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Validation and calibration of the activPAL™ for estimating METs and physical activity in 4-6 year olds
Xanne Janssen1, Dylan P Cliff1, John J Reilly2
1Interdisciplinary Educational Research Institute, University of Wollongong, Australia.
Insights
The activPAL™ equation needs improvement for estimating energy expenditure in preschoolers. A new threshold shows promise for classifying moderate-to-vigorous physical activity (MVPA) in young children.
Area of Science:
- Pediatric exercise science
- Physical activity measurement
- Biomedical engineering
Background:
- Accurate assessment of physical activity intensity is crucial for understanding children's health.
- The activPAL™ device is commonly used, but its metabolic equivalents (METs) equation may lack validity in preschoolers.
- Establishing reliable intensity thresholds is needed for this age group.
Purpose of the Study:
- To evaluate the predictive accuracy of the activPAL™ METs equation in 4- to 6-year-old children.
- To develop and validate a new activPAL™ threshold for defining moderate-to-vigorous physical activity (MVPA).
- To assess the classification accuracy of the developed MVPA threshold.
Main Methods:
- Forty 4- to 6-year-old children participated in a room calorimeter protocol.
- activPAL™ data (15s epochs) were collected alongside criterion measures of energy expenditure.
- A threshold for MVPA was developed and cross-validated using receiver operating characteristic (ROC) curve analysis.
Main Results:
- The activPAL™ METs equation significantly overestimated and underestimated METs across different activity intensities compared to criterion measures (P<0.001).
- A threshold of ≥1418 counts per 15s demonstrated good classification accuracy for MVPA.
- The developed threshold showed acceptable classification accuracy in this cohort.
Conclusions:
- The current activPAL™ METs equation is not sufficiently accurate for preschoolers.
- A newly developed activPAL™ threshold shows potential for identifying MVPA in young children.
- Further research is recommended to cross-validate this threshold in free-living conditions.
Objectives:
Examine the predictive validity of the activPAL™ metabolic equivalents equation, develop an activPAL™ threshold value to define moderate-to vigorous-intensity physical activities, and examine the classification accuracy of the developed moderate-to vigorous-intensity physical activities threshold value in 4- to 6-year-old children.
Design:
A sample of forty 4- to 6-year-old children from the Illawarra region in New South Wales, Australia were included in data analysis.
Methods:
Participants completed a ∼ 150-min room calorimeter protocol involving age-appropriate sedentary behaviors, light-intensity physical activities and moderate-to vigorous-intensity physical activities. activPAL™ accelerometer counts were collected over 15s epochs. Energy expenditure measured by room calorimetry and direct observation were used as the criterion measure. Predicted metabolic equivalents were calculated using the activPAL™ metabolic equivalents equation (activPAL™ software version 5.8.0). Predictive validity was evaluated using dependent-samples t-tests. Participants were randomly allocated into two groups to develop and cross-validate an intensity threshold for moderate-to vigorous-intensity physical activities. Receiver operating characteristic curve analysis was used to determine moderate-to vigorous-intensity physical activities threshold. The classification accuracy of the developed threshold was cross-validated using sensitivity, specificity, and area under the receiver operating characteristic-curve.
Results:
The activPAL™ metabolic equivalents equation significantly overestimated metabolic equivalents during sedentary behaviors and significantly underestimated metabolic equivalents for light-intensity physical activities, moderate-to vigorous-intensity physical activities and total metabolic equivalents compared to measured metabolic equivalents (all P<0.001). The developed threshold of ≥1418 counts per 15s resulted in good classification accuracy for moderate-to vigorous-intensity physical activities.
Conclusion:
The current activPAL™ metabolic equivalents equation requires further development before it can be used to accurately estimate metabolic equivalents in preschoolers. The developed threshold exhibited acceptable classification accuracy for moderate-to vigorous-intensity physical activities; however studies cross-validating this moderate-to vigorous-intensity physical activities threshold in free-living preschool-aged children are recommended.
