BackgroundStudies have widely investigated the effects of inspiratory muscle strength training in patients with heart failure (HF). The effects of inspiratory muscle strength or endurance training on outcomes in patients with pacemakers have not been adequately studied. ObjectivesThe aim was to compare the effects of inspiratory muscle strength and endurance training on exercise capacity, quality of life (QoL), peripheral and respiratory muscle strength, respiratory muscle endurance, pulmonary function, dyspnea, fatigue, and physical activity levels in pacemaker patients with HF. MethodsA randomized, controlled, double-blind study was conducted. Fourteen pacemaker patients with HF received inspiratory muscle strength training (IMST) at 50% of maximal inspiratory pressure (MIP), and 18 patients received endurance training (IMET) at 30% of MIP 7 days/8 weeks. Exercise capacity [6 min. walking test (6MWT) and the Incremental Shuttle Walking Test (ISWT)], pulmonary function, respiratory muscle strength [MIP, maximal expiratory pressure (MEP)], endurance, peripheral muscle strength, dyspnea, fatigue, QoL, and physical activity level were evaluated before and after. ResultsDemographic characteristics were similar in IMST (3F/11M, 56.92 ± 7.61y, EF: 25%, ICD/CRT:11/3) and IMET (4F/14M, 56 ± 10.77y, EF: 30%, ICD/CRT:16/2) groups (p > 0.05). Significant improvements were present in MIP, MEP, respiratory muscle endurance, peripheral muscle strength, 6MWT and ISWT walking distances, dyspnea, QoL, physical activity level, fatigue scores within groups (p ≤ 0.05). However, there were no significant differences between the groups (p > 0.05). There were no significant improvements in FEV1%, FVC%, FEV1/FVC%, and FEF25-75 within and between the groups (p > 0.05). ConclusionsInspiratory muscle strength and endurance training similarly improves respiratory and peripheral muscle strength, exercise capacity, QoL, physical activity level, and decreases dyspnea and fatigue and are safe and effective in pacemaker patients with HF. Trial registrationwww.ClinicalTrials.gov; study number: NCT03501355.