K. G. Jebsen from Center of Exercise in Medicine at the Norwegian University of Science and Technology (NTNU) in Trondheim, Norway, analyzed data from four randomized, controlled trials conducted at the centre to try to determine what characterized the most effective high-intensity training programme for this patient group.
The researchers used changes in VO2max, which is peak oxygen uptake, as a measure of the effectiveness of the different exercise regimes
The exercise period lasted for 12 weeks. The participants ran or walked on treadmill, walked uphill outdoors or trained in a group, all following the 4x4 exercise model. The 4x4 exercise model involves 4 minutes of high-intensity exercise followed by 3 minutes of moderate-intensity exercise, repeated 4 times.
Lead author of the study, Trine Moholdt, said that when they compared VO2max before and after the training period, they found that the number of training sessions, the subject's age or baseline fitness levels had no impact, however the intensity of the intervals had a significant effect, and seemed to be the most important characteristic of an effective interval session.
The four studies, which were composed of patients who either had acute coronary syndrome or angina pectoris, confirmed previous findings that high-intensity exercise is safe, even for patients with CHD.