Accelerometer Data Processing and Energy Expenditure Estimation in Preschoolers

Area of Science:

• Pediatric physiology
• Biomedical engineering
• Physical activity research

Background:

• Accurate measurement of energy expenditure in children is crucial for understanding health and activity levels.
• Wrist-worn accelerometers are commonly used to estimate physical activity and energy expenditure.
• Traditional metrics from accelerometers may not fully capture the nuances of movement in young children.

Purpose of the Study:

• To evaluate the efficacy of various wrist accelerometer-derived metrics in estimating total energy expenditure (TEE) and activity energy expenditure (AEE) in preschool children.
• To compare the performance of novel acceleration metrics against standard ActiGraph activity counts.

Main Methods:

• Thirty-nine preschoolers (5.5 ± 0.1 years) participated.
• Total energy expenditure (TEE) was measured using the doubly labeled water method over 14 days.
• Activity energy expenditure (AEE) was calculated using predicted basal metabolic rate.
• Participants wore a wGT3X-BT accelerometer on their wrist for at least 5 days.
• Raw acceleration data were used to derive metrics including ActiGraph counts, Euclidian norm minus 1g (ENMO), and other advanced summary metrics.

Main Results:

• Novel metrics, such as ENMO, explained a greater proportion of variance in TEE (13%-16%) and AEE (35%-39%) compared to ActiGraph counts (7%-8% for TEE, 25% for AEE).
• ENMO, adjusted for body weight and height, explained 51% of AEE variance.
• Metrics adjusted for fat mass and fat-free mass explained up to 84% of TEE and 67% of AEE variance.

Conclusions:

• Alternate summary metrics, particularly ENMO, demonstrate superior capacity in estimating TEE and AEE in preschool children compared to traditional ActiGraph counts.
• These findings advocate for the use and further investigation of advanced accelerometer metrics in pediatric physical activity and energy expenditure research.
• Further validation in diverse populations with broader age ranges and varied body compositions is recommended.