The benefits gained from exercise-based cardiac rehabilitation programmes are evidence-based and widely recognized. 1,2 Furthermore, cardiac rehabilitation is a cost-effective therapy, proven to reduce premature cardiovascular and all-cause mortality and to improve health-related quality of life. 3 However, its implementation in clinical practice is still very poor. 4 In this focus issue of the journal, some of the controversial points related to clinical implementation of cardiac rehabilitation are discussed in original research studies. Focus on exercise training modalities Non-linear is not superior to linear aerobic training periodization in coronary heart disease patients The existing models of exercise prescription on cardiac rehabilitation focus mainly on aerobic exercises, with a progressive adaptation of the intensity and duration according to the patient's capacity and preference. 5 Traditional periodization, proposed in the guidelines for coronary artery disease (CAD) patients, also referred to as linear periodization, typically begins with low exercise intensity and short duration and focuses on a gradual increase in both of these parameters. However, linear periodization could potentially lead to fatigue and overreaching. To mitigate this risk, various forms of non-linear periodization (NLP), characterized by a more frequent manipulation of the training load, were used mainly in athletes. Here, Boidin et al. compared linear periodization versus NLP, blindly randomized, in a 12-week supervised exercise programme on the cardiopulmonary exercise response in patients with CAD. 6 All patients completed cardiopulmonary exercise testing (CPET): peak oxygen uptake (peak VO 2), O 2 uptake, efficiency slope, ventilatory efficiency slope, VO 2 at the first and second ventilatory thresholds, and oxygen pulse (O 2 pulse) were measured. In short, the authors showed that after three months of aerobic exercise training both protocols similarly improved peak VO 2 , peak ventilation, O 2 pulse and oxygen uptake efficiency slope. This finding confirmed that more variation (NLP), as suggested by some authors, is not necessary for greater cardiopulmonary and haemodynamic adaptations.