A Preliminary Study to Determine Instrument Responsiveness to Change with a Walking Program: Physical Activity Logs versus Pedometers

Scientific review criteria for evaluating health status instruments, among them measures of physical activity, have been established (Lohr et al., 1996). In addition to reliability and validity, instruments that measure physical activity must be sensitive, or responsive, to longitudinal differences within individuals, as a result of intervention. Specifically,practitioners require measurement tools capable ofcapturing true changes in physical activity behaviors to evaluate their interventions. Few studies exist that examine responsiveness to change among the different approaches to physical activity measurement. Self-report methods (including diaries or logs and surveys or questionnaires) have been the preferred method of quantification to date, likely due to their perceived ease of administration, specifically their ability to collect data from a large number of people at a relatively low cost (Sallis & Saelens, 2000). Shortcomings ofany type ofself-reported data are widely known and include recall and social desirability biases. The accurate assessment of walking or ambulatory activity, regardless of purpose or context, is considered especially problematic (Ainsworth, Leon, Richardson.jacobs, & Paffenbarger, 1993; Kriska et al., 1990; Richardson, Leon.jacobs, Ainsworth, & Serfass, 1994). Ironically, ambulatory activity is also considered the most important activity to assess accurately (Tudor-Locke