Impact of heart rate variability-guided, aerobic, and combined exercise training on cardiac autonomic function in cardiovascular patients: a systematic review

DONGHAI HUANG1, MUHAMMAD NUBLI ABDUL WAHAB2, CHIKA UMUNNAWUIKE3, CHIGOZIE CHARITY OKWUWA4, YUAN HOU1 PENGYUN ZHANG5, HENG WANG5

1School of Physical Education, Ningxia Normal University, Guyuan, China; 2Center for Human Science, University Malaysia Pahang Al-Sultan Abdullah, Pahang, Malaysia; 3Faculty of Chemical and Process Engineering Technology, Universiti Malaysia Pahang Al-Sultan Abdullah, Pahang, Malaysia; 4School of Chemical Engineering and Environment, China University of Petroleum Beijing at Karamay, Karamay, China; 5College of Physical Education, Henan Normal University, Xinxiang, China.

Summary. Aim. This review aimed to evaluate the effects of combined training, HRV-guided training, and aerobic training on cardiac autonomic function and other health-related outcomes in patients with cardiovascular disease (CVD). Review methods. A systematic search was conducted across nine electronic databases to identify relevant randomized controlled trials (RCTs). A total of 11 RCTs involving 489 participants were included. The quality of the 11 included studies was assessed using two study quality and reporting assessment scales (TESTEX and STARDHRV). Key points. Exercise interventions lasted 6–16 weeks, with 2–5 sessions per week and 30–60 min per session. Substantial heterogeneity was observed across studies in both exercise prescriptions and HRV assessment protocols. Evidence comparing different training modalities remains limited and inconsistent. Some studies reported improvements in vmHRV indices (RMSSD, HF (ms²), and SD1) following combined training or HRV-guided training, although these findings were not consistently replicated across studies. Aerobic training generally showed limited and heterogeneous effects on HRV outcomes. Exercise interventions, however, showed more consistent improvements in cardiorespiratory fitness and body composition. While current evidence does not support a definitive superiority of any single exercise modality, combined training and HRV-guided approaches show possible benefits for improving cardiac autonomic regulation and may inform individualized cardiac rehabilitation strategies. Future research may benefit from larger randomized controlled trials using standardized HRV assessment protocols.

Key words. Heart rate variability, cardiovascular disease, exercise therapy, autonomic nervous system, rehabilitation.

Impatto dell’allenamento guidato dalla variabilità della frequenza cardiaca, dell’allenamento aerobico e dell’allenamento combinato sulla funzione autonomica cardiaca nei pazienti cardiovascolari: una revisione sistematica

Riassunto. Scopo. Questa revisione mirava a valutare gli effetti dell’allenamento combinato, dell’allenamento guidato dalla HRV e dell’allenamento aerobico sulla funzione autonomica cardiaca e su altri esiti relativi alla salute in pazienti con malattie cardiovascolari (CVD). Metodi di revisione. È stata condotta una ricerca sistematica su nove banche dati elettroniche per identificare studi clinici randomizzati controllati (RCT) pertinenti. Sono stati inclusi in totale 11 RCT che hanno coinvolto 489 partecipanti. La qualità degli 11 studi inclusi è stata valutata utilizzando due scale di valutazione della qualità degli studi e della rendicontazione (TESTEX e STARDHRV). Punti chiave. Gli interventi di esercizio sono durati da 6 a 16 settimane, con 2-5 sessioni a settimana e 30-60 minuti per sessione. È stata osservata una sostanziale eterogeneità tra gli studi sia nelle prescrizioni di esercizio che nei protocolli di valutazione della HRV. Le evidenze che mettono a confronto diverse modalità di allenamento rimangono limitate e incoerenti. Alcuni studi hanno riportato miglioramenti negli indici vmHRV (RMSSD, HF (ms²) e SD1) a seguito di un allenamento combinato o guidato dalla HRV, sebbene questi risultati non siano stati replicati in modo coerente tra gli studi. L’allenamento aerobico ha generalmente mostrato effetti limitati ed eterogenei sugli esiti della HRV. Gli interventi di esercizio fisico, tuttavia, hanno mostrato miglioramenti più consistenti nella capacità cardiorespiratoria e nella composizione corporea. Sebbene le prove attuali non supportino una superiorità definitiva di una singola modalità di esercizio, l’allenamento combinato e gli approcci guidati dalla HRV mostrano possibili benefici per il miglioramento della regolazione autonomica cardiaca e possono fornire indicazioni per strategie di riabilitazione cardiaca personalizzate. La ricerca futura potrebbe trarre beneficio da studi randomizzati controllati su scala più ampia che utilizzino protocolli standardizzati di valutazione della HRV.

Parole chiave. Variabilità della frequenza cardiaca, malattie cardiovascolari, terapia fisica, sistema nervoso autonomo, riabilitazione.

Introduction

Cardiovascular disease (CVD) remains the leading cause of death worldwide, accounting for approximately 19.8 million deaths in 2022 alone, representing 32% of total global mortality1. To reduce the risk of recurrence and improve long-term prognosis, the restoration of cardiac autonomic function has become a central focus in CVD rehabilitation2. Although conventional pharmacological therapies play a key role in disease management, their capacity to restore autonomic regulation remains limited3. The cardiac autonomic nervous system (ANS) consists of the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS, also referred to as the vagus nerve). Together, these systems maintain cardiovascular homeostasis through top-down regulation mediated by the central autonomic network (CAN)4. Heart rate variability (HRV) is a widely used non-invasive marker reflecting the dynamic balance of the ANS and its regulatory flexibility5. Among commonly used HRV metrics, RMSSD, HF (ms²), and SD1 are interpreted as indices of cardiac vagal activity, collectively referred to as vagally mediated HRV (vmHRV)6-8. The definitions and physiological significance of the main HRV metrics are summarized in table 1.




In patients with cardiovascular disease, autonomic dysfunction is typically characterized by reduced vagal activity and lower vmHRV levels9. Lower vmHRV has been associated with adverse cardiovascular outcomes and poorer clinical prognosis9-11. Therefore, enhancing cardiac autonomic regulation, as reflected by vmHRV indices, may represent a potential target in cardiovascular rehabilitation. In this context, identifying effective strategies to enhance vmHRV and improve autonomic regulation in patients with CVD remains an important research priority.

Accumulating evidence indicates that exercise interventions are associated with improvements in cardiac autonomic regulation, typically reflected by increases in vmHRV across different populations12,13. In patients with CVD, structured exercise training has also been reported to improve vmHRV indices (RMSSD and HF), accompanied by reductions in resting heart rate and improvements in autonomic regulation14,15. In the context of cardiac rehabilitation, exercise-based interventions are widely recommended as an important component of treatment. Studies have shown that these interventions are associated with improvements in cardiorespiratory fitness and physical function16-18. These exercise interventions are typically implemented through different training modalities, most commonly aerobic training and combined (aerobic–resistance) training. In recent years, HRV-guided training has been proposed as a novel training strategy. This approach dynamically adjusts training intensity based on daily autonomic status reflected by individual HRV indices, thereby enabling more individualized exercise prescriptions19-21. However, the relative effects of different training modalities (aerobic training, combined training, and HRV-guided training) on improving autonomic regulation in patients with CVD remain unclear.

Several systematic reviews have examined the effects of exercise training on HRV. However, a considerable proportion of these reviews included non-randomized studies, crossover designs, or quasi-experimental studies, which are generally associated with a higher risk of bias12,15,22,23. In addition, some reviews lacked clear classification of exercise intervention types. Substantial differences in training protocols and study quality across the included studies further limited the interpretability and comparability of their findings24, 25. To address these methodological issues, the present review included only randomized controlled trials (RCTs) and conducted a structured comparison of different exercise training modalities (aerobic training, combined training, and HRV-guided training) in patients with cardiovascular disease. This study aims to compare the effects of different exercise training modalities on cardiac autonomic regulation in patients with CVD.

Methods

The review was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines26 and was prospectively registered in PROSPERO (registration number: CRD420251018026).

Search strategy

A systematic search was conducted across nine English-language databases, including PubMed, Web of Science, Ovid Medline, Embase, Scopus, CINAHL, PsycINFO, Cochrane Library, and SPORTDiscus. The Boolean search strategy combined the following terms using AND/OR operators: (“physical training*” OR “aerobic training*” OR “HRV-guided training*” OR “exercise*” OR “resistance training*”) AND (“HRV*” OR “heart rate variability*”) AND (“cardiovascular disease*” OR “cardiovascular diseases*”). Search strings were adapted as needed to accommodate differences in indexing terms and syntax across databases. The complete search strategies for nine databases are provided in supplementary 1 (table S1).

Study eligibility

The PICOS (Population, Intervention, Comparison, Outcome, Study design) framework26 was used to define the eligibility criteria for this review. Studies involving patients with cardiovascular disease (coronary artery disease, myocardial infarction, or peripheral arterial disease) were included. Eligible interventions comprised aerobic training, combined training (aerobic plus resistance), and HRV-guided training, with comparisons including usual care, no-exercise control groups, or alternative exercise modalities. Studies were required to report HRV outcomes, including time-domain, frequency-domain, or nonlinear indices. Only randomized controlled trials were considered. Further details are provided in table 2.




Study selection and data extraction

Zotero, developed by George Mason University, was used as the reference management tool to identify, and remove duplicate records. Two reviewers Donghai Huang (HD) and Chika Umunnawuike (CU) independently screened the titles and abstracts of all retrieved studies according to the PICOS criteria. Disagreements were resolved by a third reviewer Chigozie Charity Okwuwa (CCO). Data extraction was performed independently by the same two reviewers using a standardized Excel spreadsheet, and all extracted data were cross verified by Xiuling Zhang (XZ). Extracted variables included sample characteristics (sample size, age, sex), HRV measurement protocols (measurement method, breathing control, posture, sam-pling frequency), HRV parameters (LF ms², LF nu, HF ms², HFnu, LF/HF ratio, SDNN, RMSSD, pNN50%, TP, SD1), health-related outcomes (body weight, body fat percentage (BF%), BMI, BP, waist circumference (WC), VO₂max, recording duration, intervention characteristics (type, duration, frequency), and details of the control group. For further information on the physiological background of HRV metrics, refer to references7,27. If relevant data were missing, attempts were made to contact the corresponding study authors for clarification.

Classification of exercise interventions

For the purpose of comparative analysis, exercise interventions were classified into three categories: aerobic training (including HIIT), combined training (aerobic plus resistance), and HRV-guided training. This classification was informed by the recommendations of the American College of Sports Medicine (ACSM)28 and the 2021 ESC Guidelines on cardiovascular disease prevention29, and aligned with the FITT-VP framework in terms of exercise type and intensity structure. Where applicable, the classification was also consistent with the original study definitions.

In this review, HRV-guided training refers to an approach in which training load is adjusted on a day-to-day basis according to HRV measurements, typically derived from indices such as RMSSD20,21. Predefined decision rules are used to modify exercise intensity, with higher HRV values indicating readiness for higher training loads and lower values suggesting the need for reduced intensity or recovery sessions.

Quality assessment

To evaluate the methodological quality and reporting transparency of the included studies, two validated assessment tools were employed: the Tool for the assEssment of Study qualiTy and reporting in Exercise (TESTEX)30 and standard for reporting diagnostic accuracy studies guidelines for HRV research (STARDHRV)31. The TESTEX scale comprises 12 items with a total score of 15(including 5 points for study quality and 10 points for reporting) and is designed to assess aspects such as randomization, adherence, intervention reporting, and statistical analysis. In specific applications, the quality of the studies was classified according to their total TESTEX score as “high” (≥12 points), “good” (7–11), or “low” (≤6)32. The STARDHRV checklist, an adaptation of the original STARD guideline for diagnostic research, was modified to reflect the unique features of HRV studies. It includes 25 items (1 point per item) aimed at enhancing the clarity, transparency, and consistency of HRV study design, data processing, and reporting8,33. The evaluation tools were slightly adapted in this review34 details of the modifications can be found in supplementary 2 and 3.

Results

Selection and classification

A total of 2,102 records were initially identified through database searches, and one additional study were identified through manual reference checking. After applying all inclusion and exclusion criteria, 11 RCTs were included in the final analysis35-45. The study selection process is illustrated in figure 1.




In the absence of meta-analytic subgroup analyses, this review conducted a narrative, stratified synthesis of the included studies and compared the direction and consistency of effects across two dimensions: (1) HRV measurement protocols; (2) exercise prescription characteristics. Table 3 summarizes the general characteristics of the included studies, while table 4 presents the primary HRV outcomes and health-related physiological variables.













Study characteristics

The 11 RCTs (n=489) included patients with CAD36-38,41,42, post–myocardial infarction39,40,44,45, and peripheral arterial disease (PAD)33,41 (mean age ≈ 57 years; male=362, female=58, unreported=69). Most were sedentary or without systematic training.

There was marked heterogeneity in HRV assessment methods among the included studies. Measurement devices fell into three categories: electrocardiography (ECG)33,37,38,41,43, electrode chest belts37,38,41,42,44, and photoplethysmography (PPG)36. Recording conditions varied substantially, four studies explicitly reported breathing protocols (spontaneous breathing37, 12 breaths/min42,44, or a standardized breathing frequency40 whereas the remaining studies did not report breathing. Seven studies recorded HRV in the supine position35,37,40-44, one in the seated position36, and three did not report body position38,39,45. Recording duration was most commonly 5-10 min35,37,39,40,42-44, with other durations also used, including 60 s36, 3 min38, 15 min41, and 24 h45. Reporting of technical parameters was inconsistent; only five studies specified sampling frequency, ranging from 444 to 1000 Hz35,40,41.

The intervention groups in the three studies employed combined training37-39. Prescriptions were delivered over 8-12 weeks, 2-4 sessions per week, 30-60 minutes per session, comprising moderate-intensity aerobic work together with low-to-moderate resistance loads. One study alternated resistance and aerobic intervals (75-85% HRR) and progressed by shortening rest periods. The intervention groups in the two studies used HRV-guided training36,42, characterized by day-to-day individualized load decisions based on morning RMSSD; both applied short-term prescriptions (6-8 weeks), three sessions per week, 30-60 minutes per session. Aerobic training was the most implemented intervention and appeared in all 11 trials, either as the intervention or comparator condition. Among these trials, aerobic training served as the intervention in five studies33,39,41-43 and five as control group37-40,42. Overall, aerobic prescriptions typically spanned 6-16 weeks, with 2-5 sessions per week and 30-60 minutes per session. Two studies implemented HIIT36,40, with interventions lasting 8-9 weeks, three sessions per week, and 38-60 minutes per session, anchored at 85-100% HRmax or RPE 15-16.

HRV outcomes

Between-group comparisons across the three studies showed that, compared with aerobic training, combined training demonstrated greater between-group differences in RMSSD and SD37. Similarly, during the leg press test, greater between-group differences in SDNN and RMSSD were observed in the combined training group. However, no clear between-group superiority was observed during the cycling test38. In addition, greater between-group differences in HF (ms²) were reported in the combined training group compared with the aerobic control group (p < 0.016)39.

Across the two included studies, the HRV-guided training group showed greater increases in weekly mean RMSSD and greater reductions in resting heart rate compared with the aerobic control group42. Compared with the HIIT group, the HRV-guided training group showed lower LnRMSSDcv values, while no clear between-group differences were observed for other HRV indices36.

Across the studies that included aerobic training, patients with PAD demonstrated more favorable between-group differences in selected HRV indices (RMSSD, SDNN, and pNN50) following walking-based interventions43. Similarly, compared with control conditions, low-intensity pain-free walking was associated with slight improvements in PNS indices and reductions in SNS indices35. Water-based aerobic training showed significant between-group differences in nonlinear HRV indices, including Shannon entropy and normalized conditional entropy41. Differences were also observed across testing conditions: greater between-group differences in LF (ms²) were reported understanding conditions, whereas smaller or non-significant differences were observed at rest. In studies comparing moderate-intensity aerobic training with HIIT36,40, no clear between-group differences were observed in SDNN, LnRMSSD, or HF (ms²).

Health-related variables

Seven studies assessed health-related indices, including VO₂max, BMI, BF%, BP, and WC. Notably, four studies36,40,42,44 reported significant post-intervention increases in VO₂max. Three studies observed reductions in BMI and BF%39,41,44. Regarding blood pressure, most studies reported reductions in systolic blood pressure following the intervention35,42,44, while some studies also observed a decreasing trend in diastolic blood pressure36,40.

Quality assessment

This study assessed the methodological and reporting quality of the included studies using TESTEX and STARDHRV. Total scores are shown in table 3, item-level ratings are provided in Supplementary 4 and 5. The average score of the TESTEX was 11.81 ± 1.40 and ranged from 8.545 to 13.5 points36,44. Five studies were classified as high quality (score ≥12)34-36-38,42,44. Another six studies scored between 7 and 11 points, categorized as moderate quality.

The average of the STARDHRV score was 19.81 ± 1.67, with scores ranging from 16.536 to 2240,44. Five studies37,38,40,42,44 scored ≥ 20. An additional six studies35,36,39,41,43,45 had a score ≥ 16.5. All studies fulfilled criteria 1, 2, 5, 19, 20, 22, and 25. Notably, item 2145 and item 2342 each received a 0.5-point deduction.

Discussion

The review included 11 RCTs comparing combined training, HRV-guided training, and aerobic training with respect to autonomic function, using HRV indices as the primary outcomes and evaluating health-related indices. All exercise interventions lasted ≥ 6 weeks, with ≥ 2 sessions per week and ≥ 30 minutes per session. Substantial heterogeneity was observed in both exercise training protocols and HRV assessment methods, which limited the comparability of findings across studies. Within this heterogeneous and limited evidence base, derived from a small number of trials, three tentative patterns were identified. First, combined training showed limited and inconsistent between-group effects compared with aerobic training, with substantial variability in its effects on vagally mediated HRV across studies. Second, between-group evidence for HRV-guided training remains limited and inconsistent. Finally, aerobic training generally demonstrated modest and heterogeneous between-group effects, with responses appearing to depend on population characteristics and exercise prescriptions. Beyond HRV outcomes, exercise interventions improved cardiorespiratory fitness and body composition, whereas effects on blood pressure were inconsistent. In addition, TESTEX and STARDHRV assessments indicated overall moderate methodological and reporting quality among the included studies.

Heterogeneity in HRV measurement and exercise prescriptions

The included trials showed substantial variability in recording duration, body position, breathing strategy. These differences may lead to variability in HRV outcomes, thereby reducing comparability across studies. Current methodological guidelines generally recommend a 5-min short-term resting recording and the explicit reporting of body position and respiratory control7,10. Among the included studies, those using short-term (5-min) supine recordings with reported respiratory control showed an increasing trend in some vmHRV indices40,42,44. In studies using paced breathing with reported respiratory control, some studies observed increases in RMSSD without corresponding changes in HF40,42. Under spontaneous breathing conditions37, RMSSD also showed an improving trend. Differences in HF outcomes under varying respiratory conditions suggest that breathing strategy may influence the comparability of certain frequency-domain indices, particularly HF8,10,46.

Substantial heterogeneity was also observed in exercise prescription parameters across the included studies, particularly in intervention duration and weekly training volume, with some trials having relatively short intervention periods (≤6–8 weeks). Previous research suggests that longer intervention durations may be more favorable for improving vmHRV indices (RMSSD/HF) in older adults47. Regarding session duration, a 60-min exercise prescription was the most common among the included studies (5/11). Two HIIT protocols reported session durations of 38 min and 60 min, respectively40,48. Across the included studies, HRV responses under different session durations did not show a consistent pattern.

Overall, heterogeneity in HRV measurement conditions and exercise prescription design represents a key factor influencing the consistency of findings across studies. Therefore, when comparing the effects of different training modalities on HRV, these methodological differences should be considered as potential moderating factors. The present study systematically identified key sources of variability from both measurement and prescription perspectives, providing a useful reference for the standardization of future research designs.

Mechanisms underlying differences in hrv responses to excercise training

This study systematically compared the effects of aerobic training, combined training, and HRV-guided training on HRV in patients with cardiovascular disease. Although differences in HRV outcomes were observed across training modalities, no single modality demonstrated a consistent between-group advantage.

These differences are more likely attributable to variations in training structure, load organization, and HRV measurement protocols rather than a definitive advantage of any specific training modality. In combined training, the alternating or sequential integration of aerobic and resistance components varied across studies in terms of load distribution, recovery intervals, and training order37-39. These variations may induce fluctuations in autonomic responses and thereby affect the stability of between-group comparisons12. For HRV-guided training, the available evidence remains limited and inconsistent, which may be related to differences in HRV metrics and assessment timing. Different HRV indices reflect distinct dimensions of autonomic regulation49, while short-term pre-session measurements (60 s) are more susceptible to transient physiological fluctuations. In addition, variations in training load adjustment strategies, comparator interventions, and statistical approaches may further contribute to inconsistencies in findings.

Regarding aerobic training, although all included studies involved this modality, its effects on vmHRV were generally limited and inconsistent, with most studies showing no stable advantage over control conditions. These differences may be associated with variations in participant characteristics, exercise prescription design, and measurement conditions. Furthermore, in comparisons between moderate-intensity aerobic training and high-intensity interval training (HIIT), most HRV indices did not show a consistent advantage for either modality40,48.

Overall, heterogeneity in training structure, prescription dosage, and HRV measurement protocols appears to be a key factor influencing the consistency of findings across studies.

Health-related adaptations and their potential links to HRV

In addition to HRV outcomes, some included studies reported changes in health-related variables following exercise interventions. Overall, compared with no-exercise or usual care conditions, exercise training was generally associated with improvements in cardiorespiratory fitness and body composition. These changes may be relevant to cardiac autonomic regulation. From a mechanistic perspective, improvements in aerobic capacity (VO₂max) are typically associated with enhanced cardiovascular efficiency and greater stability of autonomic control50,51. Meanwhile, reductions in body weight, body fat percentage, and waist circumference may reflect improvements in metabolic status and inflammatory profiles, which are also closely related to cardiovascular risk and autonomic function52,53. Taken together, these adaptations may represent potential pathways through which exercise influences HRV responses54. However, these findings should be interpreted with caution. In the included studies, health-related variables were mostly reported as secondary outcomes, and their relationships with HRV changes were not directly examined. Therefore, the current evidence remains exploratory, and causal inferences cannot be established.

Research limitations and prospects

Several limitations should be considered when interpreting the findings of this review. First, the number of available RCTs remains limited, and most studies involved relatively small sample sizes, which may restrict the statistical power and generalizability of the findings. Second, substantial heterogeneity existed across studies in HRV assessment protocols and exercise prescription designs, reducing comparability between studies and hindering robust estimation and pooling of effect sizes. Third, several studies did not fully report key methodological details, such as control group interventions, HRV artifact correction procedures, and respiratory control protocols, which increase the complexity of interpreting HRV outcomes. Fourth, most included studies did not predefine clinical endpoints such as mortality, rehospitalization, or arrhythmia incidence, making it difficult to directly infer risks related to clinical events. Finally, restricting the search to English-language databases may have introduced language bias.

Future studies should include large-sample, multi-centre RCTs. HRV protocols should be standardized by incorporating nonlinear indices and artifact-correction methods to improve cross-study comparability and generalizability. It is also recommended to explicitly report training adherence and ensure that HRV measurements are taken at least 48 hours after the final training session to eliminate acute exercise effects55. Furthermore, future research should incorporate the TESTEX and STARDHRV frameworks to enhance reporting quality. It should also explore integrating pharmacological tracking, long-term adaptation mechanisms of cardiac autonomic function, and remote wearable technologies into home-based rehabilitation.

Conclusions

The review identified 11 RCTs through searches of nine databases and evaluated their methodological and reporting quality using TESTEX and STARDHRV. The available evidence comparing different exercise training modalities remains limited and heterogeneous. Across the included studies, between-group comparisons of vmHRV indices varied considerably among combined training, HRV-guided training, and aerobic training. Although some studies reported improvements in vmHRV indices (RMSSD, HF, and SD1) following combined training or HRV-guided training, these findings were not consistently replicated across studies or testing conditions. Therefore, the current evidence remains insufficient to support a stable advantage of any specific training modality in improving cardiac autonomic regulation in patients with cardiovascular disease. In addition, several studies reported improvements in health-related variables. Future research could benefit from larger, multicenter RCTs with standardized HRV assessment protocols, clearly defined exercise prescriptions, and comprehensive reporting of pharmacological treatments to enhance comparability and strengthen the certainty of the evidence.

Conflicts of interest. The authors declare there is no conflict of interest.

Authors’ contributions. Dr. Donghai Huang and Heng Wang conceived the article, completed the writing. Chika Umunnawuike performed the literature search and data editing. Chigozie Charity Okwuwa completed the literature search and language revision. Yuan Hou and Pengyun Zhang made optimizations in the writing of literature review.

Acknowledgment. I am very grateful to my supervisor, Mr Muhammad Nubli Abdul Wahab, for reviewing this article and providing a lot of revision suggestions, which contributed to the completion of this work.

Data availability. The study protocol was preregistered in the International Prospective Register of Systematic Reviews (PROSPERO) prior to data extraction and analysis, under the ID number CRD420251018026.

Supplementary materials. S1: The complete search strategies; S2: Description of each modified TESTEX criterion; S3: Description of each modified STARDHRV criterion; S4: Detailed results of the TESTEX scale; S5: Detailed results of the STARDHRV scale.



















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