The aims of this work were to (i) provide level 1 published evidence of non-uniform trends in outcome measures related to exercise training in patients with cardiovascular disease, (ii) provide possible explanations for the non-uniform improvements observed and (iii) make recommendations to improve desired exercise training outcomes in people with cardiovascular disease. Meta-analyses and landmark randomized, controlled trials of exercise training in people with, or at risk of, cardiovascular disease (CVD), with at least 2 post-intervention time points, were identified so changes in effects sizes could be compared. With the exception of patients with peripheral vascular disease, the data appear to suggest that exercise training programs >12 weeks appear to produce smaller improvements in a variety of outcome measures, when compared to exercise training programs <12 weeks. Several factors may explain why CVD patients do not continue to improve their fitness after exercise training beyond 12 weeks. We make recommendations for periodization (rest or active recovery) to be incorporated to exercise programming in an attempt to reduce illness related withdrawal from exercise training.