Evaluating the efficacy of dual-task training in older patients with chronic heart failure and comorbid cognitive frailty: a protocol for a randomized controlled trial

Abstract

Background

Chronic heart failure (CHF) represents the severe manifestation or end stage of various cardiac diseases, characterized by high morbidity, readmission rates, and mortality. With the intensification of global population aging, the prevalence of CHF has risen significantly among the older population, becoming a major issue affecting seniors' health and quality of life. Aging not only increases CHF prevalence but also exacerbates its complexity and treatment difficulty. Recent studies indicate that CHF patients exhibit cognitive frailty, which significantly elevates their risks of readmission, diminished quality of life, and mortality. However, there is currently a lack of intervention strategies specifically targeting CHF patients with cognitive frailty. This study aims to investigate the comprehensive intervention effects of dual-task training on cognitive function, frailty phenotype, and quality of life in older patients with CHF through standardized randomized controlled trials, providing new pathways for optimizing geriatric comorbidity management.

Methods

This is a single-center, randomized controlled, single-blind clinical trial aiming to recruit 72 older patients with cognitive frailty and CHF hospitalized in the cardiology department. Participants will be randomly assigned in a 1:1 ratio to either the intervention group or the control group. Those in the intervention group will receive the progressive dual-task training intervention, while those in the control group will receive routine care. Participants in the intervention group will undergo this dual-task training three times per week for a period of three months. The primary outcome measures are cognitive function and physical frailty, while the secondary outcomes include exercise endurance, lower limb muscle strength, grip strength, and quality of life.

Discussion

This randomized controlled clinical trial will evaluate whether dual-task training improves cognitive function, frailty status, cardiac function, and quality of life in older patients with CHF and cognitive frailty. The results will provide further research evidence for clinical application in this population.

Trial registration

ClinicalTrials.gov identifier: ChiCTR2500105453, Registered July 3, 2025.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-026-06987-w.

Chronic heart failure (CHF) is a clinical syndrome characterized by impaired cardiac pumping function, representing the terminal stage of various cardiovascular diseases [1]. Recent epidemiological data indicate that over 64 million individuals worldwide are affected by heart failure [2], with approximately 8.9 million heart failure patients in China [3], establishing it as a major public health challenge. Concurrent with accelerated population aging, increasing attention is being directed toward frailty—a prevalent comorbid condition among older patients with CHF. According to international consensus, frailty is defined as a clinical state characterized by heightened vulnerability and impaired stress resistance resulting from diminished physiological reserves [4]. This condition is strongly associated with elevated readmission rates, deteriorating functional status, and increased all-cause mortality in CHF patients [5, 6].

The detrimental impact of CHF on cognitive function has been extensively validated. Since the introduction of the concept of “cardiogenic dementia” in 1977 [7], research has established that CHF induces cerebral dysfunction through multiple pathological mechanisms, including cerebral hypoperfusion, neurohormonal activation, and systemic inflammation [8, 9], resulting in a more than fourfold elevated risk of cognitive impairment relative to the general population [10]. Notably, cognitive impairment demonstrates a significant positive correlation with heart failure severity: Clinical data indicate that approximately 46% of CHF patients exhibit varying degrees of cognitive impairment [10], with both prevalence and severity increasing progressively as cardiac function deteriorates [11]. Robust evidence from a systematic review encompassing 4,176 CHF patients further confirms an overall risk of cognitive impairment 1.67-fold higher than in non-heart failure populations, coupled with a prevalence rate of approximately 43% [12]. Crucially, cognitive function is essential for managing the numerous self-care activities fundamental to CHF management and significantly influences disease prognosis [8].

Recent studies have shown a close association between frailty and cognitive dysfunction. In 2013, the International Academy of Nutrition and Aging (IANA) jointly with the International Association of Gerontology and Geriatrics (IAGG) proposed the new concept of “cognitive frailty,” defined as a heterogeneous clinical manifestation characterized by the coexistence of physical frailty and cognitive decline (excluding dementia) [13]. The prevalence of cognitive frailty in older patients with CHF is as high as 19.70%-49.4% [14, 15], and its pathological mechanism remains unclear, likely resulting from multifactorial effects. Compared to physical frailty or cognitive impairment alone, cognitive frailty is more likely to lead to severe consequences such as disability, dementia, and death [13, 16]. Older patients with CHF and cognitive frailty face a 1.55-fold increased risk of poor prognosis within one year [17]. Notably, cognitive frailty is reversible [18]. However, it is notable that that current research on cognitive frailty in heart failure patients predominantly remains at the level of exploring influencing factors, lacking interventional studies specifically targeting the population with heart failure complicated by cognitive frailty. Only interventional studies focusing solely on physical frailty or cognitive impairment are available.

Dual-task training (DTT) constitutes a strategy involving the simultaneous performance of two distinct tasks [17]. In recent years, it has garnered significant attention for its potential to concurrently enhance both physical and cognitive functions [19–23]. DTT primarily focuses on the integration of motor and cognitive training components. This combined approach may yield synergistic effects surpassing those achieved by single-domain interventions (isolated exercise or cognitive training alone), potentially mediated through mechanisms such as neural plasticity modulation and cognitive-motor resource reallocation [17, 24].

Empirical evidence demonstrates the superior efficacy of DTT in improving cognitive and motor functions across diverse populations. Research by Kim [25]. revealed that stroke patients undergoing DTT combining gait training with cognitive training exhibited significantly greater improvements in both cognitive and motor functions compared to those receiving single-task training. Notably, these gains maintained stability for two weeks post-intervention. For older adults with cognitive impairment, DTT not only improved cognition, mood, and activities of daily living but also proved more effective than resistance training alone [26]. Furthermore, a community-based study involving healthy older adults demonstrated that aerobic-cognitive dual-task training significantly enhanced cognitive performance during dual-task assessments, significantly outperforming groups receiving solely aerobic exercise or cognitive training [27]. Collectively, these studies substantiate that DTT effectively enhances multidimensional functional outcomes across populations, exhibiting unique advantages particularly in the synergistic enhancement of motor and cognitive functions.

Although DTT has demonstrated potential in improving cognitive and physical functions in the general older adult population, there remains a significant gap in its application among older adults with CHF and cognitive frailty. Existing DTT studies have predominantly focused on healthy older adults, stroke patients, or those with isolated cognitive impairment, with no reported interventions specifically targeting older patients with CHF. In older CHF patients with cognitive frailty, due to limitations in cardiopulmonary function, reduced exercise tolerance, and systemic inflammatory status [28], as well as declines in memory, attention, mental flexibility, and overall cognitive function [29], traditional DTT protocols may pose risks due to excessive intensity or inappropriate cognitive load. Furthermore, previous intervention studies have predominantly focused on a single dimension (e.g., exercise or cognitive training alone) [30, 31], overlooking the integrated intervention needs of cognitive frailty as a ‘physical-cognitive’ comorbidity. This study designed a single-center, randomized controlled trial (RCT) to explore the potential efficacy and safety of DTT as an adjunctive therapy for older patients with CHF and cognitive frailty.

Methods

Study design

This study is a single-center, randomized controlled, single-blind clinical trial designed to evaluate the efficacy and safety of dual-task training in older patients with CHF complicated by cognitive frailty. The experimental flowchart is shown in Fig. 1, and the intervention and assessment schedules are presented in Table 1. This study has been approved by the Ethics Committee of The Affiliated Hospital of Zunyi Medical University (approved number: KLLY-2024-036) and registered at Chinese Clinical Trial Registry (registration number: ChiCTR2500105453). The protocol satisfies the standard items for clinical trials according to the SPIRIT 2013 statement [32] (see checklist Additional file 1).

Fig. 1.

Flow diagram of the study. DTT: Dual-task training

Table 1.

Study timeline

Assessment Domain	Baseline (Month 0)	Intervention (Month 1)	Intervention (Month 2)	Intervention (Month 3)
Socio-demographics
age, sex, educational attainment, living conditions, etc.	X
Clinical Characteristics
New York Heart Function Classification, Ejection Fraction, Duration of Illness, etc.	X
Primary Outcomes
Cognitive function	X	X	X	X
Physical frailty	X	X	X	X
Secondary Outcomes
Exercise endurance	X	X	X	X
Quality of Life	X	X	X	X
Grip strength	X	X	X	X
Lower limb muscle strength	X	X	X	X

Participants

Participants will be systematically recruited from the Department of Cardiovascular Medicine at the Affiliated Hospital of Zunyi Medical University. Hospitalized patients diagnosed with CHF will undergo initial screening using predefined inclusion and exclusion criteria. For eligible candidates who provide written informed consent, final eligibility to participate in this study will be confirmed by a cardiologist.

Inclusion criteria

• 1. Age ≥ 60 years; Diagnosis of CHF meeting the criteria outlined in the Chinese Heart Failure Guidelines 2024 [1].

• 2. New York Heart Association (NYHA) functional class II-III.

• 3. Meeting the 2013 International Consensus Group [13] criteria for cognitive frailty: (a) Self-reported or caregiver-reported cognitive decline; (b) FRAIL scale score ≥ 1; (c) Montreal Cognitive Assessment (MoCA) score < 26 (with an adjustment of adding 1 point to the total score if educational attainment ≤ 12 years); (d) Absence of a clinical diagnosis of Alzheimer’s disease or other neurodegenerative dementias.

• 4. Voluntary participation in the study with provision of written informed consent.

Exclusion criteria

• 1. Presence of contraindications to exercise, such as acute myocardial infarction, malignant arrhythmia, or early-stage acute coronary syndrome.

• 2. Comorbid major physical illnesses (e.g., fractures, hemiplegia), significant impairment of limb mobility, or status post heart transplantation.

• 3. Diagnosis of severe psychiatric disorders.

• 4. Concurrent participation in other interventional studies.

Termination criteria

• 1. Patients who withdrew from the study or were lost to follow-up during the research process.

• 2. Patients who died during the treatment period.

• 3. Patients whose condition worsened and developed various acute complications.

Sample size

The sample size was calculated using the two-sample mean comparison formula N1 = N2 = 2[(tα + tβ)σ/δ]², where σ represents the estimated standard deviation of the two populations, and δ denotes the difference between the two population means. Using Montreal Cognitive Assessment as the primary outcome measure, with α = 0.05, β = 0.10, the table values t_α=1.96 and t_β=1.282 were obtained for a two-tailed test. Based on results from relevant studies [33], the population standard deviation σ for MoCA was 2.59, and the mean difference δ was 2.20. Substituting these values into the formula yielded N1 = N2 = 30. Accounting for a 20% sample attrition rate, the total estimated sample size was 72, with 36 cases each in the intervention and control groups.

Randomization, allocation concealment, and blinding

One researcher will generate random sequences using a computer’s random number generation function, employing sequentially numbered, opaque, and sealed envelopes to achieve allocation concealment. Another researcher will independently open the envelopes in sequence at a 1:1 ratio to assign participants to each group. Primary and secondary outcome measures will be assessed by researchers blinded to group allocation.

Intervention

Dual-task program: Based on the vulnerability of cardiopulmonary function and cognitive load tolerance characteristics in older patients with CHF [29, 30], this study developed a 3-month phased progressive DTT protocol through systematic literature review, integration of evidence-based findings, multidisciplinary expert panel meetings (involving cardiology, rehabilitation medicine, and geriatric cognitive specialists), and pilot testing. The protocol requires participants to simultaneously perform motor and cognitive tasks, divided into three phases: adaptation phase (months 0–1), progression phase (months 1–2), and intensification phase (months 2–3). The training frequency is 3 sessions per week, with each session lasting 30–60 min (detailed dual-task parameters are shown in Table 2).

Table 2.

Dual-task training protocol

Stage	Exercise task content	Cognitive training content
Adaptation period (months 0–1)	Warm-up exercises: Neck/Shoulder/Waist/Ankle movements/marching in place (5–10 min) Aerobic exercise: Slow walking /jogging (10–15 min) Resistance: Seated Elbow Flexion/Extension - Leg Cool-down: Breathing regulation + alternating limb stretching (5–10 min)	Computing Task: Forward/Backward Counting Attention training: Provide the antonym Memory task: Naming and detailed recall of single animal images
Progression (months 1–2)	Warm-up: Same as above (5–10 min) Aerobic exercise: Slow walking / jogging (20 min) Resistance: Resistance band exercises (8–10 reps × 3 sets) Cool-down: Same as above (5–10 min)	Calculation: Serial subtraction of 7 from two-digit numbers Attention training: Provide the antonym Memory: Naming and detailed recall of two animal images
Intensification (months 2–3)	Warm-up: As above (5–10 min) Aerobic: Slow walking/jogging (20–30 min) Resistance: Resistance band exercises (10–15 reps × 3 sets) Cool-down: Same as above (5–10 min)	Calculation: Serial subtraction of 7 from three-digit numbers Attention training: Provide the antonym Memory: Naming and detailed recall of three animal images

Exercise task content

The exercise program includes warm-up activities (neck, shoulder, waist, ankle movements, and marching in place), aerobic exercise (Slow walking/jogging), resistance training (body weight exercises for 0–1 months, transitioning to resistance band training for 1–3 months), and cool-down exercises (breathing adjustments and flexibility stretches). According to the guidelines, Rating of perceived exertion (6–20 scale)(RPE) is used to determine exercise intensity. The exercise intensity gradually progresses from the initial RPE 10–12 to RPE 12–14, while the duration of aerobic training and the number of resistance exercise sets are also increased accordingly. (see Table 3).

Table 3.

Exercise task content

Exercise task	Specific Components	Adaptation Phase (months 0–1)	Progression Phase (months 1–2)	Intensification Phase (months 2–3)
Warm-up	Mobility exercises for neck/shoulders/waist/ankles/marching in place	Duration: 5–10 min Intensity: RPE 10–12	Duration: 5–10 min Intensity: RPE 12–14	Duration: 5–10 min Intensity: RPE 12–14
Aerobic Exercise	Slow walking or jogging	Duration: 10–15 min Intensity: RPE 10–12	Duration: 20 min Intensity: RPE 12–14	Duration: 20–30 min Intensity: RPE 12–14
Resistance Exercise	Months 0–1: Seated elbow flexion-extension / leg flexion-extension (using body weight) Months 1–3: Chest expansion / leg press (using resistance bands)	Sets: 2 Reps: 5-10 Rest: 2–3 min Intensity: RPE 10–12	Sets: 3 Reps: 8-10 Rest: 2–3 min Intensity: RPE 12–14	Sets: 3 Reps: 10-15 Rest: 2–3 min Intensity: RPE 12–14
Cool- down	Breathing regulation + alternating limb stretching	Duration: 5–10 min Intensity: RPE 10–12	Duration: 5–10 min Intensity: RPE 12–14	Duration: 5–10 min Intensity: RPE 12–14

Cognitive training content

Cognitive training includes calculation tasks (progressing from forward counting to serial subtraction of 7 from three-digit numbers), attention training (Provide the antonym), and naming/memory tasks (animal picture naming, memorization, and detail recall), as detailed in Table 4.

Table 4.

Contents of cognitive training tasks

	Adaptation Phase (months 0–1)	Progression Phase (months 1–2)	Intensification Phase (months 2–3)
Computing task	Medical or nursing staff randomly provide numbers to the patient, who then counts forward or backward.	Medical or caregiving staff randomly provide the patient with a two-digit number, and the patient is to sequentially subtract 7 from this number continuously	Medical or caregiving staff randomly provide the patient with a three-digit number, and the patient is to sequentially subtract 7 from this number continuously.
Attention training	While maintaining straight-path walking at a steady speed, the patient is auditorily cued with monosyllabic Chinese characters (e.g., gāo ‘high’). The patient must verbally generate antonyms (e.g., dī ‘low’) within one gait cycle to ensure concurrent cognitive-motor engagement.	While performing straight-path walking at a fixed speed, the patient receives auditory verbal stimuli consisting of common disyllabic Chinese words (e.g., jian ying “hard”). The patient must verbally generate semantically opposite words (e.g., rou ruan “soft”) within one gait cycle to ensure concurrent cognitive-motor engagement.	While maintaining straight-path walking/jogging at a steady speed, the patient is auditorily cued with a trisyllabic word or tetrasyllabic Chinese idiom (e.g., guāng míng zhèng dà ‘open and aboveboard’). The patient must verbally generate its antonym (e.g. guǐ guǐ suì suì ‘sneaky’) within one gait cycle to ensure concurrent cognitive-motor engagement.
Naming and memory tasks	Medical staff or guardians present patients with distinctly recognizable animals. After the patient identifies them, family members ask the same questions again after 1 min. Following the patient’s response, additional questions about image details (such as colors in the pictures) may be asked.	Increase the number of animal pictures to two	Increase the number of animal pictures to three

Formation of the multidisciplinary implementation team

A dedicated multidisciplinary implementation team will be established for this study. Its composition and specific responsibilities are as follows: The team will comprise one cardiologist, one neurologist, one head nurse, one rehabilitation therapist, and six research nurses. The head nurse will serve as the team leader, overseeing overall coordination and quality control. The cardiologist will be responsible for the eligibility medical assessment of patients and cardiovascular safety management. The neurologist will focus on the assessment of cognitive function, monitor cognitive-related risks, and provide professional guidance on the setup of cognitive tasks within the intervention protocol. The rehabilitation therapist will be responsible for training and assessing the research nurses according to the established protocol to ensure standardized intervention delivery. The research nurses will undertake specific tasks, including health education, implementation of the training sessions, daily coordination, discharge preparation, and regular follow-up.

Intervention group

Participants in the intervention group will receive the dual-task training program in addition to routine care. The implementation process is as follows:

• Pre-training Safety and Adaptability Assessment: A joint evaluation will be conducted by a cardiologist and a neurologist. The cardiologist will assess the patient's physical condition and exercise safety, while the neurologist will perform baseline cognitive function assessments. Together, they will determine the patient's suitability for dual-task training. Training approval requires consensus from both specialists.

• Health Education and Guidance: Before training begins, a trained research nurse will provide health education on dual-task training (including its objectives, procedures, and precautions) to the patients and their families. Subsequently, the research nurse and a rehabilitation therapist will jointly demonstrate the training and provide practical guidance to the patient and family members. In addition, the research nurse will assist in establishing contact channels (collecting WeChat and phone numbers), distribute health education manuals and training materials, and share instructional videos via WeChat.

• In-hospital Training Arrangements: During hospitalization, patients and family members will complete dual-task training according to the schedule under the guidance of the research nurse or rehabilitation therapist, with real-time supervision and feedback provided.

• Pre-discharge Competency Assessment and Transition: Before discharge, the rehabilitation therapist and research nurse will jointly evaluate the ability of the patient and family members to independently and correctly perform the training program. They will address any questions to ensure a smooth transition from supervised in-hospital training to independent home-based training.

• Post-discharge Follow-up: The research nurse will conduct weekly follow-ups via phone or video to monitor training adherence, remind participants of training tasks, and promptly address questions from patients and family members. The rehabilitation therapist, neurologist, and cardiologist will provide remote professional support as needed.

Control group

Patients will receive routine care, including health education and guidance prior to discharge covering disease-related knowledge, medication administration, dietary care, psychological support, exercise methods, and self-care (e.g., self-monitoring of heart rate, blood pressure, blood glucose, infection prevention, and volume management).

Safety assessments

During hospitalization: Training shall be conducted under the supervision of researchers and family members. If the patient experiences symptoms such as chest pain, palpitations, shortness of breath, rapid breathing, dizziness, or blurred vision, exercise must be stopped immediately. A doctor should be called, and the time and details of the condition changes must be recorded. Preparations for emergency treatment should be made. If the patient’s condition is critical and requires resuscitation, assist the doctor in performing emergency procedures and conduct post-resuscitation observation, nursing care, and documentation. If a patient falls during exercise, immediately go to the patient’s side and notify a doctor. Do not move or reposition the patient. Measure vital signs and assess the patient’s consciousness, pupils, vital signs, and injuries. Based on the evaluation results, proceed with further examinations and symptomatic care. Investigate the circumstances of the fall, evaluate the surrounding environment, and eliminate any unsafe factors.

Post-discharge period: Perform exercises under family supervision. Monitor blood pressure and heart rate before and after training. Ensure proper warm-up and cool-down exercises. Diabetic patients should properly manage the interaction between exercise and medications, avoiding exercise during peak blood concentration periods of hypoglycemic drugs. Moderate food intake before and after exercise is recommended to prevent hypoglycemia. If symptoms such as dizziness, palpitations, or shortness of breath occur during exercise, stop immediately, rest on the spot, and measure blood pressure, pulse, and blood glucose while recording the results. Contact researchers promptly and seek hospital treatment if necessary. Educate family members on recognizing general cardiovascular conditions and provide first-aid training (e.g., Cardiac Pulmonary Resuscitation) to ensure a safe and supportive exercise environment for the patient.

Outcomes

All outcome measures will be assessed by trained, independent evaluators. To ensure the standardization and reliability of assessments, all research personnel involved in outcome evaluation must complete a unified training and certification process.

The training will be coordinated by the principal investigator and delivered by a team of specialists including a neurologist, a rehabilitation therapist, and a senior research nurse, each responsible for their respective expertise: The neurologist will provide training on the standardized administration and scoring of the Montreal Cognitive Assessment; the rehabilitation therapist will be responsible for training on the proper procedures for the FRAIL Scale and all physical performance tests (including the 30-second chair stand test, 6-minute walk test, and handgrip strength); the senior research nurse will train on the administration of quality-of-life questionnaires and standardized communication with patients. Following the specialized training, trainees will participate in supervised practical sessions, engaging in role-play with other trained research staff to master all procedures.

Upon completion of the training and practical sessions, trainees will be required to pass a formal competency assessment. During this process, each trainee will independently conduct a comprehensive assessment of 2–3 patients under the supervision of an expert. The expert will thoroughly evaluate the trainee’s performance in accordance with the standardized operational and scoring protocols for each assessment tool, focusing on procedural standardization, completeness of implementation, and scoring consistency. Only those who pass this assessment will be qualified to perform formal evaluations in the study.

The primary outcomes of this study are cognitive function and frailty status. Secondary outcomes include exercise tolerance, lower-limb muscle strength, handgrip strength, and quality of life.

Primary outcomes

Cognitive function

Cognitive function will be assessed using the Montreal Cognitive Assessment Scale, which was developed by Nasreddine based on clinical experience [34]. The scale consists of eight cognitive domains: visuospatial/executive function, naming, memory, attention, language, abstraction, delayed recall, and orientation, comprising a total of 12 items with a maximum score of 30. One point is added to the total score if the patient’s education level is 12 years or less. A total score of 26 or higher indicates normal cognitive function, while a score below 26 indicates cognitive impairment. The Chinese version of the MoCA has demonstrated good reliability and validity, with an internal consistency Cronbach’s α coefficient of 0.82 [35].

Physical frailty

Physical frailty will be assessed using the FRAIL Scale [], which was developed by the International Association of Nutrition and Aging in 2008. The scale includes five items: self-reported fatigue, resistance/endurance, ability to move freely, illness status, and weight loss, with a total score ranging from 0 to 5. A score of 0 is considered normal, 1–2 is considered pre-frailty, and ≥ 3 is considered frailty. Chinese scholars have translated this scale into Chinese and tested the overall Cronbach’s alpha of the scale to be 0.826, indicating good reliability and validity.

Secondary outcomes

Exercise endurance

Exercise tolerance will be assessed using the 6-minute walk test (6MWT) to evaluate patient functional capacity. The 6MWT is a safe, low-complexity, and highly reproducible method suitable for patients with heart failure [36]. An increase of 30–50 m in the walking distance is generally considered a clinically meaningful improvement [37].

Quality of life

Quality of life will be assessed using the Minnesota Living with Heart Failure Questionnaire (MLHFQ), a widely used international tool for evaluating quality of life in patients with chronic heart failure [38]. The MLHFQ comprises 21 items, including 8 items in the physical dimension, 5 items in the emotional dimension, and 8 items in other areas. Each item is scored on a Likert scale ranging from 0 to 5, with total scores ranging from 0 to 105. Higher scores indicate poorer quality of life.

Grip strength

The patient’s grip strength will be assessed using a grip dynamometer. During the measurement, the patient will stand upright with feet apart and arms hanging naturally. The patient will then grip the dynamometer with maximum force for more than 2 s, and the highest reading in kilograms will be recorded. Measurements will be taken alternately for each hand, with each hand measured three times. The maximum value among the three measurements will be taken as the patient’s grip strength.

Lower limb muscle strength

The 30-second chair stand test will be employed to assess the strength of the lower limb and core muscle groups in patients [39]. In this test, patients sit on a chair with their arms crossed over their chest. The number of times the patient transitions from a seated to a standing position within 30 s is recorded, with a higher number of repetitions indicating better lower limb muscle strength.

Data analysis

All statistical analyses will follow the intention-to-treat principle and will be conducted using SPSS 29.0 software. Continuous variables will be described as mean ± standard deviation (for normally distributed data) or median (interquartile range) according to their distribution; categorical variables will be described as frequency (percentage). Between-group comparisons of baseline characteristics will be performed using independent samples t-tests (for normally distributed variables), Mann-Whitney U tests (for non-normally distributed variables), or χ² tests (for categorical variables). To evaluate intervention effects, the primary analysis will employ linear mixed models. The model will use each outcome score as the dependent variable, with group (intervention/control), assessment time point, and group × time point interaction included as fixed effects, and a random intercept for individual participants specified as a random effect to control for correlations among repeated measurements. All primary outcomes (frailty score, Montreal Cognitive Assessment total score) and secondary continuous outcomes (grip strength, 6-minute walk distance, 30-second chair stand test repetitions, quality of life score) will be tested within this analytical framework.

The strategy for multiple comparisons and result interpretation is as follows: This study designates physical frailty score and Montreal Cognitive Assessment total score as two primary outcomes of equal clinical importance. Given that these two outcomes represent different dimensions of health outcomes (physical function and cognitive function), and improvement in either dimension has independent clinical value [40, 41], statistical testing for the two primary outcomes will be conducted independently at the α = 0.05 level, without multiplicity adjustment of the significance level (e.g., Bonferroni method). This strategy aims to avoid increasing the risk of Type II error (false negative) due to excessive correction, thereby more sensitively identifying potential benefits of the intervention in any single dimension. The analysis results for both primary outcomes will be completely reported. The criterion for a positive result is pre-specified as: the group × time point interaction effect reaches statistical significance (p < 0.05) for at least one primary outcome. If both are significant, this will support that the intervention has broader synergistic benefits.

We will calculate and report Cohen’s d (adjusted mean difference at the end of intervention divided by baseline SD) and partial η² for the “group × time point” interaction effect, both with 95% confidence intervals. The primary analysis will use linear mixed models to handle missing data under the MAR assumption; supplementary analysis will generate 20 datasets through the SPSS 29.0 multiple imputation module (under the MAR framework); if the missing rate for primary outcomes exceeds 10%, complete case analysis results will be reported. Sensitivity analysis will employ pattern-mixture models with δ=±0.5SD set for missing values in the intervention group to evaluate the robustness of conclusions under the MNAR assumption.

Discussion

The comorbidity of CHF and cognitive frailty has emerged as a significant challenge in the field of geriatric medicine. Currently, research on cognitive frailty in patients with chronic heart failure is still in its preliminary exploratory stage. Existing interventions are largely confined to improving physical frailty or cognitive impairment in a single dimension, lacking integrated intervention strategies specifically targeting CHF-related cognitive frailty. This study is a single-center, randomized controlled, single-blind clinical trial aimed at evaluating the efficacy and safety of dual-task training in older patients with chronic heart failure and cognitive frailty. The results of this study will provide reliable evidence for the progressive dual-task training intervention in this population.

The innovation of this study lies in breaking through the limitations of traditional single-intervention models: Previous evidence has shown that although exercise training alone can improve cardiopulmonary function in CHF patients, its effect on cognitive function is relatively limited [42]; Similarly, cognitive training alone has limited efficacy in enhancing physical function. If the study results confirm the effectiveness of dual-task training for CHF patients with cognitive frailty, it will provide the first evidence-based intervention program integrating both ‘physical-cognitive’ dimensions for this population. Compared with existing DTT studies, this program, through phased intensity adjustment and task adaptation, is the first to address the clinical challenges of low exercise tolerance and cognitive load sensitivity in CHF patients. Moreover, the research findings may contribute to the updating of CHF rehabilitation guidelines by incorporating DTT into the multidisciplinary management framework, thereby addressing the current lack of cognitive frailty intervention strategies in the guidelines.

The study limitations and corresponding strategies that need special attention include: (1) The sample size was estimated based on the effect size, which may be insufficient to detect subtle differences in secondary endpoints; (2) The implementation of the intervention relies on the active participation of patients, and patients with CHF may experience decreased compliance due to fatigue or dyspnea, which needs to be controlled through personalized intensity adjustments and regular follow-ups; (3) Cognitive assessments may be influenced by mood and testing environment, and although blinded assessments were used, bias may still exist. Future research could expand the sample size through multicenter collaboration and further validate the mechanisms by combining biomarkers (such as tau protein, inflammatory factors) and neuroimaging techniques.

Abbreviations

CHF

Chronic heart failure

DTT

Dual-task training

PRE

Rating of Perceived Exertion(6-20)

MoCA

Montreal Cognitive Assessment

6MWT

6-minute walk test

MLHFQ

Minnesota Living with Heart Failure Questionnaire

Authors’ contributions

XKW, XNL, and MT contributed to the conception and design of the protocol. XKW drafted the manuscript, and all authors (XKW, XNL, ML, MT, YMC, DW, FPG, JRJ, BEW, JMZ) critically reviewed, commented on, and approved the final manuscript for publication.

Funding

This study was supported by the Medical Research Union Found for High-quality health development of Guizhou Province Joint Fund Project (Grant No. 2024GZYXKYJJXM0164). The funding agency did not conduct an independent peer review of the study protocol.

Data availability

No datasets were generated or analysed during the current study.

Declarations

Ethics approval and consent to participate

The research protocol involving human subjects in this study has been reviewed and approved by the Biomedical Research Ethics Committee of the Affiliated Hospital of Zunyi Medical University. The patients/participants have signed written informed consent forms to participate in this study.

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.