Evaluation of the wrist-worn ActiGraph wGT3x-BT for estimating activity energy expenditure in preschool children.

BACKGROUND/OBJECTIVES: Easy-to-use and accurate methods to assess free-living activity energy expenditure (AEE) in preschool children are required. The aims of this study in healthy preschool children were to (a) evaluate the ability of the wrist-worn ActiGraph wGT3x-BT to predict free-living AEE and (b) assess wear compliance using a 7-day, 24-h protocol. SUBJECTS/METHODS: Participants were 40 Swedish children (5.5±0.2 years) in the Mobile-based intervention intended to stop obesity in preschoolers (MINISTOP) obesity prevention trial. Total energy expenditure (TEE) was assessed using the doubly labeled water method during 14 days. AEE was calculated as (TEEx0.9) minus predicted basal metabolic rate. The ActiGraph accelerometer was worn on the wrist for 7 days and outputs used were mean of the daily and awake filtered vector magnitude (mean VM total and mean VM waking). RESULTS: The ActiGraph was worn for 7 (n=34, 85%), 6 (n=4, 10%), 5 (n=1, 2.5%) and 4 (n=1, 2.5%) days (a valid day was ⩾600 awake minutes). Alone, mean VM total and mean VM waking were able to explain 14% (P=0.009) and 24% (P=0.001) of the variation in AEE, respectively. By incorporating fat and fat-free mass in the models 58% (mean VM total) and 62% (mean VM waking) in the variation of AEE was explained (P<0.001). CONCLUSIONS: The wrist-worn ActiGraph wGT3x-BT in combination with body composition variables explained up to the 62% of the variation in AEE. Given the high wear compliance, the wrist-worn ActiGraph has the potential to provide useful information in studies where physical activity in preschool children is measured.

Parental body mass index and its association with body composition, physical fitness and lifestyle factors in their 4-year-old children: results from the MINISTOP trial.

BACKGROUND/OBJECTIVES: To examine the association between parental body mass index (BMI) and their offspring's body composition, physical fitness and lifestyle factors (that is, sedentary time, physical activity and diet). SUBJECTS/METHODS: A total of 307 preschoolers (4.5±0.1 years) and their parents (fathers: 38.1±5.1 years and mothers: 35.6±4.2 years) participated in this study. Parental BMI was calculated using self-reported weight and height. Preschoolers body composition was assessed using: BMI, fat mass percentage, fat mass index, fat-free mass index (measured via air-displacement plethysmography) and waist circumference. Physical fitness was assessed by the PREFIT fitness battery. Lifestyle factors were assessed using the ActiGraph wGT3x-BT (sedentary time and physical activity), and the mobile-phone based tool for energy balance in children (diet). RESULTS: Parental BMI were positively associated with their offspring's BMI (paternal BMI: standardised beta, ß=0.233, P<0.001; maternal BMI: ß=0.186, P=0.001), fat mass index (paternal BMI: ß=0.130, P=0.026; maternal BMI: ß=0.163, P=0.005), fat-free mass index (paternal BMI: ß=0.214, P<0.001; maternal BMI: ß=0.119, P=0.036) and waist circumference (paternal BMI: ß=0.178, P=0.001; maternal BMI: ß=0.179, P=0.001). A negative association was found between maternal BMI and their offspring's standing long jump test (ß=-0.132, P=0.022). Paternal BMI was associated with their offspring's sedentary time (ß=0.100, P=0.026), whereas parental BMI was not associated with neither physical activity nor diet (all P⩾0.104). CONCLUSIONS: Parental BMI was positively associated with their offspring's BMI, fat as well as fat-free mass index and waist circumference. Moreover, a higher paternal and maternal BMI were related to higher levels of sedentary time and a lower performance in the standing long jump test of their offspring, respectively.