## 4 Discussion
### Effects of Various Exercise Moderators on QOL in HF Patients  
Declines in cardiopulmonary function and muscle strength limit HF patients' daily activities. Combined aerobic and resistance exercise significantly improves aerobic capacity and MLHFQ scores in HF patients [119], and combined exercise leads to more significant improvements in submaximal exercise capacity, muscle strength, and QOL compared to aerobic exercise alone [120]. Combined exercise effectively improves muscle strength and provides similar aerobic capacity benefits as aerobic exercise alone, which is significant for alleviating muscle strength intolerance in daily life and improving QOL. Our subgroup analysis showed that exercise sessions lasting 60 min or more significantly improved QOL in HF patients, which is consistent with previous studies. A 12-week Tai Chi program with 60 min sessions improved MLHFQ scores and self-efficacy in patients with CHF [121], and long-duration (90-120 min) combined exercise significantly improved aerobic capacity, muscle strength, and reduced MLHFQ scores [122]. Prolonged light cycling exercise increased brain-derived neurotrophic factor (BDNF) levels and cognitive memory function [123], which is significant for HF patients' prognosis. However, excessively long exercise sessions may cause injuries and diminish positive effects [124; 125], while too short sessions may fail to achieve desired effects [126]. Future research should explore safe and effective exercise durations for HF patients. Interventions performed at least three times per week significantly improved QOL in patients. A walking intervention performed three times per week improves exercise capacity, sleep duration, and reduces MLHFQ scores in elderly women with HFpEF [127], and a 9-week remotely supervised training program performed five times per week sig nificantly improved VO2 peak and Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) scores in HF patients [128]. Regular and frequent exercise promotes a positive mindset and enhances self-management abilities. However, in practical applications, exercise performed less than three times per week may also yield some improvement effects, and its potential benefits remain worthy of attention. The subgroup analysis results were similar to those for aerobic capacity, showing that both weekly times of less than 180 min and those of 180 min or more significantly improved QOL in HF patients. Specifically, exercise programs with a weekly time of 180 min or more demonstrated better improvement effects. Consistent with previous findings, [PERSON] et al. [129] reported that a 180 min weekly combined exercise program significantly improved VO2 peak and muscle strength in HFpEF patients. An expert consensus recommendation supports our findings, suggesting that HF patients gradually increase exercise frequency and duration to achieve a weekly goal of 300 min, thereby enhancing physical capacity and QOL [130]. Considering the target of 180 min or more of weekly exercise, this can be achieved by either increasing frequency or extending the session duration. However, for HF patients, taking into account safety and tolerance, increasing frequency may be a safer and more feasible option. We conducted a subgroup analysis on whether the implementation of exercise programs was supervised by healthcare professionals. The results showed that supervised exercise led to better improvements in aerobic capacity and QOL in HF patients, which is consistent with a previous study [131], showing that outpatient-based supervised exercise programs significantly improved aerobic capacity and QOL in HFrEF patients. Additionally, [PERSON] et al. [132] reported that 12 weeks of supervised exercise significantly improved VO2 peak in HF patients, but this effect was not further enhanced during subsequent home-based exercise. The study also noted that patient adherence was higher in supervised settings, whereas adherence was suboptimal in self-supervised environments.