Reliability of moderate-intensity and vigorous physical activity stage of change measures for young adults.

<b>Background</b><br />The purpose of this study was to examine the reliability of stage of change (SOC) measures for moderate-intensity and vigorous physical activity in two separate samples of young adults. Staging measures have focused on vigorous exercise, but current public health guidelines emphasize moderate-intensity activity.<br /><b>Method</b><br />For college students in the USA (n = 105) and in Australia (n = 123), SOC was assessed separately on two occasions for moderate-intensity activity and for vigorous activity. Test–retest repeatability was determined, using Cohen’s kappa coefficient.<br /><b>Results</b><br />In both samples, the reliability scores for the moderate-intensity physical activity staging measure were lower than the scores for the vigorous exercise staging measure. Weighted kappa values for the moderate-intensity staging measure were in the “fair to good” range for both studies (0.50 and 0.45); for the vigorous staging measure kappa values were “excellent” and “fair to good” (0.76 and 0.72).<br /><b>Conclusions</b><br />There is a need to standardize and improve methods for staging moderate-intensity activity, given that such measures are used in public health interventions targeting HEPA (health-enhancing physical activity).<br />