Eccentric muscle work is defined as lengthening of a muscle while applying force. It was shown that with eccentric work, muscles are able to perform four times as much power compared to usual concentric work, which results in huge training gain with a highly decreased oxygen demand and thus lower cardiovascular load. Pulmonary hypertension (PH) is a chronic condition associated with significant reduced exercise capacity and increased morbidity and mortality, resulting in reduced quality of life. Physical training has been shown to be beneficial in PH, even in severely limited patients. However, due to cardiopulmonary constraints in PH, training intensities may be very low, so that many patients are physically almost unable to perform exercise on a high enough level to maintain muscle mass. A low body muscle not only feeds the vicious cycle of decreasing exercise capacity, but also has many deleterious metabolic and immunological consequences which further increase disability and decrease quality of life in PH. Thus, eccentric training, which allows to gain muscle mass with a low stress to the cardiopulmonary unit may to be highly beneficial for patients with PH and allied cardiopulmonary disease, such as chronic obstructive pulmonary disease (COPD) and heart failure. Therefore, the objective of the trial is, to compare differences in oxygen uptake (peak VO2 \[l/min\]) and other physiological measures during similar cardiopulmonary exercise test protocols of eccentric- vs. concentric cycling in PH- patients and comparators with or without other cardiopulmonary diseases.