4. Discussion
metabolic stress, fatigue, neuromuscular fatigue, muscle damage, pain, Post-exercise fatigue
INFLAMMATION
To the best of our knowledge, this is the first study to examine the acute effects of bilateral limb BFR during high-intensity barbell back-squats. The purpose of this study was to examine the effect of bilateral BFR during high-intensity resistance exercise on performance and fatigue, metabolic stress, and plasma markers of muscle damage, inflammation, angiogenesis. Findings indicate the utility of bilateral HI-BFR back-squats for earlier onset of fatigue during exercise, with similar decrements in post-exercise performance, although associated with significantly higher pain perception. Additionally, the addition of BFR enhances acute post-exercise inflammation.In this study, participants performed significantly fewer total repetitions in the BFR condition compared to the CTRL condition (25.8 ± 8.5 reps vs. 42.2 ± 13.4 reps, respectively). Contrary to our findings, Winchester et al. observed no difference in the total number of repetitions performed between BFR and CTRL (47.0 ± 4.25 vs. 44.92 ± 3.13, respectively; Enhanced fatigue during BFR exercise has been associated with metabolic stress and the accumulation of metabolites. The restriction of blood flow and reduction in available OConsistent with Winchester et al. [Post-exercise fatigue was measured through changes in neuromuscular performance assessments and surface electromyography. Reductions in MVIC-EXT were non-significant, but consistent across conditions and MVIC-FLEX experienced significant reductions in peak torque which was also not different across conditions. Significant reductions, but consistent across conditions, were observed in MPV and CMJ, indicating neuromuscular fatigue [Low-intensity (20% 1RM) BFR resistance exercise has been found to significantly increase plasma IL-6 following five sets of knee-extension to fatigue [In line with previous findings in low- [This study is not without limitations. Participants in the current study were classified as advanced resistance-trained and each had a minimum resistance training background of one year; therefore, the findings of the current study may not be applicable to untrained individuals or clinical populations. Total work (number of repetitions) was not matched between conditions and may have influenced the outcome in post-exercise measures, limiting interpretation. However, a goal of this study was to explore how BFR affects performance/fatigue during HI-RT, which traditionally has fewer repetitions per set than lower-intensity loads. A matched workload between conditions may allow for a better comparison of the acute effects between exercise conditions. Lastly, the BFR in the current study was interrupted following set 2, and therefore was not a truly continuous application of BFR during the exercise stimulus. As this was one of the first studies examining high-intensity resistance exercise in conjunction with BFR, the authors were cautious with the BFR application, and future research should examine truly continuous BFR with an optimized matched work–load exercise stimulus design. Additionally, future research may benefit from examining the utility of lower restriction pressures during HI-BFR to potentially decrease the perceived pain.