Early-Phase Exercise-Based Comprehensive Cardiac Rehabilitation Program after Myocardial Infarction: A Randomized Controlled Trial

Abstract

Background

Myocardial infarction (MI) remains a leading cause of mortality and morbidity worldwide. Cardiac rehabilitation (CR) is an evidence-based intervention that improves cardiovascular outcomes; however, the optimal timing and contents of CR remain unclear.

Objectives

This study aimed to investigate the effects of an early-phase, exercise-based supervised comprehensive CR program on functional exercise capacity, grip strength, fatigue, sleep quality, and health-related quality of life (HRQOL) in patients with MI.

Methods

A randomized controlled trial was conducted involving 32 medically stable MI patients allocated to either an intervention or control group. The intervention group received a two-phase supervised CR program initiated within the first week post-MI, including inpatient and outpatient aerobic, calisthenic, and strengthening exercises for eight weeks. The control group received usual care. Primary and secondary outcomes included the 6-minute walk distance (6MWD), 30-second sit-to-stand test (30-sec STS), grip strength, fatigue (functional assessment of chronic illness therapy [FACIT]-fatigue), sleep quality (Pittsburgh Sleep Quality Index [PSQI]), and HRQOL (12-Item Short-Form Questionnaire and MacNew Heart Disease Health-Related Quality of Life Questionnaire).

Results

Compared to the control group, the intervention group showed significant improvements in 6MWD (mean difference [MD] = 97.3 m, p < 0.001), 30-sec STS (MD = 3.1 repetitions, p = 0.001), grip strength (MD = 5.7 kg, p = 0.04), FACIT-Fatigue score (MD = 8.8 points, p < 0.001), PSQI score (MD = -2.7 points, p < 0.001), and HRQOL subdomains (p < 0.05). No adverse events were reported.

Conclusions

Early-phase supervised CR significantly enhanced physical capacity, fatigue, sleep quality, and HRQOL in this cohort of MI patients. Early initiation of structured CR should be considered in clinical practice to promote faster recovery and improve long-term outcomes following MI.

Abbreviations

CI, Confidence interval

CR, Cardiac rehabilitation

FACIT, Functional assessment of chronic illness therapy

HRQOL, Health-related quality of life

MacNew, MacNew Heart Disease Health-Related Quality of Life Questionnaire

MD, Mean difference

mHealth, Mobile health

MI, Myocardial infarction

PSQI, Pittsburgh Sleep Quality Index

SF-12, 12-Item Short-Form Questionnaire

SF-36, 36-Item Short-Form Questionnaire

6MWD, 6-minute walk distance

6MWT, 6-minute walk test

30-sec STS, 30-sec sit-to-stand test

INTRODUCTION

Myocardial infarction (MI) is a severe form of coronary heart disease and a leading cause of death and physical disability, particularly in older adults.¹ Although percutaneous coronary interventions have reduced acute mortality rates, facilitating the full recovery and social reintegration of post-discharge patients continues to present clinical challenges.² Cardiac rehabilitation (CR) has been shown to reduce cardiovascular mortality and hospital readmissions, manage cardiovascular risk factors, and enhance aerobic capacity in patients recovering from MI.^2,3

CR is a comprehensive intervention that includes personalized exercise training, physical activity promotion, self-health education, and cardiovascular risk factor management tailored to the individual needs of patients with heart disease.⁴ The initial application of CR was limited to low-risk patients after MI; however, increasing evidence over the past two decades has supported the clinical benefits of CR and led to its inclusion as a routine recommendation in current guidelines.⁵ Consequently, comprehensive CR is now recommended for a broader range of patients, including those with acute coronary syndrome and heart failure with reduced ejection fraction.^6-8 Clinical practice guidelines from Europe, the United States, and Australia/New Zealand consistently emphasize that CR has the highest level of evidence for improving outcomes and delivering effective secondary prevention.^5,7,8 Moreover, modern CR programs aim not only to improve cardiovascular health but also enhance overall well-being and health-related quality of life (HRQOL).⁹ The benefits of structured exercise extend beyond the acute recovery phase, demonstrating sustained improvements in cardiovascular health indicators and highlighting the importance of initiating rehabilitation early in the clinical course.¹⁰

Over the last two decades, early-phase CR has been defined as commencing therapy in the second week post-discharge.¹¹ However, more recent evidence supports the safety and efficacy of initiating low-intensity exercise within the first week following MI.¹² Notably, recent studies have demonstrated the benefits of discontinuing bed rest within 12 to 24 hours and initiating bedside activities shortly after stabilization.¹³ Given that patients typically remain sedentary for much of the first week post-MI,¹² early mobilization and rehabilitation interventions become even more critical.

Exercise-based early-phase interventions have demonstrated efficacy in improving functional capacity and reducing recurrent cardiac events.^14,15 However, evidence supporting very early rehabilitation — such as initiation within the first three days following MI — remains limited.¹⁶ Although existing literature emphasizes the importance of initiating CR at the earliest feasible time, there is currently no consensus on the optimal timing for initiating exercise-based CR.^17-20 Therefore, further research is needed to evaluate the protocol, feasibility, safety, and clinical effectiveness of early supervised CR.

Accordingly, this study aimed to investigate the effects of early-phase exercise-based supervised comprehensive CR on functional exercise capacity, grip strength, fatigue, sleep quality, and HRQOL in post-MI patients.

METHODS

Study design and participants

This study was a single-center, randomized controlled trial of a phase I-II early intervention CR program with concealed allocation, blinded assessors and intention-to-treat analysis. The study was conducted between July 2023 and June 2024 at the Cardiology Department of Dokuz Eylül University Hospital, and included clinically and medically stable patients who had a first MI (either ST-elevation MI or non-ST-elevation MI) and were approved for phase I-II CR by a cardiologist. Participants were randomly assigned to the intervention group or control group with a 1:1 allocation ratiobased on a randomization sequence generated from the www.randomizer.org website by an investigator not involved in the study. Outcome assessors were blinded to group allocation. Although full participant blinding was not feasible due to the nature of the intervention, the participants were not informed of their specific group assignment or the characteristics of the interventions received by other groups. Therefore, they were considered partially blinded, which helped minimize potential expectation bias. The exclusion criteria were: 1) a history of coronary artery bypass graft surgery; 2) diagnosis of chronic renal failure, unstable angina, atrial fibrillation, severe and symptomatic aortic stenosis, or decompensated heart failure; 3) patients with orthopedic or neurological conditions that prevented exercise; 4) individuals with chronic obstructive pulmonary disease or asthma; and 5) those with a body mass index greater than 40 kg/m². Further exclusion criteria included the presence of exercise-induced myocardial ischemia, pericardial disease, or moderate-to-severe heart valve disease. Participants who did not have an ejection fraction of at least 20% (i.e., ejection fraction < 20%), and did not volunteer to participate in the study were also excluded.

This study was conducted in accordance with the Declaration of Helsinki and its later amendments and ethical standards, and it was approved by the institutional ethical board of Dokuz Eylül University (approval number: 2022/37-24, date: 23/11/2022). Informed consent was obtained from all participants before enrollment. The study was registered on ClinicalTrials.gov with registration number NCT06924034. We followed the CONSORT guidelines to report this study using functional exercise capacity as the primary outcome and grip strength, fatigue, sleep quality, and HRQOL as the secondary outcomes.

Assessments

Functional exercise capacity

Functional exercise capacity was assessed using the 6-min walk test (6MWT) and 30-sec sit-to-stand test (30-sec STS) on the day of discharge. The 6MWT was conducted following the American Thoracic Society guidelines.²¹ In brief, the participants were instructed to walk as far as they could between two cones in 6 minutes in a straight 30 m corridor, and the distance covered was recorded (6MWD). The 30-sec STS test was performed with a chair with no arms, legs with rubber tips (non-slip), a fixed height of 46 cm, and positioned next to a wall.²² The test started in a sitting position with the participant’s feet flat on the floor and their arms crossed at the chest, and they were then instructed to perform the sit-to-stand task as quickly as possible. A standard sit and stand was considered as complete straightening of the legs at the end of the sitting phase and a firm landing of the hips on the chair when seated. No encouragement was provided during the test protocol. Within the 30-second test period, the number of sit-to-stand repetitions completed by the participants was recorded.²² Heart rate, oxygen saturation and level of dyspnea and fatigue (using a CR-10 Borg scale) were recorded at baseline and immediately after each test. The participants were allowed to rest for 30 minutes between the two tests.

Grip strength

Hand grip strength was measured with a hand dynamometer (Jamar®, dynamometer/Promedics Ltd., Blackburn, Lancashire, UK) based on the American Society of Hand Therapist recommendations.²³ The measurement was performed with the patient in a seated position with the shoulder in adduction and forearm in a neutral position, elbow in 90° flexion, and wrist in in 0-30° extension. The mean of 3 measurements for each hand was recorded in kilograms.

Fatigue

Fatigue was assessed using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-Fatigue) scale, a validated tool consisting of 13 items that measure the fatigue of the patients in the last 7 days. Each item is scored between 0-4, and the total score ranges between 0-52. A high total score indicates lower fatigue.²⁴

Sleep quality

Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), which consists of 19 self-rated questions covering the following seven components: sleep quality, onset latency, sleep duration, sleep efficiency, sleep disturbances, use of sleeping medications, and daytime dysfunction. Each item is scored between 0-3, and the total score ranges between 0-21 points. A high score indicates poor sleep quality.²⁵

Health-related quality of life

HRQOL was measured using the MacNew Heart Disease Health-Related Quality of Life instrument (MacNew) and the 12-item short-form questionnaire (SF-12).²⁶ The MacNew questionnaire is a self-administered disease-specific quality of life questionnaire consisting of 27 items divided into the following 3 subdomains: physical limitations, emotional function and social function. The time frame for the MacNew questionnaire is the previous two weeks. Each domain is scored from 1-7 points. The overall score of the questionnaire is calculated by averaging all scored items. Higher scores indicate better HRQOL.²⁶ The SF-12 is a modified version of the 36-Item Short-Form Questionnaire (SF-36),²⁷ and it is an easy-to-administer quality of life questionnaire consisting of 12 questions with 2 subdomains (physical and mental health). It questions general health status, limitations in physical and social activities, activities of daily living, mental health and well-being, pain and general health perception. A high score indicates a state of well-being.²⁸

Procedure of the comprehensive CR program

We designed a comprehensive exercise-based and supervised CR program consisting of two phases. Phase I was an inpatient program, modified from the intervention described by Xu et al.,¹⁸ and lasted until discharge (Table 1). This was followed by an outpatient-supervised Phase II, which lasted eight weeks. According to established guidelines, low-risk patients with MI can be safely discharged within 72 hours of hospitalization.²⁹ To minimize the risk of complications, eligible patients were discharged by the cardiologist on day 4 after completing the final exercise session of Phase I, and Phase II CR was scheduled to begin 3 days later. In the intervention group, the participants in the inpatient phase received active-participatory lower extremity movements and progressive walking training (i.e., progressive walking in the room-corridor-hospital) to prepare them for discharge (Table 1). Inpatient phase I was conducted with supervision following the American Heart Association recommendations.³⁰ The participants in the intervention group then received Phase II of the supervised CR program, which was performed on 3 non-consecutive days within 1 week for 8 weeks as an aerobic exercise program. The aerobic exercise program consisted of 1 day of treadmill walking and 2 days of calisthenic aerobic exercises. Strengthening exercises were included in the program at the end of the outpatient 4th week and performed on the same day as the treadmill aerobic exercise. The participants were also asked to perform the strengthening exercises on at least 2 of the non-supervised days.

Table 1. Content of the comprehensive CR program for the intervention group.

Time	Content
Phase I (Hospitalization)
The first 12 hours	• Patients are to remain in bed. They are allowed to turn over in bed, move their limbs slowly and try to sit up, eat, defecate and brush their teeth
The first 12 hours to 1 days	• In-bed supervised: breathing exercise, diaphragmatic breathing, respiratory control
	• Exercise sitting at the edge of the bed: ankle, knee, hip flexion-extension: 3 sets of 5-10 repetitions
	• Try to get out of bed, sit on a chair 3 times/day for not more than 30 min at a time
	• Slowly walk in the room with assistance 3 times a day for 5-10 minutes each time
The first 2 days	• In-bed supervised: breathing exercise, diaphragmatic breathing, respiratory control
	• Exercises standing at the edge of the bed: ankle, knee, hip flexion-extension: 3 sets of 5-10 repetitions
	• Use the toilet without help
	• Walking in the corridor 3 times/day for 10-15 min at a time (with heart rate monitoring)
The first 3 days	• In-bed supervised: breathing exercise, diaphragmatic breathing, respiratory control
	• Exercises standing at the edge of the bed: ankle, knee, hip flexion-extension: 3 sets of 5-10 repetitions
	• Use the toilet and shower without help
	• Walking in the corridor 3-4 times/day for 10-15 min at a time (with heart rate monitoring)
The day of discharge	• In-bed supervised: breathing exercise, diaphragmatic breathing, respiratory control
	• Exercises standing at the edge of the bed: ankle, knee, hip flexion-extension: 3 sets of 5-10 repetitions
	• All basic life self-care without help
	• Walking in the hospital 3 times/day for 15-20 min at a time (with heart rate monitoring)
	• Climbing 1 flight of stairs
	• Schedule Phase II CR program
Phase II (after 3-4 days of discharge)	Phase II CR was performed supervised, 3 days a week (non-consecutive days, 1 day treadmill and 2 days calisthenic aerobic exercises) for 8 weeks as follows.
Treadmill	• Once a week, 40 minutes (including 10-min warm-up & 5-min cool-down) for 8 weeks
Calisthenic exercises	• Twice a week, 40 minutes (including 10-min warm-up & 5-min cool-down) for 8 weeks
Strengthening exercises	• Strengthening exercises included in the program at the end of the outpatient 4th week and performed on the same day of treadmill aerobic exercise. The patient was also asked to continue strengthening exercises taught on at least two of the non-supervised days

CR, cardiac rehabilitation.

The treadmill walking program consisted of 3 phases: (1) a 10-minute warm-up period, (2) a 25-minute loading period-progressively increasing according to modified Borg, and (3) a 5-minute cool-down period.¹⁷ For treadmill loading period intensity, walking speed was first calculated from the 6MWD at the start of the CR using the standardized speed formula (speed, km/h = 6MWD × 10/1000).³¹ Intensity was then initiated at 65%-75% of the participants’ 6MWD-derived speed, and progression was continued according to heart rate and responses to challenge with the modified Borg Scale (ranging from 0-10).³¹ For walking intensity, the participants were instructed to maintain a perceived exertion rating between 4 to 5 on the modified Borg Scale or reach ~ 60-70% of maximum heart rate corresponding to a mild-moderate exercise intensity according to current recommendations.³⁰ Exercise was terminated if the participants experienced excessive chest pain, severe dyspnea, or an extreme level of perceived exertion.

The calisthenics aerobic exercise program consisted of 3 phases (Table 1 and Figure 1): (1) a 10-minute warm-up period, (2) a 25-minute loading period-progressively increasing levels, and (3) a 5-minute cool-down period. For the loading period, we modified the "Royal Canadian Air Force XBX Fitness Program" calisthenic aerobic exercise program, which was originally designed to improve physical fitness in healthy sedentary individuals, and later applied in patients with cardiac conditions such as post-valve replacement surgery and chronic stable angina.^32-34 Some exercises from the original program were modified for patient safety, and new exercises were added to align with the study’s objectives. In addition, the program duration was extended to achieve an aerobic effect. The modified calisthenic aerobic program consisted of 15 exercises and lasted for a total of 25 minutes. The participants were instructed to perform each exercise continuously for a specified duration and number of repetitions without breaks. The program was structured into eight progressive levels, where exercise intensity was increased by increasing the number of repetitions. The participants were instructed to maintain a perceived exertion rating between 4 to 5 on the modified Borg Scale. They then progressed to the next level if they completed at least two sessions of the previous level within 25 minutes, without experiencing excessive chest pain, severe dyspnea, or extreme perceived exertion (a score of 7 or higher on the modified Borg scale). Details of the calisthenic aerobic exercise program are presented in Figure 1.

Figure 1.

Progressive calisthenics aerobic exercise program.

Strengthening exercises were included in the program at the end of the 4th week. The intensity of the exercise was determined according to 8 maximum repetitions and the patient’s perception of exertion at level 4-5 as determined by modified Borg.³⁵ According to this intensity, the color and/or free weight of an elastic exercise band was selected (the resistance of the bands varies according to their color). The exercises were performed as 1 set of 8-10 repetitions.³⁵ Eight different muscle groups were trained in each exercise session; knee flexors, knee extensors, hip flexors, hip extensors, trunk flexors, trunk extensors, shoulder flexors and shoulder extensors. Each exercise repetition included a slow and controlled movement with approximately 2 seconds of concentric contraction (with expiration) and 4 seconds of eccentric contraction (with inspiration). Progress was made by increasing the number of sets in the program by 1 unit every 2 weeks (up to 3 sets).³⁶

The patients in the control group followed a usual care program, which included guidance on the importance of continuing to perform physical activity initiated during inpatient care.

Statistical analysis

Continuous variables are expressed as mean ± standard deviation, and categorical variables are presented in absolute frequencies and percentages. All statistical analyses were performed using SPSS version 21.0 (SPSS, IBM Inc., Armonk, NY). Baseline characteristics of the groups were compared using an independent t-test, Mann-Whitney U test, or chi-square test as required. A univariate general linear model was used to conduct an analysis of variance to assess the treatment effect, with the group as a fixed factor. Mean differences are presented with 95% confidence intervals (CI) and effect sizes. The effect sizes are given as eta squared (η2) and thresholds are interpreted as small effect (0.01), medium effect (0.06) and large effect (0.14).³⁷ A p value < 0.05 was considered statistically significant.

The sample size was determined based on the findings of a previous study by Peixoto et al.,¹⁷ using an α level of 5% and a statistical power of 90%. Calculations were performed using the G*Power program (version 3.1.9.2),³⁸ considering the mean and standard deviation of the Global sub-dimension of the MacNew Heart Disease HRQOL questionnaire after the intervention reported in Peixoto et al.’s study (control group = 5.2 ± 1.0, intervention group = 6.1 ± 0.6). The minimum required sample size to detect a significant difference was 26 participants, with 13 in each group. To account for potential exclusions before the study, 40 patients were initially screened.

RESULTS

Forty patients with a first MI were screened to participate in the study. Eight of them were excluded before the study, and the remaining 32 were enrolled, with 16 in each group. No patients were lost to follow-up. The study flowchart is presented in Figure 2.

Figure 2.

Flow of the study.

Table 2 shows the demographic and clinical parameters of the patients. The mean age was 55.9 ± 8.0 years in the control group and 52.5 ± 5.4 years in the study group (p = 0.164). There were no significant differences between the groups in terms of demographic and clinical parameters (p > 0.05).

Table 2. Demographic and clinical parameters of the groups.

	Control group	Intervention group	p value
Age, years	55.9 ± 8.0	52.5 ± 5.4	0.164
Gender, male n (%)	13 (81.2)	16 (100.0)	0.226
BMI, kg/m2	26.1 ± 3.3	27.4 ± 2.5	0.221
Waist/hip ratio	1.0 ± 0.1	1.5 ± 2.1	0.624
Education, n (%)			0.195
Basic education	11 (68.8)	6 (37.5)
High school	2 (12.5)	3 (18.8)
University	3 (18.7)	7 (43.7)
Cardiovascular risk factors, n (%)
Hypertension	11 (68.8)	6 (37.5)	0.077
Hyperlipidemia	4 (25.0)	0	0.101
Diabetes	2 (12.5)	0	0.484
Smoking, yes	10 (62.5)	12 (75.0)	0.446
Smokers, pack.years	44.7 ± 17.6	41.3 ± 19.9	0.757
Clinical presentation
STEMI, n (%)	12 (75.0)	11 (68.8)	0.694
NSTEMI, n (%)	4 (25.0)	5 (31.2)
Systolic blood pressure, mmHg	120.6 ± 12.9	118.1 ± 18.9	0.665
Diastolic blood pressure, mmHg	80.8 ± 4.6	76.8 ± 12.9	0.257
Heart rate, bpm	76.5 ± 8.1	74.5 ± 9.1	0.517
Physical performance
6MWD, m	459.6 ± 35.8	466.4 ± 60.9	0.706
30-sec STS	11.9 ± 1.6	12.7 ± 2.0	0.246
Grip strength, kg	26.2 ± 7.9	27.9 ± 6.4	0.504

Data are expressed as mean (standard deviation) or n (%). p values were tested by Independent t test, Mann-Whitney U or χ² as required.

BMI, body mass index; MI, myocardial infarction; NSTEMI, non-ST-segment elevation MI; STEMI, ST-segment elevation MI; 6MWD, 6-min walk distance; 30-sec STS, 30-sec sit-to-stand test.

The 6MWD (mean difference [MD] = 97.3 meters, 95% CI = 58.8 to 135.7, η2 = 0.47, p < 0.001, Table 3, Figure 3), 30-sec STS (MD = 3.1 repetition, 95% CI = 1.3 to 4.9, η2 = 0.29, p = 0.001), grip strength (MD = 5.7 kg, 95% CI = 0.3 to 11.3, η2 = 0.13, p = 0.040), and FACIT score (MD = 8.8 points, 95% CI = 4.3 to 13.3, η2 = 0.35, p < 0.001) were significantly higher in the intervention group compared with the control group (Table 3). In addition, in the intervention group, an ≈ 22% increase was observed in 6MWD with an ≈ 26% increase in 30-second STS repetitions. Moreover, sleep quality based on PSQI score (MD = -2.7 points, 95% CI = -4.1 to -1.3, η2 = 0.35, p < 0.001) was significantly improved in the intervention group compared with the control group (Table 3). Furthermore, there was a significant increase in HRQOL in the intervention group compared to the control group according to subdomains of the SF-12 and MacNew Heart Disease HRQOL questionnaires (p < 0.05) (Table 3). The main findings of the study are summarized in the Central Illustration.

Table 3. Mean values and differences in outcome measures between groups after cardiac rehabilitation training.

Parameters	Control group	Intervention group	Intervention vs. control group
	Post training	Post training	Mean difference (95% CI)	Effect size (η2)	p value
6MWD, m	473.9 ± 47.3	571.2 ± 58.6	97.3 (58.8 to 135.7)	0.47	< 0.001
30-sec STS, repetitions	12.9 ± 1.7	16.1 ± 3.1	3.1 (1.3 to 4.9)	0.29	0.001
Grip strength, kg	26.8 ± 7.9	32.5 ± 7.3	5.7 (0.3 to 11.3)	0.13	0.040
FACIT score	41.1 ± 8.5	49.9 ± 2.2	8.8 (4.3 to 13.3)	0.35	< 0.001
PSQI score	5.4 ± 2.5	2.7 ± 1.0	-2.7 (-4.1 to -1.3)	0.35	< 0.001
SF-12 HRQOL questionnaires
Physical component score	50.9 ± 6.5	55.9 ± 1.4	5.1 (1.6 to 8.4)	0.23	0.005
Mental component score	49.8 ± 11.7	56.7 ± 3.5	6.9 (0.7 to 13.1)	0.15	0.031
MacNew Heart Disease HRQOL
Physical	6.2 ± 0.6	6.7 ± 0.2	0.6 (0.3 to 0.9)	0.31	0.001
Emotional	5.5 ± 0.8	6.4 ± 0.3	0.8 (0.4 to 1.3)	0.36	< 0.001
Social	6.3 ± 0.7	6.8 ± 0.4	0.3 (-0.1 to 0.8)	0.08	0.109
GLOBAL	5.9 ± 0.6	6.5 ± 0.2	0.6 (0.3 to 1.0)	0.34	< 0.001

Data are expressed as mean (standard deviation).

CI, confidence interval; FACIT, functional assessment of chronic illness therapy (FACIT) fatigue scale; HRQOL, health-related quality of life; PSQI, Pittsburgh sleep quality index; 6MWD, 6-min walk distance; 30-sec STS, 30-sec sit-to-stand test.

Figure 3.

Changes in 6-minute walk test distances based on groups.

Central Illustration.

Summarize of the study. CR, cardiac rehabilitation; FACIT, functional assessment of chronic illness therapy fatigue scale; HRQOL, health-related quality of life; MacNew, MacNew Heart Disease Quality of Life Instrument; MI, myocardial infarction; PSQI, Pittsburgh Sleep Quality Index; SF-12, Short Form 12 Health Survey; 6MWD, 6-min walk distance; STS, sit-to-stand test.

DISCUSSION

The main findings of this study showed that early-phase, exercise-based, supervised comprehensive CR significantly improved exercise capacity, grip strength, fatigue levels, sleep quality, and HRQOL in patients recovering from MI.

Early initiation of exercise-based CR has been associated with accelerated physical recovery, better prognosis, and enhanced quality of life after MI.¹⁶ Structured exercise regimens in CR programs aim to improve cardiovascular function, reduce hospital stay duration, and optimize long-term outcomes.¹⁷ Early participation in an exercise-based CR program has been linked to notable enhancements in cardiovascular health, and initiation of early rehabilitation has been associated with a shorter hospital stay among patients recovering from MI.^13,16-20 Xu et al. reported that an early, home-based CR model improved left ventricular function post-MI,¹⁸ while another review demonstrated significant reductions in body weight, enhanced physical activity levels, and improved cardiometabolic profiles following an 8-week CR intervention.³⁹ These findings are consistent with a meta-analysis by Haykowsky et al., which emphasized that early and sustained exercise is essential for optimal left ventricular remodeling post-MI.⁴⁰ In addition, existing evidence suggests that early-phase rehabilitation can improve functional exercise capacity and HRQOL.

Peixoto et al. conducted a randomized controlled trial and showed that patients who received early CR reported better functional abilities and greater satisfaction with their physical health compared to standard care.¹⁷ They implemented a supervised exercise program with early mobilization beginning 12 hours after MI, followed by an unsupervised progressive exercise program performed four days per week for one month after hospital discharge. The results showed that the HRQOL global score of the MacNew questionnaire was higher in the intervention group compared with the control group 30 days after discharge.¹⁷ Furthermore, physical and emotional subdomain scores were significantly higher in the intervention group, which also had a greater 6MWD compared to the control group. Lee et al. further demonstrated that structured exercise not only restored exercise capacity but also alleviated anxiety related to physical exertion, highlighting the psychological benefits of physical rehabilitation.⁴¹ In line with these findings, our study revealed higher scores in the subdomains of both the MacNew and SF-12 HRQOL questionnaires in the intervention group compared to the controls. In addition, participants in the intervention group achieved greater 6MWD and performed more 30-STS repetitions. These findings align with those of Tsai et al., who found that initiating early-phase II CR within 5-7 days post-MI significantly improved HRQOL subdomains assessed by the SF-36 questionnaire.¹⁹ Similarly, Yu and Yang reported that a home-based CR program initiated 12 hours after percutaneous coronary intervention led to substantial improvements in both 6MWD and HRQOL.²⁰ The minimally clinically important difference for the 6MWD in cardiac patients is reported to range between 25 and 50 meters.^42,43 Improvements beyond this threshold are considered clinically meaningful, reflecting enhanced functional capacity and better cardiovascular outcomes. In our study, the intervention group exceeded this threshold, achieving a mean difference of 97.3 meters in 6MWD compared to the controls.

To our knowledge, no previous studies have specifically examined the effects of early-initiated CR on grip strength in MI patients. However, phase II CR interventions have shown promising results.^44,45 For example, Campo et al. conducted a multicenter randomized trial involving four supervised sessions across four months post-discharge, supplemented by an individualized home-based program.⁴⁵ Their findings indicated improvements in grip strength, gait speed, HRQOL, and reductions in anxiety and depression. The intervention group also had lower rates of cardiac death and hospitalization for cardiac reasons. Similarly, Marzuca-Nassr et al. showed that a hybrid CR program comprising 10 supervised sessions including aerobic and resistance training followed by six weeks of home-based exercises significantly improved grip strength and functional capacity in older adults with coronary artery disease. Their findings confirm that structured physical activity can enhance grip strength.⁴⁴ In our study, we also observed a significant increase in grip strength in the intervention group. Talen together, these findings confirm that CR contributes to muscular strength recovery, which is crucial for improving the overall physical capabilities of cardiac patients.

Fatigue, a common issue in CR, is frequently associated with sleep disturbances and psychological stress. Le Grande et al. emphasized that post-cardiac event sleep disturbances can hinder rehabilitation progress and exacerbate fatigue.⁴⁶ The interrelationship between sleep quality, fatigue, and adherence to rehabilitation has also been highlighted in previous studies. For example, Yao et al. investigated the effects of music therapy combined with rehabilitation, and reported improvements in overall quality of life, although not specifically targeting fatigue.⁴⁷ Ghane et al. further demonstrated that sleep-targeted interventions integrated into CR can alleviate fatigue symptoms.⁴⁸ These findings emphasize the interconnected nature of sleep and fatigue and support the need for comprehensive, multidimensional CR programs. Lodi-Rizzini et al. also found that participating in CR led to enhanced sleep quality, while Risom et al. reported improvements in sleep initiation and maintenance among cardiac patients enrolled in structured CR programs.^49,50 Despite existing evidence supporting the benefits of exercise-based interventions for sleep improvement, to our knowledge, no prior studies have specifically examined the effects of early-phase, supervised comprehensive CR on sleep quality and fatigue in MI patients. Our study fills this gap, demonstrating that early CR significantly improved sleep quality and reduced perceived fatigue. These improvements are clinically relevant, as enhanced sleep quality can reduce daytime fatigue and contribute to better overall functional recovery in cardiac patients.

Future directions

While our study demonstrated the effectiveness of an early-initiated, face-to-face, supervised comprehensive CR model in post-MI patients, the evolving landscape of CR delivery, and particularly the growing prominence of mobile health (mHealth) interventions, offers promising opportunities for broader implementation and accessibility.⁵¹ The delivery of CR has undergone substantial transformation following the COVID-19 pandemic, with remote and personalized interventions gaining prominence. Recent evidence indicates that mHealth platforms can effectively facilitate CR delivery, promote patient engagement, and improve clinical outcomes.^52,53 Early initiation of mHealth interventions after MI, including the use of smartphone applications, wearable devices, and telemonitoring, represents a promising strategy to maintain patient activation and enhance adherence to secondary prevention behaviors.⁵¹ Furthermore, the integration of mHealth technologies and the prioritization of patient activation are increasingly recognized as essential components of contemporary CR models, enabling the delivery of individualized, flexible, and scalable rehabilitation programs that address diverse patient needs.^54-56 Therefore, leveraging mHealth platforms and enhancing patient activation are becoming critical elements for modern CR programs. Future research should focus on optimizing these approaches to further improve participation rates and long-term outcomes in CR.

Strengths and limitations

To our knowledge, this is the first supervised CR program to initiate both phase I and phase II rehabilitation at such an early stage, integrating traditional aerobic, calisthenic, and resistance exercises into a comprehensive protocol. Despite these strengths, the study has several limitations. It was conducted at a single center with a relatively small sample size, which may limit the generalizability of the findings. Although the calculated sample size was achieved and large effect sizes were observed, larger multicenter trials are needed to confirm the effectiveness of the program. In addition, the absence of adverse events suggests that future studies could explore the inclusion of more complex or higher-risk patient populations.

New knowledge gained

This study contributes to a deeper understanding of the clinical value and feasibility of initiating a supervised, exercise-based CR program in the very early phase following MI. The findings showed that early CR — commencing within days of the acute event — resulted in significant improvements in functional exercise capacity, muscular strength, fatigue reduction, sleep quality, and HRQOL. Furthermore, incorporating a structured and progressive combination of aerobic, calisthenic, and resistance training proved both safe and effective, offering a comprehensive approach to post-MI recovery. These outcomes underscore the importance of early mobilization and multi-modal rehabilitation strategies in optimizing patient outcomes and redefining the timing and scope of conventional CR programs.

CONCLUSIONS

In conclusion, the early-phase exercise-based supervised CR program post-MI in this study significantly improved the patients’ physical capabilities and improved their overall quality of life. Health providers should consider implementing structured CR programs shortly after MI events to maximize patient recovery and long-term health outcomes.

DECLARATION OF CONFLICT OF INTEREST

All the authors declare no conflict of interest.

FUNDING STATEMENT

This research did not receive any specific grant from funding agencies in the public, commercial, or non-for-profit sectors.