Post-stroke cognitive impairment (PSCI) stands out as a major sequela in patients after a stroke. It encompasses a range of cognition-related clinical syndromes, spanning from mild cognitive impairment to dementia, manifesting within 3–6 months following a stroke event (Sun et al., 2014; Koton et al., 2022; Rost et al., 2022). Patients with PSCI may grapple with impairments in diverse cognitive areas, including attention, memory, delayed memory, executive function, calculation, and visuospatial dysfunction, among others (Zhang and Bi, 2020; Kernan et al., 2021; Rost et al., 2022). Regrettably, PSCI tends to be overlooked compared to the more apparent physical disabilities (Liu et al., 2023). The overall prevalence of PSCI fluctuates between 20% and 80% (Sun et al., 2014; Ding et al., 2019). A recent multicenter cross-sectional study disclosed that the incidence of PSCI among Chinese individuals with a first-ever stroke was 78.7% (He et al., 2023). Notably, PSCI affects over one-third of stroke survivors, potentially leading to adverse clinical consequences (Mijajlović et al., 2017). It not only heightens the challenges of overall stroke patient rehabilitation, diminishes the quality of life, but also contributes to higher rates of disability and mortality, increased readmission rates, and ultimately imposes a substantial financial burden on caregivers and healthcare providers (Atteih et al., 2015; Obaid et al., 2020; Zhang and Bi, 2020). Consequently, early screening and management of PSCI emerge as urgent priorities.

Presently, PSCI treatment methods encompass pharmacological therapy (such as cholinesterase inhibitors: galantamine, rivastigmine, or donepezil) and non-pharmacological therapy (including cognitive training, exercise intervention, the motor-cognitive dual task training, acupuncture therapy, or lifestyle interventions, etc.) (Quinn et al., 2021). However, the long-term efficacy of pharmacological interventions remains uncertain, patient tolerance varies, and specific medication treatments may induce serious adverse effects, such as hepatotoxicity and gastrointestinal discomfort (Narasimhalu et al., 2010; Battle et al., 2021). Therefore, non-pharmacological interventions have garnered widespread attention. Exercise, as a crucial non-drug therapy, can enhance the quality of life in the general population and benefit the cardiovascular system and cognitive function in individuals after a -stroke (Huang et al., 2022).

The 2019 Canadian Stroke Best Practice Guidelines propose that exercise training can serve as an additional treatment method for cognitive deficits, encompassing various aspects like memory, attention, and executive performance (Lanctôt et al., 2020). Recent systematic reviews and meta-analyses reveal that exercise treatment not only enhances cognitive function but also improves motor function and activities of daily living in patients with PSCI (Li et al., 2023; Zhang et al., 2023). Hernandez and Gonzalez-Galvez (2021) synthesized the original studies on the impact of physical exercise programs on cognitive function in patients who suffered from a stroke to identify the best frequency, length, and type of program. They found that physical exercise programs were superior to rehabilitation programs for improving cognitive function. The recommended dose is at least 30 min per session, three sessions per week for at least 6 weeks. It is worth mentioning that motor-cognitive dual task training, a non-pharmacological intervention that combines motor tasks with cognitive tasks, has shown promise in reducing cognitive decline and improving quality of life in individuals with PSCI (Kim et al., 2014). However, since the primary focus of this study is to explore the optimal dosage of exercise therapy, studies that solely focus on motor-cognitive dual task training without a cognitive training control group should be excluded from this analysis. Conversely, studies that primarily involve motor-cognitive dual task training along with a cognitive training control group are suitable for inclusion in this review. Currently, numerous studies have confirmed the effectiveness of exercise on cognition for individuals with PSCI. Nevertheless, there remains a scarcity of research regarding the appropriate exercise dosage. Determining how to standardize exercise interventions to make them more systematic and reproducible remains a significant challenge. Therefore, further investigations are warranted to delve into the optimal exercise dose for patients with PSCI.

The American College of Sports Medicine (ACSM) recommends a regular land-based exercise program for most adults, which includes resistance, cardiopulmonary, flexibility, and neuromotor training. The ACSM also provides detailed exercise dosages, providing an important foundation for developing standardized exercise regimens (Garber et al., 2011). Chang et al. (2015) conducted exercise therapy in healthy young men following the ACSM guidelines and found that a session consisting of a 5-min warm-up, 20 min of moderate-intensity exercise, and a 5-min cooldown improved cognition. In contrast, shorter or longer durations of moderate exercise yielded negligible benefits. Currently, despite the increasing number of studies on exercise intervention for patients with PSCI, there is a lack of research evaluating exercise doses according to ACSM guidelines. As a result, the impact of varying exercise dosages on the cognition of PSCI patients is still debated. Therefore, further studies are needed to delve into the optimal exercise dosage for patients with PSCI. The objective of this study is to validate the efficacy of exercise in improving cognition and juxtapose the consequences of high and low/uncertain compliance following ACSM guidelines among patients with PSCI, to provide evidence for the development of more standardized, reproducible and effective exercise prescription.

This review strictly adhered to the guidelines outlined in the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) (Page et al., 2021) and was duly registered in PROSPERO (CRD42023487915).

In this study, we investigated the impact of different exercise doses on cognitive function in patients with PSCI. Our analysis was based on 18 studies which included a total of 1,742 participants. The results revealed that exercise intervention can enhance cognitive function in individuals with PSCI, aligning with previous research conclusions (Li et al., 2023; Zhang et al., 2023).

Previous studies have established that exercise, as a non-drug therapy, can be effective in improving cognitive function in patients with PSCI (Lanctôt et al., 2020). However, the effectiveness varies among different exercise interventions. Meta-analyses by Zhang et al. and Li et al. demonstrated that aerobic exercise, resistance exercise, or a combination of both had positive effects on cognitive function of patients with PSCI. Aerobic exercise particularly showed a significant clinical impact on enhancing cognitive function, while the other two exercise types exhibited moderate effects (Zhang et al., 2023). Lightweight and operable aerobic exercises were emphasized as having significant positive impacts on alleviating cognitive impairments after stroke (Li et al., 2023).

Exercise contributes to cognitive improvement through various mechanisms. First, it has the potential to enhance cardiorespiratory functionality, reduce brain atrophy, increase cerebral blood flow, facilitate neural connections, boost brain tissue metabolism, and stimulate excitation in the central nervous system (Szulc-Lerch et al., 2018). Second, by actively modifying vascular risk factors, exercise plays a pivotal role in preventing stroke, a key aspect of managing PSCI (Al Jerdi et al., 2020). Evidence suggests that exercise is effective in reducing risk factors for stroke, such as diabetes mellitus, coronary heart disease, high cholesterol, and hypertension, all of which contribute to vascular cognitive deterioration (Sahathevan et al., 2012). Additionally, exercise may enhance cognitive function by increasing the expression of growth factors like brain-derived neurotrophic factor, insulin-like growth factor-1, and vascular endothelial growth factor, thereby facilitating neurogenesis and angiogenesis (Cotman et al., 2007; Winter et al., 2007).

Beyond considering the type of exercise, it is crucial to examine the impact of varying exercise dosages on cognitive function in patients with PSCI. Existing evidence suggests that moderate-intensity exercise has the best effect on global cognition in patients with cognitive dysfunction after stroke, followed by low-intensity exercise (Li X. et al., 2022a). Initiating light-to-moderate intensity exercise early after a stroke may particularly improve memory, learning, and attention (Hasan et al., 2016). Recommendations from the American Academy of Neurology propose that engaging in exercise twice per week could potentially benefit cognitive function in individuals with cognitive dysfunction (Petersen et al., 2018). However, recent studies have shown mixed results, with some indicating no significant improvements in cognitive function with certain exercise intensities (Lapointe et al., 2022). Consequently, there remains a gap in research on exercise dosage for patients with PSCI, highlighting the need for further exploration of exercise intensity, frequency, total duration, and session duration.

In this comprehensive review, we synthesized information from various studies, incorporating different types of exercises, intensity levels, frequencies, durations, and other relevant indicators. Our analysis involved calculating exercise adherence scores based on ACSM recommendations, dividing the participants into a high compliance group and a low or uncertain compliance group based on scoring ratios. Subgroup analyses were then conducted on both groups to explore the impact of exercise dose on enhancing cognitive function in patients with PSCI.

The results from the subgroup analysis revealed a significant positive effect of exercise on cognitive function in both the high adherence and low/uncertain adherence groups [high SMD = 0.46, 95% CI (0.10, 0.82), low or uncertain SMD = 0.38, 95% CI (0.07, 0.70)], with statistical significance (p < 0.05). This suggests that exercise is beneficial for patients with PSCI over no exercise, irrespective of whether the exercise dose is highly compliant with ACSM recommendations. This finding aligns with the notion that exercise itself holds a high potential for improving cognitive function after a stroke (Li et al., 2023). However, the key difference in our study is the observation that high compliance with the exercise dose is more advantageous for enhancing cognitive function than low or uncertain compliance (high SMD = 0.46 > low or uncertain SMD = 0.38).

Examining the exercise types within the two groups, the ACSM high-compliance group involved various modalities such as aerobic training, physical exercise, resistance training, yoga, strength training, and eight-segment exercise training. Similarly, the ACSM low or uncertain adherence group included activities like walking, aerobic exercise, physical activity, passive movement training, resistance training, and strength training. Notably, the study aimed to mitigate the influence of major exercise types on differences in ACSM compliance. The primary recommended exercises in the ACSM guidelines encompass resistance exercise, aerobic exercise, and flexibility exercise, accompanied by detailed dosage recommendations for each modality. However, the majority of the literature included in the analysis focused on either a singular type of exercise or a combination of two types of training. Moreover, the descriptions of exercise dosage in the literature lack comprehensiveness. While some studies mentioned the mode and total duration of the exercise intervention, there was a notable absence or insufficient reporting on the intensity and frequency of the intervention. The term “individualized or individually tailored” was predominantly used to describe the exercise dose. Consequently, studies that should have been categorized as high adherence were mistakenly labeled as low or uncertain compliance. This misclassification may have influenced the overall findings and interpretations.

In clinical practice, it is essential to customize the exercise intervention dosage based on ACSM guidelines to provide personalized exercise regimens for patients with PSCI. The findings of this study emphasize the significant advantages linked to high adherence to the exercise dose recommended by ACSM guidelines compared to low or uncertain adherence. These results have promising clinical implications and serve as a benchmark for creating standardized and systematic exercise intervention programs. Therefore, we advocate for the early initiation of an appropriate exercise program for patients with PSCI under professional guidance. During exercise treatment, adjustments to the exercise dose should be made based on individual fitness, with a gradual strengthening of the dose while ensuring patient safety until it aligns with high compliance with ACSM recommendations. Future research should include additional RCTs with larger samples, multiple centers, and more rigorous research designs following the ACSM guidelines. This will help confirm our findings and establish a more scientific and reliable foundation for developing systematic, standardized, and repeatable exercise intervention prescriptions.

This article marks attempt to assess the impact of various exercise doses on cognitive function in individuals with PSCI based on the ACSM recommendations. As such, it introduces a topic with significant clinical implications. The research methodology employed is robust, featuring a comprehensive and rigorous search strategy. Additionally, a dual review process was implemented to uphold the accuracy and reliability of the research. The inclusion of only RCTs further enhances the quality of the evidence synthesized.

However, the study is not without limitations. Firstly, the pool of eligible RCTs addressing the influence of exercise on patients with PSCI remains limited. This scarcity underscores the need for more relevant studies in the future to expand the knowledge base in this domain. Secondly, the study does not consider several factors, including stroke timing, severity, subtype, infarction site, and individual characteristics such as age, sex, or other baseline factors. The omission of these variables may contribute to inevitable heterogeneity among the included studies. Additionally, while we mentioned the significance of motor-cognitive dual-task training in patient rehabilitation in the introduction, this aspect is not explored in detail within the main scope of our study, which focuses on determining the optimal exercise dosage for patients. Future research should consider conducting comprehensive studies on dual-task training to evaluate whether a combination of exercise and cognitive training offers greater benefits for PSCI patients and to investigate the underlying mechanisms. Lastly, despite promising findings, the results should be interpreted cautiously due to the observed high heterogeneity among the studies.

In our study, we observed a significant positive impact of exercise on cognitive function in patients with PSCI. Importantly, our findings indicate that high adherence to the exercise dose recommended by the ACSM guidelines had a more substantial effect on cognitive function in patients with PSCI than low or uncertain compliance to ACSM recommendations. This underscores the potential benefits of closely following the prescribed exercise guidelines for individuals dealing with PSCI.