Pulmonary rehabilitation in lung transplantation: Its effects on pulmonary function, physical fitness, and quality of life

Table 3 Physiological mechanism of functional improvements after pulmonary rehabilitation in lung transplantation recipients

Domain/output	Repair mechanism	Factors affecting the amount of improvement
Lung function	Progressive breathing exercises increase respiratory muscle strength and endurance, resulting in increased FEV1, FVC, faster extubation, optimal ventilation	ICU length of stay, transplant type, patient baseline condition, exercise intensity, and adherence
Cardiorespiratory fitness/exercise tolerance	Aerobic and HIIT training improves work capacity, oxygen efficiency, and participation in daily activities. It also leads to increased functional exercise tolerance	Compliance with exercise, achieved HIIT intensity, ventilatory capacity (FEV1, respiratory reserve), time to PR initiation (< 2 years post-LTx), sedentary behavior
Muscle fitness	High-intensity resistance training increases leg muscle strength, facilitating functional activity and exercise capacity. Training respiratory muscles reduces fatigue	Initial muscle weakness, duration of ICU stays, steroid/immunosuppressive use, type of exercise (resistance vs light), compliance
Activities and participation	Increased muscle strength and exercise capacity make daily activities easier to perform with relatively lower stress. Supervised exercise increases self-efficacy	Sedentary behavior, motivation level, outpatient rehabilitation support, exercise compliance
Quality of life	Increased physical capacity, participation, and social/psychological interaction during PR improves perceptions of physical and mental health	Duration and intensity of PR, duration of hospitalization, initial condition of the patient, ceiling effect on mental scores, compliance
Cardiovascular morbidity	Physical activity lowers blood pressure through acute reductions in vascular resistance and chronic adaptations of the autonomic nervous system. Exercise prevents hypertension and diabetes after LTx	Physical activity level, extreme sedentary behavior, post-transplant lifestyle

FEV1: Forced expiratory volume in one second; FVC: Forced vital capacity; HIIT: High-intensity interval training; PR: Pulmonary rehabilitation; LTx: Lung transplantation; ICU: Intensive care unit.