Initial Validation of the Activity Choice Index Among Overweight Women Sean P. Mullen , 1 Marlene N. Silva, 2,3 Luís B. Sardinha, 2 and Pedro J. Teixeira 2 1 University of Illinois at Urbana-Champaign; 2 University of Lisbon; 3 Lusophone University of Humanities and Technologies ABSTRACT Purpose: This prospective study was designed to evaluate psychometric properties of the Activity Choice Index (ACI), a measure for assessing one’s choice to engage in more effortful, physically active behaviors in the course of daily routines over less-demanding, sedentary behaviors, in a sample of overweight women. Method: The sample included 192 overweight women (M age ¼ 37.6 ^ 7 years; M body mass index ¼ 31.6 ^ 4.1 kg/m 2 ) who were assessed at baseline and 12 months after beginning a weight management intervention. Results: The unidimensional factor structure was confirmed for the 6-item version of the ACI. Group invariance and temporal invariance were also established. Moreover, ACI scores were positively correlated with self-reported physical activity (as measured by the 7-Day Physical Activity Recall), daily pedometer steps, and 3-day average accelerometer counts. Conclusions: This preliminary investigation provides evidence that a relatively brief self-report instrument for assessing lifestyle physical activity choices has strong psychometric characteristics although convergent evidence is limited. The ACI has potential utility for researchers and practitioners aiming to quantify, or track change in, physical activity in everyday, free-living conditions. This early investigation sets the stage for future research to further delineate and strengthen the measurement of the ACI construct. ARTICLE HISTORY Received 30 May 2014 Accepted 27 November 2015 KEYWORDS Accelerometry; measure- ment; physical activity; physical activity assessment It is well-recognized that adult levels of physical activity engagement are low, and it is a widespread international problem (Bauman et al., 2009). There is also strong evidence that sedentary behavior is independently associated with health status (Katzmarzyk, Church, Craig, & Bouchard, 2009) and that engagement in daily-life physical activities such as cycling to work are inversely associated with obesity (Wen & Rissel, 2008). Thus, it is becoming more important to quantify the extent to which adults make physical activity choices throughout the day. Current global physical activity recommendations for overall health among healthy adults aged 18 to 64 years include 2 hr and 30 min (150 min) of moderate-intensity aerobic activities (i.e., brisk walking) every week and muscle-strengthening activities on 2 or more days per week (Bull & the Expert Working Groups, 2010; Haskell et al., 2007; World Health Organization, 2010). It is also recommended that adults engage in aerobic activity for bouts of at least 10 min in duration. Further recommendations from researchers have focused on the optimal minimal threshold for total number of daily steps (Tudor-Locke et al., 2011) and on recommendations to avoid long periods of sitting and other sedentary behaviors (Department of Health, Physical Activity, Health Improvement and Protection, 2011). Apparently “lost” in physical activity recommendations is a class of active behaviors that may only reach levels of moderate or vigorous intensity for brief periods of time and may be shorter than 10 min in duration. Examples are choosing to stand instead of sitting (e.g., while waiting in a line or attending a lecture), taking the stairs instead of the elevator/escalator whenever possible, and purposely parking farther away from entrances or leaving a public transport one station earlier/later than the closest station to the destination. Although they have not been differentiated within current physical activity recommen- dations, increased engagement in this class of behaviors has the potential to contribute to health and well-being via mobilization of large muscle groups and increased daily energy expenditure. More broadly, they may be a behavioral marker for a general disposition or attitude toward being physically active in an opportunistic fashion. Researchers have made various attempts to assess adult lifestyle activity, but no measures, to our knowl- edge, target self-selection of active over inactive lifestyle choices. Salmon, Owen, Crawford, Bauman, and Sallis (2003) developed a measure of “preference” for vigorous q 2016 SHAPE America CONTACT Sean P. Mullen spmullen@illinois.edu Department of Kinesiology and Community Health, University of Illinois at Urbana-Champaign, 227 Freer Hall, 906 S. Goodwin Avenue, Urbana, IL 61801. RESEARCH QUARTERLY FOR EXERCISE AND SPORT http://dx.doi.org/10.1080/02701367.2016.1152349 Downloaded by [b-on: Biblioteca do conhecimento online UL] at 01:57 31 March 2016