Exercise-based cardiac rehabilitation (CR) has been shown to consistently reduce the rates of total and cardiovascular-related mortality and morbidity. Sedentary behaviours have been shown to be high in patients with cardiovascular disease, but it is not yet known if current CR programming results in significant reductions in these behaviours, or whether a targeted component is warranted. It is also unclear if self-reported sedentary time measures can provide valid and reliable information for monitoring these behaviours in a CR setting, or whether more objective measures are needed. The purpose of this study is to assess the feasibility and usability of the activPAL3 devices for measuring sedentary time in a CR setting, describe changes in sedentary time that occur with standard CR and assess whether the addition of prompting cues from a device can result in further declines in sedentary behaviour and improvements in clinical outcomes, health related quality of life, symptoms of anxiety and depression, aortic stiffness, and aerobic capacity.