Medical, demographic and social cognitive correlates of physical activity in a population-based sample of colorectal cancer survivors.

Physical activity (PA) improves quality of life in colorectal cancer survivors (CRC) and may reduce the risk of disease recurrence and early death. Few studies, however, have examined the correlates of PA in CRC survivors. Using the Alberta Cancer Registry, 2000 randomly selected CRC survivors were mailed a self-reported questionnaire assessing medical, demographic, behavioural and social cognitive variables from the theory of planned behaviour (TPB). Of the 600 survivors who responded, 33% were meeting public health PA guidelines and almost half were completely sedentary. Higher PA was reported by survivors who were younger, unmarried, better educated, wealthier, employed, non-smokers, social drinkers, not treated with radiation therapy, disease-free, in better health and less comorbidity. In multivariate path analysis, these variables were not directly associated with PA after controlling for the TPB variables. The TPB explained 34% (P < 0.001) of the variance in PA behaviour with direct associations for intention (β= 0.22; P= 0.015) and planning (β= 0.18; P= 0.001). Intention, in turn, had 62% (P < 0.001) of its variance explained by perceived behavioural control (β= 0.43; P < 0.001), affective attitude (β= 0.25; P < 0.001) and instrumental attitude (β= 0.15; P < 0.001). The TPB may be a useful framework for developing population-based interventions to increase PA in CRC survivors.