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  • Author: J. Michael Oakes x
  • Psychology and Behavior in Sport/Exercise x
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Ann Forsyth, J. Michael Oakes and Kathryn H. Schmitz

Background:

The Twin Cities Walking Study measured the associations of built environment versus socioeconomic and psychosocial variables with total physical activity and walking for 716 adults.

Methods:

This article reports on the test–retest reliability of the survey portion of the study. To test the reliability of the study measures, 158 respondents completed measures twice within 1 to 4 weeks. Agreement between participants’ responses was measured using Pearson r and Spearman rho, and kappa statistics.

Results:

Demographic questions are highly reliable (R > .8). Questions about environmental and social features are typically less reliable (rho range = 0.42– 0.91). Reliability of the International Physical Activity Questionnaire (last 7 days version) was low (rho = 0.15 for total activity).

Conclusions:

Much of the survey has acceptable-to-good reliability. The low test–retest reliability points to potential limitations of using a single administration of the IPAQ to characterize habitual physical activity. Implications for sound inference are accordingly complicated.

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John R. Sirard, Ann Forsyth, J. Michael Oakes and Kathryn H. Schmitz

Background:

The purpose of this study was to determine 1) the test-retest reliability of adult accelerometer-measured physical activity, and 2) how data processing decisions affect physical activity levels and test-retest reliability.

Methods:

143 people wore the ActiGraph accelerometer for 2 7-day periods, 1 to 4 weeks apart. Five algorithms, varying nonwear criteria (20 vs. 60 min of 0 counts) and minimum wear requirements (6 vs. 10 hrs/day for ≥ 4 days) and a separate algorithm requiring ≥ 3 counts per min and ≥ 2 hours per day, were used to process the accelerometer data.

Results:

Processing the accelerometer data with different algorithms resulted in different levels of counts per day, sedentary, and moderate-to-vigorous physical activity. Reliability correlations were very good to excellent (ICC = 0.70−0.90) for almost all algorithms and there were no significant differences between physical activity measures at Time 1 and Time 2.

Conclusions:

This paper presents the first assessment of test-retest reliability of the Actigraph over separate administrations in free-living subjects. The ActiGraph was highly reliable in measuring activity over a 7-day period in natural settings but data were sensitive to the algorithms used to process them.