity (r=0.10, P<0.05) and percent time spent in moderate to vigorous physical activity (MVPA) (r=0.18, P<0.001) were significantly correlated with total movement skills score. Time spent in light-intensity physical activity was not significantly correlated with motor skills score (r=0.02, P>0.05). CONCLUSIONS: In this sample and setting, fundamental movement skills were significantly associated with habitual physical activity, but the association between the two variables was weak. The present study questions whether the widely assumed relationships between motor skills and habitual physical activity actually exist in young children.

Relation between physical activity and energy expenditure in a representative sample of young children.

BACKGROUND: Strategies for the prevention and treatment of childhood obesity require a better understanding of the relation between the pattern of free-living physical activity and total energy expenditure (TEE). OBJECTIVE: We assessed the relations between TEE and physical activity level (PAL) during engagement in different intensities of physical activity. DESIGN: We used a cross-sectional study of 104 children (median age: 5.4 y) in Scotland. TEE was measured with use of doubly labeled water (DLW), and resting energy expenditure was predicted to determine PAL. Time spent sedentary and in light-intensity activity and in moderate- and vigorous-intensity physical activity (MVPA) was assessed by accelerometry concurrent with DLW measurements. Correlation and regression were used to assess the relations between measures of sedentary behavior, intensities of activity, and PAL as the dependent variable. RESULTS: Time spent sedentary was negatively correlated with PAL (r = -0.33, P < 0.01), and time spent in light-intensity activity was positively correlated with PAL (r = 0.31, P < 0.01). In multiple regression analyses, both time spent sedentary and in light-intensity activities were significantly associated with PAL. Time spent in MVPA was not associated with PAL; engagement in MVPA was limited in this sample (median: 3% of waking hours; range: 0-14%). PAL was significantly higher in boys than in girls. CONCLUSION: In this sample and setting, PAL was not influenced by engagement in MVPA but was influenced by time spent sedentary and in light-intensity activities. This study suggests that in young children, MVPA could make only a minor contribution to free-living TEE and PAL.

Maternal docosahexaenoic acid supplementation and fetal accretion.

Docosahexaenoic acid (DHA) (22 : 6n-3) is a polyunsaturated fatty acid that is an essential constituent of membranes, particularly of the nervous system. Infants acquire DHA from their mothers, either prenatally via the placenta or postnatally in milk. The present study aimed to test the hypothesis that maternal supplementation during the second and third trimesters of pregnancy enriches maternal and/or fetal DHA status. In a randomised, prospective, double-blind study 100 mothers received either fish-oil capsules containing 400 mg DHA/g (200 mg/d) (n 50), or placebo containing 810 mg oleic acid/g (400 mg/d) (n 50) from 15 weeks gestation until term. Venous blood samples were obtained from mothers at 15, 28 and 40 weeks, and from the umbilical cord at birth. Total fatty acids in plasma and erythrocytes were analysed by GC-MS. There were no significant differences between maternal groups in baseline DHA, as a proportion of total fatty acids (g/100 g total fatty acids) or concentration (nmol/ml), in plasma and erythrocytes. DHA concentrations in plasma at 28 weeks (P=0.02) and erythrocytes at both 28 weeks (P=0.03) and term (P=0.02) were 20 % higher in supplemented mothers than the placebo group. DHA accounted for a higher proportion of total fatty acids in erythrocytes of supplemented mothers at 28 weeks (P=0.003) and term (P=0.01). There were no significant differences between groups in DHA (g/100 g total fatty acids or nmol/l) in cord blood. Maternal DHA status was maximal in mid-trimester and declined to term, at a lower rate in supplemented compared with unsupplemented mothers. Maternal DHA supplementation significantly increases maternal DHA status and limits the last trimester decline in maternal status, aiding preferential transfer of DHA from mother to fetus.

Scotopic electroretinogram in term infants born of mothers supplemented with docosahexaenoic acid during pregnancy.

PURPOSE: To test the hypothesis that the supplementation of the diets of pregnant women with a fish oil rich in docosahexaenoic acid (DHA) enhances retinal development in their healthy term infants, as measured during the early postnatal period by the electroretinogram (ERG). METHODS: One hundred pregnant women were randomized to receive either a fish oil (n = 50) or a placebo oleic acid dietary supplement (n = 50) from 15 weeks of pregnancy until delivery. Total fatty acids in red blood cells (RBCs) and plasma were measured in mothers at 15 and 28 weeks of pregnancy and at delivery and in their infants in umbilical cord blood. Infant retinal development was assessed within the first week of life with full-field ERGs that included a scotopic blue intensity series (n = 41) and a bright white flash (2.0 log cd-s/m(2); n = 44). RESULTS: Infants born of mothers who received supplements did not differ at birth in weight, gestational age, or any other standard variable. Infant DHA status at birth, as measured from umbilical cord blood, did not differ significantly between maternal supplementation groups. ERG implicit times, amplitudes, and parameters of the stimulus-response function did not differ significantly between infants in the maternal supplemented and placebo groups. There was, however, a relationship between infant DHA status and maturity of the retina at birth, regardless of maternal supplementation group. A measure of retinal sensitivity (log sigma) correlated significantly (P < 0.005) with DHA status (as a percentage of total fatty acid; TFA) in infant cord blood. Infants in the highest quartile for cord blood DHA had higher retinal sensitivity compared with infants in the lowest quartile. Infants in the highest quartile for plasma DHA, both as a percentage of TFA and concentration, were born at a significantly later gestational age than were infants in the lower quartiles. CONCLUSIONS: These findings demonstrate an association between the DHA status of term infants and retinal sensitivity, suggesting an essential role of this long-chain polyunsaturated fatty acid (LCPUFA) in the development and function of the retina. However, maternal DHA status was not significantly associated with infant retinal sensitivity and no direct effect of maternal supplementation was observed.

Objectively measured physical activity in a representative sample of 3- to 4-year-old children.

OBJECTIVE: This study aimed to describe levels of physical activity in a representative sample of preschool children and to quantify tracking of activity over 1 year. RESEARCH METHODS AND PROCEDURES: Physical activity (mean accelerometry counts/minute) was assessed over 3 days using the Computer Science and Applications accelerometer in 3- to 4-year-old children (n = 104; 52 boys; mean age, 3.7 +/- 0.4 years). In 60 children (30 boys), measurements were repeated 1 year later. RESULTS: Mean total activity at baseline was 777 +/- 207 counts/minute in boys and 657 +/- 172 counts/minute for girls; this gender difference was significant (p < 0.001). In the cross-sectional analysis, total activity was significantly positively related to age (r = 0.37, p = 0.007). In the sample followed up for 1 year, mean total activity was 849 +/- 252. The longitudinal analysis confirmed that total physical activity increased over the 1-year period (paired Student's t test, p < 0.001). The tracking rank order correlation coefficient of total activity count over 1 year was r = 0.40 (p < 0.001). DISCUSSION: This study suggests that total activity increases during the preschool period in Scottish children and that gender differences in total activity are present early in life. Tracking of total activity was only modest, but adequate assessment of tracking requires methodological research aimed at elucidating the biological meaning of accelerometer output.