Background: A crucial part of rehabilitation of cardiovascular disease is to increase aerobic capacity. High intensity intervals are an emerging field in cardiac rehabilitation. Adhering to physical training has been shown to be quite hard for these patients. There is no systematic review of different training intensities for these patients that also include interventions towards changing and adhering to new training behaviors. Objective: Map out changes in VO2peak from high intensity intervals or moderate continuous training in cardiac rehabilitation and to see if theories or techniques for behavioral change was applied to maintain and increase adherence to physical activity. Method: This systematic review was done with the databases of PubMed and PEDro. The studies could only include patients with heart failure or coronary artery diseases. Articles were assessed for quality and given a preliminary level of evidence. Results: 11 articles were included; ten studies showed a significant increase in VO2peak. Three studies showed a significant increase in VO2peak between groups in favor of high intensity intervals. Some behavior change techniques could be interpreted by the authors, but no theories were used. Conclusion: This review could not conclude that one specific modality of training is superior in cardiac rehabilitation.