Kids are not little adults: what MET threshold captures sedentary behavior in children? (original) (raw)

Abstract

Purpose

The study compares MET-defined cutpoints used to classify sedentary behaviors in children using a simulated free-living design.

Methods

A sample of 102 children (54 boys and 48 girls; 7–13 years) completed a set of 12 activities (randomly selected from a pool of 24 activities) in a random order. Activities were predetermined and ranged from sedentary to vigorous intensities. Participant’s energy expenditure was measured using a portable indirect calorimetry system, Oxycon mobile. Measured minute-by-minute VO2 values (i.e., ml/kg/min) were converted to an adult- or child-MET value using the standard 3.5 ml/kg/min or the estimated child resting metabolic rate, respectively. Classification agreement was examined for both the “standard” (1.5 adult-METs) and an “adjusted” (2.0 adult-METs) MET-derived threshold for classifying sedentary behavior. Alternatively, we also tested the classification accuracy of a 1.5 child-MET threshold. Classification accuracy of sedentary activities was evaluated relative to the predetermined intensity categorization using receiver operator characteristic curves.

Results

There were clear improvements in the classification accuracy for sedentary activities when a threshold of 2.0 adult-METs was used instead of 1.5 METs (Se1.5 METs = 4.7 %, Sp1.5 METs = 100.0 %; Se2.0 METs = 36.9 %, Sp2.0 METs = 100.0 %). The use of child-METs while maintaining the 1.5 threshold also resulted in improvements in classification (Se = 45.1 %, Sp = 100.0 %).

Conclusion

Adult-MET thresholds are not appropriate for children when classifying sedentary activities. Classification accuracy for identifying sedentary activities was improved when either an adult-MET of 2.0 or a child-MET of 1.5 was used.

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Abbreviations

AUC:

Area under the curve

CI:

Confidence interval

EE:

Energy expenditure

ICC:

Intraclass correlation

MET:

Metabolic equivalent

MVPA:

Moderate-to-vigorous physical activity

OM:

Oxycon mobile

PA:

Physical activity

REE:

Resting energy expenditure

ROC:

Receiver operating characteristic

Se:

Sensitivity

Sp:

Specificity

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Acknowledgments

No financial disclosures were reported by the authors of this paper. This work was funded by a grant received from the National Institute of Health, reference R01 HL091006.

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Authors and Affiliations

  1. Department of Kinesiology, Iowa State University, 235 Forker Building, Ames, IA, 50011, USA
    Pedro F. Saint-Maurice, Youngwon Kim & Gregory J. Welk
  2. School of Psychology: CIPsi, University of Minho, Braga, Portugal
    Pedro F. Saint-Maurice
  3. MRC Epidemiology Unit, School of Clinical Medicine, University of Cambridge, Cambridge, CB2 0QQ, UK
    Youngwon Kim
  4. School of Nutrition and Health Promotion, Arizona State University, 550 N Third St, Phoenix, AZ, 85004, USA
    Glenn A. Gaesser

Authors

  1. Pedro F. Saint-Maurice
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  2. Youngwon Kim
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  3. Gregory J. Welk
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  4. Glenn A. Gaesser
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Corresponding author

Correspondence toPedro F. Saint-Maurice.

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Conflict of interest

All the authors declare no conflicts of interest.

Additional information

Communicated by Jean-René Lacour.

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Saint-Maurice, P.F., Kim, Y., Welk, G.J. et al. Kids are not little adults: what MET threshold captures sedentary behavior in children?.Eur J Appl Physiol 116, 29–38 (2016). https://doi.org/10.1007/s00421-015-3238-1

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