In this Commentary, we aim to discuss a paper by Nasis et al. recently published in this journal (Nasis et al., 2015). As a basis for our comment, we would like to begin with a presentation of some background information of the topic of the relationship between cardiac and pulmonary variables during exercise. Cardio-pulmonary interactions can be difficult to explore in healthy and in COPD patients, especially during exercise. One method allowing access to these interactions is the examination of the ventilatory, pulmonary gas exchange, and heart rate kinetics response to high-intensity exercise.