Criterion and concurrent validity of the activPAL™ professional physical activity monitor in adolescent females

PLoS One. 2012;7(10):e47633. doi: 10.1371/journal.pone.0047633. Epub 2012 Oct 19.


Background: The activPAL has been identified as an accurate and reliable measure of sedentary behaviour. However, only limited information is available on the accuracy of the activPAL activity count function as a measure of physical activity, while no unit calibration of the activPAL has been completed to date. This study aimed to investigate the criterion validity of the activPAL, examine the concurrent validity of the activPAL, and perform and validate a value calibration of the activPAL in an adolescent female population. The performance of the activPAL in estimating posture was also compared with sedentary thresholds used with the ActiGraph accelerometer.

Methodologies: Thirty adolescent females (15 developmental; 15 cross-validation) aged 15-18 years performed 5 activities while wearing the activPAL, ActiGraph GT3X, and the Cosmed K4B2. A random coefficient statistics model examined the relationship between metabolic equivalent (MET) values and activPAL counts. Receiver operating characteristic analysis was used to determine activity thresholds and for cross-validation. The random coefficient statistics model showed a concordance correlation coefficient of 0.93 (standard error of the estimate = 1.13). An optimal moderate threshold of 2997 was determined using mixed regression, while an optimal vigorous threshold of 8229 was determined using receiver operating statistics. The activPAL count function demonstrated very high concurrent validity (r = 0.96, p<0.01) with the ActiGraph count function. Levels of agreement for sitting, standing, and stepping between direct observation and the activPAL and ActiGraph were 100%, 98.1%, 99.2% and 100%, 0%, 100%, respectively.

Conclusions: These findings suggest that the activPAL is a valid, objective measurement tool that can be used for both the measurement of physical activity and sedentary behaviours in an adolescent female population.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Calibration
  • Female
  • Humans
  • Metabolic Equivalent / physiology*
  • Monitoring, Ambulatory / instrumentation*
  • Monitoring, Ambulatory / methods*
  • Motor Activity / physiology*
  • Posture / physiology
  • ROC Curve
  • Sedentary Behavior

Grant support

KD is supported by a studentship from the Irish Research Council for Science, Engineering and Technology (IRCSET), Shelbourne Rd., Dublin 4, Ireland. These funders had no role in the study design, collection, analysis and interpretation of the data, in the writing of the article and in the decision to submit the paper for publication.