Examining accelerometer validity for estimating physical activity in pre-schoolers during free-living activity

Area of Science:

• Pediatric Exercise Science
• Biomedical Engineering
• Physical Activity Measurement

Background:

• Accurate assessment of physical activity in preschoolers is crucial for understanding health behaviors.
• Accelerometers are widely used but their validity in young children, particularly during free play, requires further investigation.
• Epoch length and wear location can influence accelerometer-derived physical activity data.

Purpose of the Study:

• To evaluate the efficacy of accelerometers (ActiGraph GT3X) for assessing free play physical activity in 3-4-year-old children.
• To determine the impact of different epoch lengths and wear locations (hip vs. wrist) on accelerometer validity.
• To compare accelerometer data with direct observation (OSRAC-P) for sedentary behavior (SB), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA).

Main Methods:

• Sixty-six preschoolers (3-4 years) wore accelerometers on their non-dominant wrist and right hip during a 1-hour free play session.
• Direct observation using OSRAC-P was employed concurrently to categorize activity intensity.
• Receiver operating curve (ROC) analysis was used to assess the predictive ability of accelerometer data (vertical axis counts and vector magnitude) across various epoch lengths (5-30 seconds).

Main Results:

• Accelerometers demonstrated fair agreement (AUC ≥ 0.7) with direct observation for sedentary behavior and moderate-to-vigorous physical activity, irrespective of wear location.
• Agreement for light physical activity was poor (AUC = 0.53-0.56) for both hip and wrist placements.
• Specificity for LPA was weak (0.34-0.43), while sensitivity was fair (0.74-0.84).

Conclusions:

• The ActiGraph is a fair measure for assessing sedentary behavior and moderate-to-vigorous physical activity in preschool children during free play.
• Neither wrist nor hip placement demonstrated superior performance across different epochs or data types (vertical axis, VM).
• Further research is needed to improve the accuracy of accelerometer-based light physical activity measurement in this age group.