Nicholas Barefoot, Battogtokh Zagdsuren, Mark Richardson, Hayley MacDonald. The University of Alabama, Tuscaloosa, AL.

BACKGROUND: This study is part of a larger project examining the interaction between automatic and reflective processes in relation to PA behavior. Central to the dual-process theory is the concept of effort mobilization, or the amount of resources individuals mobilize to execute behavior. Greater effort may be required when there is conflict between behavioral automaticity and the goal or task being pursued. Cardiovascular (CV) responses to cognitive challenge, CV reactivity, are objective and reliable measures of effort mobilization but have yet to be evaluated during the automatic evaluation of PA behavior. PURPOSE: To explore the relationships among CV reactivity, automatic and reflective measures of PA behavior, and individual characteristics that influence these processes. METHODS: This pilot study includes 15 subjects from a larger project (47% women, age: 21±3 y, body mass index: 25.6±4.1 kg/m2). A computerized Single Category Implicit Association Test (SCIAT) measured implicit attitudes towards PA behaviors (positive scores indicated positive affect toward the target behavior). HR and MAP were measured using a finger cuff during SCIAT assessments. Averages obtained during the test and change scores (expressed as a percentage of change from rest) were used to quantify CV reactivity. Habitual PA (min/d) was measured with an accelerometer. Reflective PA measures (e.g., intention, enjoyment) were collected via questionnaire. Bivariate correlations examined relationships among study variables (α=0.05). RESULTS: MAP during the test correlated with light PA SCIAT scores (r=-0.52, p=0.05). MAP change scores correlated with sedentary behavior SCIAT scores (r=0.59, p=0.02) and intention to perform exercise (r=-0.61, p=0.02). HR during the test correlated with intention to perform exercise (r=-0.75, p<0.01) and PA enjoyment (r=-0.70, p<0.01). CONCLUSIONS: Lower CV reactivity during the SCIAT was related to positive affect toward PA behavior and greater PA intention, suggesting that these subjects found PA stimuli to be less stressful (required less effort). Conversely, higher CV reactivity was related to negative affect of PA and positive affect of sedentary behavior, suggesting that both PA and sedentary stimuli were more stressful (required greater effort). By focusing efforts on these perceptions, future PA guidelines may be more successful in increasing PA levels and decreasing sedentary behavior.

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