Effectiveness of Eccentric Cycling Exercise in Ambulatory Rehabilitation for Patients With Cardiopulmonary Diseases: A Pragmatic Randomized Controlled Trial

In eccentric cycling exercise (ECC), the cyclist must oppose backwards moving pedals on a specialized motor-driven ergometer. Throughout this process, the force applied on the pedals exceeds the torque generated by the lengthening muscle (negative work), concurrently generating and storing elastic recoil energy. During ECC the cyclist is able to reach fourfold higher forces compared to conventional concentric cycling exercise (CON) . At identical work-rates however, ECC is associated with a lower cardiac output 5 and requires up to 80% less oxygen uptake 6 than CON. Hence, ECC is described as a promising and efficient exercise method with low metabolic costs. Some studies suggests that ECC may exhibit greater effectiveness compared to CON, especially in terms of increasing muscle strength, muscle hypertrophy, six-minute walk distance (6MWD).

A loss in muscle mass and sarcopenia is present also in the non-diseased population and is increasing with age. A yearly loss of muscle mass in the general population is around 1% at the age of 40 and increases to 2% at the age of 70. This loss in muscle mass can be accelerated in patients with chronic cardiopulmonary diseases and especially in patients with lung cancer undergoing systemic therapies, mainly as chemotherapy.

A recent systematic review with meta-analysis, including studies with a total of 867 patients with lung cancer, conclusively demonstrated that patients undergoing chemotherapy are at risk for a marked loss of skeletal muscle mass and sarcopenia.14 Another study found in around 50% of their lung cancer patients receiving chemotherapy a significant reduction in muscle cross sectional area.15 Sarcopenia has a high burden of disease and has been found to be associated with significant lower survival in patients, as well as with a range of negative outcomes including disability, frailty, morbidity, and reduced quality of life. To prevent sarcopenia patients with cardiopulmonary disease, and patients undergoing chemotherapy should perform regular exercise training. Supervised exercise training and three months of rehabilitation have been shown to be effective, safe and well-tolerated in patients with chronic cardiopulmonary or pulmonary vascular disease. Therefore, a three-month ambulatory rehabilitation program provides a reliable option for these patients to exercise regularly in a supervised setting.

However, patients with advanced cardiopulmonary diseases, such as chronic obstructive pulmonary disease, heart failure, pulmonary hypertension, interstitial lung disease, or advanced stage lung cancer, often suffer from exercise intolerance. In patients whose cardiopulmonary limitations are so severe that they cannot even reach beneficial exercise intensities, the value of an ambulatory rehabilitation program needs to be carefully considered.

Nevertheless, with the features of ECC, even these patients are able to exercise at beneficial levels while maintaining a low metabolic demand. Previous studies have shown that ECC can be effective, even at low intensities, in patients with chronic cardiopulmonary conditions such as pulmonary hypertension or chronic obstructive pulmonary disease. Interestingly, patients additionally reported less perceived dyspnea with unchanged leg fatigue. Furthermore, ECC was associated with reduced pulmonary arterial pressure and improved right ventricular function.