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Daily Quantity of Infant Leg Movement: Wearable Sensor Algorithm and Relationship to Walking Onset
Beth A Smith1, Ivan A Trujillo-Priego2, Christianne J Lane3
1Division of Biokinesiology and Physical Therapy, University of Southern California, Los Angeles, CA 90089-9006, USA. beth.smith@usc.edu.
Insights
Infants move their legs tens of thousands of times daily. More leg movements were linked to a later onset of independent walking in a small study, requiring further research.
Area of Science:
- Developmental Pediatrics
- Movement Science
Background:
- Normative data for infant leg movement quantity is currently unavailable.
- Understanding leg movement quantity is crucial for infant walking onset and early intervention.
- Lack of data hinders identification of developmental delays in infants.
Purpose of the Study:
- To establish normative values for daily infant leg movements.
- To investigate the relationship between leg movement quantity and the onset of independent walking.
- To explore the utility of wearable sensors for capturing infant movement data.
Main Methods:
- Utilized wearable inertial movement sensors to record leg activity in 12 typically developing infants (1-12 months).
- Collected full-day movement data across three sessions over 5 months, tracking infants until independent walking.
- Developed and validated an algorithm to accurately identify and quantify infant leg movements.
Main Results:
- Typically developing infants exhibit tens of thousands of leg movements daily.
- A significant association was found between higher leg movement quantity and later walking onset.
- Infants with more leg movements walked later, even after accounting for age and developmental factors.
Conclusions:
- Wearable sensors can reliably capture daily infant leg movements in the home environment.
- A correlation exists between leg movement quantity and walking onset in typically developing infants.
- Further investigation with larger sample sizes is needed to fully elucidate the observed relationship and its implications.
Background:
Normative values are lacking for daily quantity of infant leg movements. This is critical for understanding the relationship between the quantity of leg movements and onset of independent walking, and will begin to inform early therapy intervention for infants at risk for developmental delay.
Methods:
We used wearable inertial movement sensors to record full-day leg movement activity from 12 infants with typical development, ages 1-12 months. Each infant was tested three times across 5 months, and followed until the onset of independent walking. We developed and validated an algorithm to identify infant-produced leg movements.
Results:
Infants moved their legs tens of thousands of times per day. There was a significant effect of leg movement quantity on walking onset. Infants who moved their legs more walked later than infants who moved their legs less, even when adjusting for age, developmental level or percentile length. We will need a much larger sample to adequately capture and describe the effect of movement experience on developmental rate. Our algorithm defines a leg movement in a specific way (each pause or change in direction is counted as a new movement), and further assessment of movement characteristics are necessary before we can fully understand and interpret our finding that infants who moved their legs more walked later than infants who moved their legs less.
Conclusions:
We have shown that typically-developing infants produce thousands of leg movements in a typical day, and that this can be accurately captured in the home environment using wearable sensors. In our small sample we can identify there is an effect of leg movement quantity on walking onset, however we cannot fully explain it.
