Abstract
The majority of women treated for breast cancer are physically inactive although physical activity (PA) could attenuate many adverse effects of cancer and treatment. Autonomy support from healthcare professionals may improve PA initiation, adherence and maintenance. This study aimed to determine, using a causal inference approach, whether or not perceived autonomy support (PAS) from healthcare professionals is associated with light, moderate, and vigorous intensity PA among women treated for breast cancer. Data were drawn from the longitudinal study "Life After Breast Cancer: Moving On" (n = 199). PAS was measured with the Health Care Climate Questionnaire and PA was assessed using GT3X triaxial accelerometers. Associations between PAS and PA were estimated with linear regressions and adjusted estimations were obtained using propensity score-based inverse probability of treatment weights (IPTW). Results reveal no association between PAS and PA of light ([Formula: see text](95%CI) = -0.09 (-0.68, 0.49)), moderate ([Formula: see text] (95%CI) = -0.03 (-0.17, 0.11)), or vigorous ([Formula: see text](95%CI) = 0.00 (-0.03, 0.02)) intensity. Different forms of engagement and support by healthcare professionals should be explored to identify the best intervention targets to encourage women to adopt and maintain regular PA in the cancer continuum.