Physical activity among adults with obesity: Testing the health action process approach.

OBJECTIVE: This study tested the applicability of the Health Action Process Approach (HAPA) in a sample of obese adults in the context of physical activity. METHOD: Physical activity was assessed along with motivational and volitional variables specified in the HAPA (motivational self-efficacy, outcome expectancies, risk perception, intention, maintenance self-efficacy, action planning, coping planning, recovery self-efficacy, social support) in a sample of 484 obese men and women (body mass index ≥ 30 kg/m2). RESULTS: Applying structural equation modeling, the fit of the HAPA model was satisfactory-χ²(191) = 569.93, p < .05, χ²/df = 2.98, comparative fit index = .91, normed-fit index = .87, and root mean square error of approximation = .06 (90% CI = .06, .07)-explaining 30% of the variance in intention and 18% of the variance in physical activity. Motivational self-efficacy, outcome expectancies, and social support were related to intention. An association between maintenance self-efficacy and coping planning was found. Recovery self-efficacy and social support were associated with physical activity. No relationships were found between risk perception and intention and between planning and physical activity. The assumptions derived from the HAPA were partly confirmed and the HAPA may, therefore, constitute a theoretical backdrop for intervention designs to promote physical activity in adults with obesity.