This paper describes the application of best practice recommendations for using accelerometers in a physical activity (PA) intervention trial, and the concordance of different methods for measuring PA. A subsample (n=63; 26%) of the 239 healthy, sedentary adults participating in a PA trial (mean age=47.5; 82% women) wore the ActiGraph monitor at all 3 assessment time points. ActiGraph data were compared with self-report (i.e., PA weekly recall and monthly log) and fitness variables. Correlations between the PA recall and ActiGraph for moderate intensity activity ranged from 0.16-0.48 and from 0.28-0.42 for vigorous intensity activity. ActiGraph and fitness [estimated VO2(ml/kg/min)] had correlations of 0.15-0.45. The ActiGraph and weekly self-report were significantly correlated at all time points (correlations ranged from 0.23 to 0.44). In terms of detecting intervention effects, intervention groups recorded more minutes of at least moderate-intensity PA on the ActiGraph than the control group at 6months (min=46.47, 95% CI=14.36-78.58), but not at 12months. Limitations of the study include a small sample size and only 3days of ActiGraph monitoring. To obtain optimal results with accelerometers in clinical trials, the authors recommend following best practice recommendations: detailed protocols for monitor use, calibration of monitors and validation of data quality, and use of validated equations for analysis. The ActiGraph has modest concordance with other assessment tools and is sensitive to change over time. However, until more information validating the use of accelerometry in clinical trials becomes available, properly administered self-report measures of PA should remain part of the assessment battery.
Bibliographical noteFunding Information:
The authors would like to acknowledge the contributions of Linda Christian, Robin Cram, Lisa Cronkite, Santina Horowitz, Maureen Hamel, Kenny McParlin, Hazel Ouellette, Yunxia Sui, Susan Pinheiro, Regina Traficante, and Kate Williams. The authors also would like to thank Chi Chan for her assistance in manuscript preparation. This research was supported by grant HL64342 to Dr. Marcus from the National Heart, Lung, and Blood Institute .
- Best practice recommendations
- Objective monitoring