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Accelerometer Thresholds for Estimating Physical Activity Intensity Levels in Infants: A Preliminary Study
Mustafa A Ghazi1, Judy Zhou2, Kathryn L Havens2
1Division of Developmental-Behavioral Pediatrics, Children's Hospital Los Angeles, Los Angeles, CA 90027, USA.
Insights
This study establishes new accelerometer thresholds for measuring physical activity (PA) intensity in infants. These findings are crucial for monitoring early childhood activity levels and promoting healthy development.
Area of Science:
- Pediatrics
- Biomedical Engineering
- Kinesiology
Background:
- Lack of physical activity (PA) in early childhood is linked to significant health problems.
- Monitoring PA is essential for promoting healthy development in young children.
- Existing accelerometer thresholds for PA intensity are validated only for ambulatory children, not pre-ambulatory infants.
Purpose of the Study:
- To develop and validate accelerometer thresholds for classifying PA intensity levels (sedentary, light, moderate-to-vigorous) in pre-ambulatory infants.
- To establish reliable methods for objective PA monitoring in the earliest stages of life.
Main Methods:
- Ten infants participated, wearing accelerometers on each ankle while in a supine position with free movement.
- Video recordings served as the gold standard, with activity intensity labeled in two-second epochs.
- Accelerometer data (acceleration and jerk) were analyzed using two optimization approaches to derive thresholds.
Main Results:
- Four sets of thresholds were developed for both single and dual accelerometer use.
- Recommended acceleration-based thresholds for typical use: 1.00 m/s² (sedentary vs. light) and 2.60 m/s² (light vs. moderate-to-vigorous).
- Both acceleration and jerk measurements proved suitable for PA assessment in infants.
Conclusions:
- This research provides the first validated accelerometer thresholds for PA intensity in pre-ambulatory infants.
- These novel thresholds enable accurate objective monitoring of infant PA, supporting early health interventions.
- The findings contribute to a better understanding of physical activity patterns from the earliest developmental stages.
Abstract:
Lack of physical activity (PA) at a young age can result in health issues. Thus, monitoring PA is important. Wearable accelerometers are the preferred tool to monitor PA in children. Validated thresholds are used to classify activity intensity levels, e.g., sedentary, light, and moderate-to-vigorous, in ambulatory children. No previous work has developed accelerometer thresholds for infancy (pre-ambulatory children). Therefore, this work aims to develop accelerometer thresholds for PA intensity levels in pre-ambulatory infants. Infants (n = 10) were placed in a supine position and allowed free movement. Their movements were synchronously captured using video cameras and accelerometers worn on each ankle. The video data were labeled by activity intensity level (sedentary, light, and moderate-to-vigorous) in two-second epochs using observational rating (gold standard). Accelerometer thresholds were developed for acceleration and jerk using two optimization approaches. Four sets of thresholds were developed for dual (two ankles) and for single-worn (one ankle) accelerometers. Of these, for a typical use case, we recommend using acceleration-based thresholds of 1.00 m/s to distinguish sedentary and light activity and 2.60 m/s to distinguish light and moderate-to-vigorous activity. Acceleration and jerk are both suitable for measuring PA.
