Abstract
BACKGROUND: Characteristics of movement can differentiate infants with typical development and infants with or at risk of developmental disabilities. We used wearable sensors to measure infants' typical movement patterns in the natural environment. OBJECTIVE: Our objectives were to determine (1) how many days were sufficient to represent an infant's typical daily performance, and (2) if there was a difference in performance between weekdays and weekend days. DESIGN: This was a prospective, observational study. METHODS: We used wearable sensors to collect 7 consecutive days of data for leg movement activity, from 10 infants with typical development (1-5 months old). We identified each leg movement, and its average acceleration, peak acceleration, and duration. Bland-Altman plots were used to compare the standard (average of 7 days) with 6 options (1 day, the average of days 1 and 2, through the average of days 1 through 6). Additionally, the average of the first 2 weekdays was compared with the average of 2 weekend days. RESULTS: The absolute difference between the average of the first 2 days and the standards fell below 10% of the standards (movement rate = 8.5%; duration = 3.7%; average acceleration = 2.8%; peak acceleration = 3.8%, respectively). The mean absolute difference between weekdays and weekends for leg movement rate, duration, average acceleration, and peak acceleration was 11.6%, 3.7%, 7.2%, and 7.3% of the corresponding standard. LIMITATIONS: The small sample size and age range limit extrapolation of the results. CONCLUSIONS: Our results suggest the best option is to collect data for 2 consecutive days and that movement did not differ between weekdays and weekend days. Our results will inform the clinical measurement of full-day infant leg movement for neuromotor assessment and outcome purposes.