Exercise training procedure
All children with CHD were postoperatively admitted to the intensive care unit. Within 24 h of being transferred from the intensive care unit to the general ward, the exercise group received exercise therapy based on the routine nursing treatment of the control group. The bedside power bicycle 30-min intervention program, which included 5 min of warm-up, 20 min of exercise therapy, and 5 min of recovery, was added to their treatment. The target heart rate during exercise was 20–30% higher than the basal heart rate (once per day). Breath-holding was avoided during the intervention process, and effective diaphragmatic breathing was incorporated. Cardiovascular specialists and rehabilitation therapists monitored and recorded the exercise process to ensure the safety of the participants.