Related Experiment Video
Updated: May 28, 2026
Measuring the Functional Abilities of Children Aged 3-6 Years Old with Observational Methods and Computer Tools
Published on: June 20, 2020
Validity, practical utility, and reliability of the activPAL™ in preschool children
Gwyneth Davies1, John J Reilly, Amy J McGowan
1School of Medicine, University of Glasgow, Glasgow, United Kingdom. gwyneth.davies1@imperial.ac.uk
Insights
The activPAL™ monitor shows good accuracy in measuring preschool children's sedentary time and activity. This tool is reliable for assessing posture and movement in young children.
Area of Science:
- Pediatric health
- Biomedical engineering
- Kinesiology
Background:
- Childhood obesity is a growing global concern.
- Accurate measurement of sedentary time is crucial for understanding energy balance in young children.
- Preschoolers have unique activity patterns requiring specific validation of measurement tools like the activPAL™.
Purpose of the Study:
- To validate the activPAL™ monitor for measuring posture and activity in preschool children.
- To assess the practical utility and reliability of the activPAL™ in this age group.
Main Methods:
- Thirty preschool children wore an activPAL™ monitor for one hour during nursery activities, with video recording as the criterion method.
- Video analysis categorized posture and activity second-by-second for comparison with activPAL™ data.
- A substudy involved 20 children wearing the monitor for seven consecutive 24-hour periods to assess utility and reliability.
Main Results:
- The activPAL™ demonstrated high sensitivity (86.7%-92.8%), specificity (97.1%-97.3%), and positive predictive value (96.3%-97.0%) for detecting "sit/lie" posture.
- The monitor slightly underestimated sitting time (-4.4%) and overestimated standing time (7.1%), with no significant difference for walking time.
- At least 5 days of monitoring were needed for reliable (ICC ≥ 0.8) assessment of "sit/lie" time.
Conclusions:
- The activPAL™ monitor is a valid, practical, and reliable tool for measuring posture and activity in preschool children during free-living conditions.
- This validates its use in research investigating factors contributing to childhood obesity.
Purpose:
With the increasing global prevalence of childhood obesity, it is important to have appropriate measurement tools for investigating factors (e.g., sedentary time) contributing to positive energy balance in early childhood. For preschool children, single-unit monitors such as the activPAL™ are promising. However, validation is required because activity patterns differ from adults.
Methods:
Thirty preschool children participated in a validation study. Children undertaking usual nursery activity while wearing an activPAL™ 1 h were recorded using a video camera. Video (criterion method) was analyzed on a second-by-second basis to categorize posture and activity. This was compared with the corresponding activPAL™ output. In a subsequent substudy investigating practical utility and reliability, 20 children wore an activPAL™ for seven consecutive 24-h periods.
Results:
A total of 97,750 s of direct observation from 30 children were categorized as sit/lie (46%), stand (35%), and walk (16%); with 3% of time in non-sit/lie/upright postures (e.g., crawl/crouch/kneel-up). Sensitivity for the overall total time-matched seconds detected as activPAL™ "sit/lie" was 86.7%, specificity was 97.1%, and positive predictive value was 96.3%. For individual children, the median (interquartile range) sensitivity for activPAL™ sit/lie was 92.8% (76.1%-97.4%), specificity was 97.3% (94.9%-99.2%), and positive predictive value was 97.0% (91.5%-99.1%). The activPAL™ underestimated total time spent sitting (mean difference = -4.4%, P < 0.01) and overestimated time standing (mean difference = 7.1%, P < 0.01). There was no difference in overall percent time categorized as "walk" (P = 0.2). The monitors were well tolerated by children during a 7-d period of free-living activity. In the reliability study, at least 5 d of monitoring was required to obtain an intraclass correlation coefficient of ≥ 0.8 for time spent "sit/lie" according to activPAL™ output.
Conclusions:
The activPAL™ had acceptable validity, practical utility, and reliability for the measurement of posture and activity during free-living activities in preschool children.
