1. Introduction
metabolic stress, fatigue, inflammation, muscle damage, Muscle hypertrophy, pain, RPE, hypertrophy, enlargement of individual muscle, muscle hypertrophy, restricted venous blood flow
HYPERTROPHIC, CONTRACTIONS, INCREASED BLOOD LACTATE, INFLAMMATION, RECRUITMENT, HYPOXIC, HYPERTROPHY
This study examined the acute effects of high-intensity resistance exercise with blood flow restriction (BFR) on performance and fatigue, metabolic stress, and markers of inflammation (interleukin-6 (IL-6)), muscle damage (myoglobin), angiogenesis (vascular endothelial growth factor (VEGF)). Thirteen resistance-trained participants (four female, 24.8 ± 4.7 years) performed four sets of barbell back-squats (75% 1RM) to failure under two conditions: blood flow restriction (BFR, bilateral 80% occlusion pressure) and control (CTRL). Completed repetitions and pre–post-exercise changes in maximal voluntary isometric contractions, countermovement jump, barbell mean propulsive velocity, and surface electromyography were recorded. Pre–post blood lactate (BLa) and venous blood samples for analysis of IL-6, myoglobin, and VEGF were collected. Ratings of perceived exertion (RPE) and pain were recorded for each set. Fewer repetitions were performed during BFR (25.5 ± 9.6 reps) compared to CTRL (43.4 ± 14.2 reps, Muscle hypertrophy, or the enlargement of individual muscle fibers, is an outcome of acute neural, hormonal, and muscular responses to resistance training, which leads to long-term adaptations in muscle hypertrophy and strength [More recently, blood flow restriction (BFR) resistance exercise has demonstrated its utility as an alternative method for inducing muscle hypertrophy. BFR exercise involves the use of a tourniquet, pneumatic cuff, or even elastic wraps to occlude distal blood flow in a limb. External pressure to the limb, by application and pressurization of the tourniquet, reduces arterial blood supply and venous return, with higher pressures restricting blood flow to a greater extent. This leads to an ischemic and hypoxic muscular environment causing high levels of metabolic stress. BFR in combination with low-intensity resistance training (20–30% 1RM) has been shown to produce greater muscle hypertrophy compared to low-intensity resistance training without BFR [Whereas hypertrophic response from HI-RT is associated with high mechanical tension and possibly muscle damage [Both HI-RT and LI-BFR are well-researched, effective modalities for promoting muscle hypertrophy. However, less is known about the potential utility of high-intensity BFR exercise (HI-BFR) to further enhance the hypertrophic capacity by maximizing mechanical tension and enhancing metabolic stress through restricted venous blood flow.Previous literature has demonstrated the occurrence of enhanced recruitment of higher-threshold motor units during LI-BFR [Additionally, high resistance loads increase the mechanical tension and subsequent muscle damage associated with RT, which are key anabolic signals for activating the mitogen activated protein kinase (MAPK) protein synthesis pathway, leading to increased protein synthesis and hypertrophy [The limited studies examining HI-BFR have demonstrated its utility for increased blood lactate concentrations [