Blood flow restriction training attenuates changes in local muscle endurance: At odds with previous work?

Ida and Sasaki (2024) reported that exercising to failure without blood flow restriction resulted in greater increases in local muscle endurance than exercising to failure with blood flow restriction. The authors attributed their results (of their second experiment) to the differences in total exercise volume (i.e., load multiplied by the total number of repetitions over the training period) between conditions, and provided a correlation for support (Ida & Sasaki, 2024). Their correlation, however, appears to count each individual twice (i.e., n = 8 with 16 dots), which would violate the assumption of independence. Dr. Wernbom (2024) recently provided a viewpoint on Ida and Sasaki's study. We agree that more research is needed to better understand how low load resistance exercise with blood flow restriction impacts the mechanisms underlying improvements in muscle endurance. However, we also believe it is important to discuss Ida and Sasaki's findings in the context of the existing literature. More specifically, we believe their observation that blood flow restriction attenuated changes in local muscle endurance, and their explanation for such, should be acknowledged as being at odds with published studies.

Table 1 summarizes the characteristics and results of 10 blood flow restriction training studies that examined changes in local muscle endurance using pre- to post-intervention changes in the number of repetitions to failure (i.e., in a manner similar to that of Ida and Sasaki (2024)). In their introduction, Ida and Sasaki (2024) pointed out that, to their knowledge, the impact of blood flow restriction on exercise volume, muscle endurance adaptations, and their association has not been studied systematically. Over 10 years ago, however, Kacin and Strazar (2011) reported that exercising to failure with blood flow restriction improved local muscle endurance to a greater extent than a repetition-matched, low load training protocol performed without blood flow restriction (Table 1). In their discussion, Ida and Sasaki (2024) acknowledged the work of Kacin and Strazar (2011), and suggested that the discrepancies between studies highlight the importance of exercise volume for improving muscle endurance capacity. A few years after the Kacin and Strazar study was published, Fahs et al. (2015) compared muscular adaptations between low load resistance training with and without blood flow restriction in middle-aged men and women (i.e., 42–62 years). In comparison to Kacin and Strazar's study, Fahs et al.’s study was unique in that both training protocols exercised to failure. Fahs et al. (2015) observed similar increases in local muscle endurance, despite the fact that blood flow restriction significantly reduced the total exercise training volume. Two other studies (Buckner et al., 2020; Jessee et al., 2018) have demonstrated that performing very low load training (to or near failure) with and without lower blood flow restriction pressures led to similar increases in local muscle endurance. Importantly, the application of blood flow restriction resulted in fewer repetitions (and thus, total training volume) being performed across an 8-week training period (Buckner et al., 2020; Jessee et al., 2018). Indeed, in the study of Jessee et al. (2018), the application of a higher blood flow restriction pressure resulted in fewer repetitions (i.e., lower total training volume) being performed, yet actually enhanced local muscle endurance adaptations over and above very low load training (to or near failure) without blood flow restriction. Additional data have shown that higher applied pressures result in lower total training volumes, but similar increases in local muscular endurance compared to lower applied pressure (Buckner et al., 2020; Counts et al., 2016; Morley et al., 2021).

Ida and Sasaki (2024) concluded that blood flow restriction may impair changes in local muscle endurance compared to free flow exercise (i.e., exercising without blood flow restriction), which is at odds with previous research (Table 1). They (Ida & Sasaki, 2024) attributed their findings to the differences in total training volume between conditions, which is also at odds with previous research (Buckner et al., 2020; Fahs et al., 2015; Jessee et al., 2018). We are not suggesting that Ida and Sasaki (2024) should have acknowledged and discussed all 10 studies that are presented in Table 1, as some appear to be less relevant to their current design. However, in our opinion, it would have been helpful to at least discuss the Fahs et al. (2015) study, as well as those which prescribed lower load resistance training to or near failure with and without blood flow restriction (Buckner et al., 2020; Jessee et al., 2018). The literature suggests that performing low load resistance training to (or near) failure with blood flow restriction will likely reduce total training volume compared to low load training without blood flow restriction (Buckner et al., 2020; Fahs et al., 2015; Jessee et al., 2018). Yet, apart from the study of Ida and Sasaki (2024), it does not seem as though such reductions in total training volume will attenuate changes in local muscle endurance compared to performing low load resistance training without blood flow restriction (Table 1). We acknowledge that variation exists in the training protocols used across the highlighted studies, as well as how changes in local muscle endurance have been measured (Table 1), and that each study is not without its own set of potential limitations (e.g., within-subject unilateral training models). The discrepancies between Ida and Sasaki (2024)’s findings and the rest of the literature remain speculative, but may stem from Ida and Sasaki (2024)’s use of a one-set exercise training protocol. Perhaps multiple sets of exercise, as used in previous studies (Table 1), provides a stimulus that is capable of eliminating the attenuation observed with single-set blood flow restricted exercise. More research is needed to corroborate Ida and Sasaki's (2024) data and provide additional insight into how applying blood flow restriction during a single-set exercise training protocol impacts changes in local muscle endurance, perhaps compared to single- and multiple-set exercise protocols without blood flow restriction.

All authors approved the final version of the manuscript and agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All persons designated as authors qualify for authorship, and all those who qualify for authorship are listed.

None declared.

None.