Introduction

With the diversification of scientific training methods, improving cardiopulmonary function and optimizing body composition have become important issues for athletes and active participants. Cardiopulmonary function refers to the body's ability to deliver and utilize oxygen during exercise, with key indicators including the maximum heart rate (HR_max), the resting heart rate (HR_rest), cardiac output (CO), stroke volume (SV), maximal oxygen uptake (VO_2max), and maximal ventilation (VE_max) (Booher and Smith, 2003; Crisafulli et al., 2011; Park et al., 2010). These indicators not only relate to athletes' sports performance, but also largely determine exercise endurance and cardiovascular health for active individuals (Alvero-Cruz et al., 2020; Zhao et al., 2021). Research has shown that traditional moderate-to-high-intensity endurance training can effectively enhance cardiopulmonary function in athletes. However, for some active populations, particularly those with lower fitness levels, high-intensity training may pose injury risks or even overload the cardiovascular system (Trinity et al., 2012). Consequently, identifying training methods that can improve cardiopulmonary function at lower intensities has become an urgent topic in sports medicine and health sciences.

Blood flow restriction training (BFRT) combines low-intensity exercise with blood flow restriction using special cuffs on the proximal limbs to limit the blood flow. This technique induces high metabolic stress and mechanical tension in muscles under low-intensity conditions, thereby promoting improvements in cardiopulmonary function and muscle adaptation (Sato, 2005). Research has indicated that BFRT can effectively enhance key cardiopulmonary markers, such as VO_2max and VE_max, even under low-intensity conditions, thereby boosting aerobic metabolic capacity and performance in both athletes and active participants (Thompson et al., 2024). Additionally, BFRT has been shown to improve overall cardiovascular health by reducing the resting heart rate and optimizing cardiac output (Renzi et al., 2010).

Besides its impact on cardiopulmonary function, the BFRT's role in regulating body composition is equally noteworthy. Body composition is a critical indicator of physical fitness and health for athletes and active participants and includes measures such as the body mass index (BMI), the body fat percentage (BFP), the muscle cross-sectional area (CSA), and muscle thickness (MT) (Goonasegaran et al., 2012; Roelofs et al., 2015). These metrics not only affect sports performance, but are also closely related to the body metabolism, while optimizing body composition can enhance strength, endurance, and power (Gabbett et al., 2007). Recent studies have found that BFRT can significantly stimulate muscle hypertrophy and improve muscle mass by promoting local metabolic responses and protein synthesis (Geng et al., 2024; Martin et al., 2022). Under low-intensity conditions, BFRT can effectively increase the muscle CSA and MT and play a positive role in reducing the BFP, thus optimizing body composition (Kim et al., 2016; Korkmaz et al., 2022). As such, BFRT is a low-intensity, high-efficiency training approach that not only enhances sports performance and morphology, but also offers a new strategy for fitness maintenance and health promotion in active populations.

Notably, the application of BFRT presents certain health risks and limitations (Brandner et al., 2018). For instance, although BFRT is typically performed at low intensities (20–40% of 1RM or less than 50% of VO_2max), cardiovascular stress induced by this training modality may pose potential risks for individuals with a high risk of cardiovascular disease (Patterson et al., 2019; Renzi et al., 2010). Therefore, this study exclusively includes healthy individuals as research participants. Furthermore, most previous systematic reviews have primarily focused on BFRT’s effects on muscle strength and hypertrophy, with less emphasis on its effects on cardiopulmonary function and body composition in athletes and active participants (Grønfeldt et al., 2020; Perera et al., 2022). Although the aerobic benefits of BFRT have been demonstrated, its effects on the cardiac function and body composition of athletes and active participants remain controversial. Therefore, this meta-analysis aimed to evaluate the effects of BFRT on cardiopulmonary function and body composition, as well as to examine potential moderators influencing training outcomes. This study could provide scientific support for optimizing BFRT methods and offer safe, efficient training options for populations with varying fitness levels.

Methods

This meta-analysis followed the PRISMA guidelines (Moher et al., 2009), and registration was completed on inplasy.com (INPLASY202340052U1).

Results

Study Selection

A preliminary search through electronic databases yielded a total of 1,101 records, including three relevant studies identified from reference lists and Google Scholar. After removing 30 duplicates using EndNote X9 reference management software, 1,031 records were further screened based on inclusion criteria, resulting in their exclusion. A total of 40 studies were retained for inclusion in this meta-analysis. The detailed screening and exclusion process is illustrated in Figure 1.

Figure 1

Flow diagram of the search process.

Meta-Analysis Results

Outcomes from all included studies on the effects of BFRT on cardiopulmonary function and body composition included measures of cardiac function (HR_max, HR_rest, SV, CO), pulmonary function (VO_2max, VE_max), anthropometric measures (BMI, BFP), and muscle hypertrophy indicators (muscle CSA, MT, body girth). Detailed results are presented in Figures 2–5.

Figure 2

Forest plot of the effects of BFRT versus no-BFRT on cardiac function.

Figure 3

Forest plot of the effects of BFRT versus no-BFRT on pulmonary function.

Figure 4

Forest plot of the effects of BFRT versus no-BFRT on anthropometric measures.

Figure 5

Forest plot of the effects of BFRT versus no-BFRT on muscle hypertrophy.

Discussion

We conducted a meta-analysis of 40 studies with good quality assessments, encompassing a total sample size of 839 healthy athletes and active participants aged 14 to 33 years. The results indicated that compared to no-BFRT, BFRT interventions led to moderate improvements in pulmonary function (VO_2max and VE_max) and muscle hypertrophy (muscle CSA and MT) (ES = 0.73–0.88). However, there were no significant improvements (p > 0.05) in cardiac function (HR_max, HR_rest, SV, and CO), anthropometric measures (BMI and BFP), and body girth. Furthermore, subgroup analyses revealed that, compared to the non-BFRT condition, trained participants under the age of 23 demonstrated moderate improvements in VO_2max, the muscle CSA, and MT when undergoing endurance training interventions lasting less than six weeks and occurring less than three times per week.

Cardiac function refers to the heart's ability to maintain a stable blood flow within the circulatory system to meet the body's energy supply demands at varying intensities of exercise (Green et al., 1990). The findings of this study showed no significant improvements in cardiac function indicators with BFRT compared to no-BFRT (p > 0.05). Existing meta-analyses have also indicated no significant differences in the HR_rest between BFRT and no-BFRT in general populations and older adults (Wong et al., 2022; Zhang et al., 2022). However, BFRT has been shown to enhance the heart rate and cardiac output in young individuals in response to acute cardiovascular demands (Lemos et al., 2022). It is noteworthy that improvements in cardiac function may be related to acute compensatory changes in distal venous blood flow circulation due to cuff pressure (Fernandes et al., 2025; Pope et al., 2013). Specifically, during short-term BFRT, restricted venous return and increased vascular resistance can lead to decreased SV and an increased heart rate, thereby enhancing CO to maintain energy supply during exercise (Renzi et al., 2010). Therefore, long-term BFRT did not demonstrate significant positive effects on the improvement of cardiac function among athletes and active individuals. Additionally, the intervention protocols of BFRT may influence cardiac function indicators, and the existing literature on HR_rest, SV, and CO is limited (only three studies available), thus necessitating cautious interpretation of the findings related to cardiac function.

Pulmonary function reflects the ability of the lungs to inhale, exchange gases, and exhale air at different activity levels (Inbar et al., 1993). The results indicated that BFRT had a moderate significant effect on pulmonary function variables compared to no-BFRT (ES = 0.81–0.88). Previous meta-analyses have also shown that BFRT significantly improves VO_2max in healthy young individuals compared to no-BFRT (Formiga et al., 2020). However, the meta-analysis by Castilla-López et al. (2022) found that while aerobic capacity improved in athletes following BFRT, the intergroup differences compared to no-BFRT were not statistically significant (ES = 1.02; p = 0.064). In fact, the enhancement of aerobic capacity in pulmonary function may be attributed to dual adaptations at both central and peripheral levels, which accelerate physiological metabolism and synthetic responses, such as increased erythropoietin secretion in hypoxic environments and after exercise, thereby enhancing red blood cell and hemoglobin levels and improving oxygen delivery capacity and adaptability (Keramidas et al., 2012; Koistinen et al., 2000). During BFRT, ischemia and hypoxia modulate vascular endothelial growth factor and endothelium-dependent vasodilation, improving the efficiency of oxygen and carbon dioxide exchange as well as exercise endurance (Formiga et al., 2020). Therefore, BFRT demonstrates a more positive effect on pulmonary function among athletes and active individuals. Subgroup analyses showed that younger, trained participants experienced significant increases in VO_2max (ES = 0.85–1.74) following endurance training twice a week for less than six weeks. Previous meta-analyses have indicated that when cuff pressure is ≥ 130 mmHg, combining two to four weeks of aerobic exercise with BFRT leads to more pronounced improvements in aerobic performance in healthy young individuals (Bennett and Slattery, 2019; Yang et al., 2022). Notably, compared to strength training, endurance training (such as cycling and running) has a more pronounced effect on pulmonary function, primarily due to its long-term adaptive stimulation of the aerobic metabolism. Studies have shown that endurance training can promote capillary formation and mitochondrial biogenesis in skeletal muscles, thereby enhancing oxygen utilization efficiency (Holloszy and Coyle, 1984). Additionally, this may be attributed to the higher physiological adaptability and neural regulation capacity of young adolescents, as well as their lower metabolic accumulation (Radnor et al., 2018). Low-frequency, low-cycle BFRT may be more beneficial in activating aerobic metabolic pathways in the muscles of trained young individuals, promoting angiogenesis and enhancing oxygen utilization, ultimately improving the aerobic metabolism and maximum ventilation capacity (Formiga et al., 2020; Yang et al., 2022). The findings of this study suggest that low-frequency, low-cycle endurance training has more significant benefits for pulmonary function in trained young populations.

Anthropometric measures reflect body composition or proportions and are primarily used to assess the overall physical health status (Bhattacharya et al., 2019). The results of this study revealed that BFRT did not lead to significant improvements in anthropometric measures compared to no-BFRT (p > 0.05). However, a meta-analysis by Sun (2022) found that BFRT significantly reduced the BMI in obese adults (p = 0.02), although it had no significant effect on the BFP (p = 0.10). From a physiological perspective, the increased local metabolic stress experienced by obese adults during BFRT induces higher levels of lactate accumulation, which stimulates the release of growth hormone, promoting muscle synthesis and energy expenditure, thereby contributing to a reduction in the BMI (Karabulut and Garcia, 2017). It is important to note that significant reductions in the BFP primarily depend on lipolysis, and BFRT is less effective than traditional high-intensity training in initiating fat metabolism pathways, making it difficult to lower the body fat percentage through fat consumption alone (de Oliveira et al., 2016). For individuals of normal weight, the effects of metabolic stress from BFRT on the BMI and the BFP are relatively weak due to the stability of muscle-to-fat ratios, as well as lower basal metabolic rates and body fat levels (Kim et al., 2016). Therefore, the improvement effects of BFRT on anthropometric measures in athletes and active individuals are not significant.

Muscle hypertrophy indicators primarily assess changes in muscle size, shape, and growth, serving as measures of muscle quality (Buckner et al., 2016). The results of this study demonstrated that BFRT had a moderate significant impact on the muscle CSA and MT compared to no-BFRT (ES = 0.73–0.74), while it showed no significant effect on the body girth (ES = 0.18, p = 0.19). Previous meta-analyses have also indicated that BFRT yields greater improvements in muscle hypertrophy in trained individuals compared to high-intensity resistance training (HI-RT) (Geng et al., 2024). However, a meta-analysis by Lixandrao et al. (2018) found no significant difference in muscle quality improvement between BFRT and HI-RT for the general population and older adults. It is noteworthy that differences in sample size, study populations, and training status may significantly influence the analytical outcomes of these two meta-analyses. Muscle hypertrophy can be attributed to the activation of muscle growth pathways (such as mTOR and calcium neuron signaling pathways), leading to changes in muscle fibers and metabolic demands (Bodine et al., 2001; Fry et al., 2010). BFRT increases metabolic stress in muscles by restricting the blood flow, inducing the accumulation of metabolites such as lactate, causing moderate muscle damage, and promoting protein synthesis, thereby stimulating repair and remodeling mechanisms to enhance muscle hypertrophy (Fujita et al., 2007). Therefore, BFRT shows a more positive effect on muscle hypertrophy indicators in athletes and active individuals. Subgroup analyses indicated that younger, trained participants exhibited significant improvements in muscle hypertrophy after engaging in endurance training twice a week for less than six weeks (ES = 0.75–0.89). Previous meta-analyses have suggested that variations in age, duration, and frequency of training do not significantly affect the hypertrophy outcomes of BFRT in untrained individuals (Geng et al., 2024). Importantly, training status is considered a key factor influencing muscle hypertrophy outcomes, and the occlusion pressure does not serve as a determining factor for hypertrophy effects between BFRT and HI-RT (Geng et al., 2024; Lixandrao et al., 2018). Trained individuals possess higher muscle activation, metabolic stress tolerance, muscle repair capabilities, and cardiovascular adaptations. In contrast, active individuals without regular resistance training experience may have more difficulty in adapting to the high metabolic stress induced by blood flow restriction. Consequently, trained individuals exhibit significantly greater hypertrophy effects following BFRT compared to untrained individuals. This may be because younger trained individuals are more likely to activate cellular signaling pathways such as mTOR and ERK1/2 in the short term, enhancing the expression of growth factors and promoting muscle growth (Gundermann et al., 2012). Therefore, low-frequency and low-cycle endurance training has a more positive impact on muscle hypertrophy indicators in young trained individuals.

This meta-analysis has several limitations. Firstly, the data on cardiac function (such as HR_rest, SV, and CO) included in the studies were limited, comprising only three studies, which may restrict the reliability of the analysis results for these metrics. Secondly, this study did not account for gender differences. Given that the study population primarily consisted of male participants, there are insufficient female data to conduct subgroup analyses. Therefore, future high-quality research is needed to further validate and refine the predictive results of this analysis, providing a more comprehensive theoretical basis for BFRT.

Conclusions

This meta-analysis confirms the positive effects of BFRT on cardiovascular and pulmonary function as well as body composition in athletes and active participants. Specifically, the evidence indicates that BFRT significantly improves pulmonary function and muscle hypertrophy, while showing no significant effects on cardiac function and anthropometric measures. However, data regarding the impact of BFRT on cardiovascular variables such as HR_rest, SV, CO, and VE_max remain limited, with a low certainty of evidence, necessitating further research for validation. Subgroup analysis results indicate that BFRT is more beneficial for improving these physiological metrics when applied to young trained participants with the intervention duration of less than six weeks and a frequency of fewer than three sessions per week.