Affective Response to Physical Activity: Testing for Measurement Invariance of the Physical Activity Affect Scale Across Active and Non-Active Individuals

Affective responses to physical activity are assumed to play a role in exercise initiation and maintenance. The Physical Activity Affect Scale measures four dimensions of an individual's affective response to exercise. Group differences in the interpretation of scale items can impact the interpretability of mean differences, underscoring the need to examine whether measurement structure holds across groups (e.g., active vs. non-active). In the current study, physically active (n = 158) and non-active (n = 179) participants exercised for 30 min; affect was assessed during exercise (i.e., 20 min). Tests of measurement invariance were conducted in a confirmatory factor analytic framework. There was good evidence for measurement invariance of the Physical Activity Affect Scale across active and non-active groups, with a single non-invariant factor loading, invariance in item intercepts, and invariance in item uniquenesses, although patterns of factor covariances and means differed across groups. Recommendations and implications of research are provided. Key words: affectexercisephysical activity affect scalemeasurement invariancein-task response Notes 1It was impossible to directly test the measurement invariance of the loadings and intercepts of the marker variables. Instead, a series of models were, in fact, estimated, where the specific marker variables used were allowed to differ across models. The final marker variables were chosen in part because the factor loadings and intercepts of these four variables were found to be consistently invariant across groups.