Purpose: The purpose of this study is to examine the acute muscular and cardiovascular responses to applying blood flow restriction (BFR) before high-load training. Methods: Forty trained individuals visited the lab on three occasions. On Visit 1, participants completed paperwork and performed strength assessments. During Visits 2 and 3, participants completed four exercise conditions (one in each arm during each visit) as follows: (1) traditional resistance training (TRAD), (2) low load training with BFR (LLBFR), (3) low repetition high load training with pre-exercise BFR (PreBFR), and (4) low repetition traditional training (LRTRAD). Blood pressure, muscle thickness (MT), and isometric strength (ISO) were measured before and after exercise.Results: Data are displayed as means (SD). Immediately following exercise, MT in TRAD was greater compared with PreBFR (mean difference = 0.18[0.30] cm, p < 0.001) and LRTRAD (mean difference = 0.28[0.30] cm, p < 0.001). In addition, LLBFR demonstrated greater MT compared with PreBFR (mean difference = 0.24[0.30] cm, p < 0.001]. Immediately following exercise, ISO was lower in TRAD compared with PreBFR (mean difference = 33.8[46.9]N, p < 0.001) and the LRTRAD condition (mean difference = 32.8[50.4]N, p < 0.001). In addition, ISO was lower in LLBFR compared with PreBFR (mean difference = 43.9 [47.4]N, p < 0.001) and LRTRAD (mean difference = 42.9 [43.8]N, p < 0.001). Immediately following exercise, systolic blood pressure was greater in TRAD compared with PreBFR and LRTRAD. Conclusion:The application of BFR before engaging in high-load training does not seem to augment the muscular responses to exercise when compared with traditional high loads alone; however, it may pose less demand on the cardiovascular system.

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Resistance training volume has been suggested to be one of the most effective variables for developing muscular hypertrophy. Meta-analyses have concluded that there exists a dose-response relationship between weekly resistance training volume (i.e., the number of sets performed over the training week) and muscle mass accrual in nonresistance-trained individuals; however, experimental data in resistance-trained individuals have shown conflicting results. Current literature suggests that the performance of additional sets of resistance exercise within a single training session and training week does not inherently result in greater increases in muscle size compared with groups or conditions that perform lower volumes of resistance training. Notwithstanding these results, it has been suggested that controlling for each individual's previous training volume could improve the precision of the muscle hypertrophic response to resistance training and that failing to do so would disregard the principle of progressive overload. Herein, we explore the evidence for the suggestion that a higher-volume approach to training, in comparison to what an individual has been accustomed to, would improve the precision of the muscle growth response to resistance training and the physiological rationale that may (or may not) underpin this phenomenon.

Hammert, WB, Moreno, EN, Martin, CC, Jessee, MB, and Buckner, SL. Skeletal muscle adaptations to high-load resistance training with pre-exercise blood flow restriction. J Strength Cond Res XX(X): 000–000, 2023—This study aimed to determine if blood flow restriction (BFR) could augment adaptations to a high-load training protocol that was inadequate for muscle growth. Forty nontrained individuals had each arm assigned to 1 of 3 elbow flexion protocols: (a) high-load resistance training [TRAD; 4 sets to muscular failure at 70% 1 repetition maximum (1RM)], (b) low repetition high-load resistance training with pre-exercise BFR (PreBFR; 4 sets of 3 repetitions at 70% 1RM + 3 min of pre-exercise BFR), and (c) low repetition high-load resistance training (LRTRAD); 4 sets of 3 repetitions at 70% 1RM). Muscle thickness (MT), 1RM strength, and local muscular endurance (LME) of the elbow flexors were measured before and after 8 weeks. An alpha level of 0.05 was used for all comparisons. For the 50% site, MT increased for TRAD (0.211 cm, 95% confidence interval [95% CI]: 0.143–0.280), PreBFR (0.105 cm, 95% CI: 0.034–0.175), and LRTRAD (0.073 cm, 95% CI: 0.000–0.146). The change for TRAD was greater than PreBFR and LRTRAD. For the 60% site, MT increased for TRAD (0.235 cm, 95% CI: 0.153–0.317), PreBFR (0.097 cm, 95% CI: 0.014–0.180), and LRTRAD (0.082 cm, 95% CI: 0.000–0.164). The change for TRAD was greater than PreBFR and LRTRAD. For the 70% site MT increased for TRAD (0.308 cm, 95% CI: 0.247–0.369), PreBFR (0.103 cm, 95% CI: 0.041–0.166), and LRTRAD (0.070 cm, 95% CI: 0.004–0.137). The change for TRAD was greater than PreBFR and LRTRAD. One repetition maximum and LME significantly increased for each condition, with no differences between conditions. Collapsed across conditions 1RM strength increased 2.094 kg (95% CI: 1.771–2.416) and LME increased 7.0 repetitions (95% CI: 5.7–8.3). In conclusion, the application of BFR to low-repetition, high-load training did not enhance the adaptative response.