Background: Heart failure (HF) is one of the major causes of mortality worldwide, representing the terminal stage of several cardiovascular diseases. Exercise-based rehabilitation is a beneficial therapy for patients with chronic heart failure (CHF). However, there is a lack of specific guidance on clinical decision-making regarding optimal exercise intensity. It is necessary to optimize the clinical recommendations for HF exercises. We will evaluate the efficacy and safety of different aerobic exercise intensities in patients with heart failure with reduced ejection fraction (HFrEF): the HF-EI trial. This trial aims to assess the appropriate exercise intensity for patients with HFrEF. Methods: After a baseline assessment to determine the safety of exercise, 180 patients will be randomly assigned to supervised high-intensity exercise training (ET) group, supervised moderate intensity training (MIT) group, and control group at a ratio of 1:1:1. Patients randomly receiving high intensity training (HIT) undergo supervised ET (3 times/week, 30 min) for aerobic endurance at 70% peak oxygen consumption (peak VO2) intensity for 12 weeks. The MIT patients will perform supervised aerobic ET (3 times/week, 35-42 min) at the anaerobic threshold (AT) intensity for 12 weeks. The control group will continue to maintain their daily activities and will not receive ET. During the baseline and follow-up period, physical examination, laboratory tests, cardiology diagnostic tests, cardiopulmonary exercise tests (CPET), 6-min walk distance (6MWD), scale scores, exercise steps, medications, and clinical events will be monitored. Throughout the research, sport bracelets and patient diaries will be used to monitor and record overall physical activity, training courses, and compliance. Discussion: The HF-EI trial will evaluate the effects of different aerobic exercise intensities on peak VO2, quality of life (QoL), and clinical events among patients with HFrEF. The findings of this trial will provide a basis for formulating exercise prescriptions for patients with HFrEF. Clinical Trial Registration:http://www.chictr.org.cn/, identifier: ChiCTR2000036381.

中文翻译：

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射血分数降低的心力衰竭患者不同有氧运动强度的有效性和安全性：多中心随机对照试验（HF-EI 试验）的设计。

背景：心力衰竭 (HF) 是全球死亡的主要原因之一，代表了几种心血管疾病的终末阶段。基于运动的康复是慢性心力衰竭 (CHF) 患者的有益疗法。然而，关于最佳运动强度的临床决策缺乏具体指导。有必要优化 HF 练习的临床建议。我们将评估不同有氧运动强度对射血分数降低 (HFrEF) 心力衰竭患者的疗效和安全性：HF-EI 试验。该试验旨在评估 HFrEF 患者的适当运动强度。方法：在确定运动安全性的基线评估后，180名患者将按1:1:1的比例随机分配到有监督的高强度运动训练（ET）组、有监督的中等强度训练（MIT）组和对照组。随机接受高强度训练 (HIT) 的患者在 70% 峰值耗氧量（峰值 VO2）强度下进行 ET（3 次/周，30 分钟）的有氧耐力训练，持续 12 周。麻省理工学院患者将在无氧阈值 (AT) 强度下进行 12 周的监督有氧 ET（3 次/周，35-42 分钟）。对照组将继续维持日常活动，不会接受ET。在基线和随访期间，体格检查、实验室检查、心脏病学诊断检查、心肺运动试验 (CPET)、6 分钟步行距离 (6MWD)、量表评分、运动步数、药物、和临床事件将被监测。在整个研究过程中，运动手环和患者日记将用于监测和记录整体身体活动、培训课程和依从性。讨论：HF-EI 试验将评估不同有氧运动强度对 HFrEF 患者的峰值 VO2、生活质量 (QoL) 和临床事件的影响。该试验的结果将为制定 HFrEF 患者的运动处方提供基础。临床试验注册：http://www.chictr.org.cn/，标识符：ChiCTR2000036381。HFrEF 患者的生活质量 (QoL) 和临床事件。该试验的结果将为制定 HFrEF 患者的运动处方提供基础。临床试验注册：http://www.chictr.org.cn/，标识符：ChiCTR2000036381。HFrEF 患者的生活质量 (QoL) 和临床事件。该试验的结果将为制定 HFrEF 患者的运动处方提供基础。临床试验注册：http://www.chictr.org.cn/，标识符：ChiCTR2000036381。