Central And Systemic Haematological Responses Are Similar Between Continuous And Intermittent Blood Flow Restricted Resistance Exercise: 3073 Board #3 May 29 3:15 PM - 5:15 PM

Resistance training (RT) with blood flow restriction (BFR) induces similar adaptations to traditional RT but uses markedly lower training loads. However, information about the acute exercise pressor, hemodynamic, and local metabolic cost of this training approach is sparse. These data are needed to understand the acute safety implications of this training approach and help identify an optimal BFR protocol. PURPOSE: To compare the acute central and systemic cardiovascular, and local metabolic responses to resistance exercise performed with continuous (BFR-C) and intermittent (BFR-I) BFR. METHODS: 12 resistance-trained males (mean ± SD) aged 22.3 ± 3.2yrs, 1.82 ± 0.06m, and 84.1 ± 9.0kg performed 4 separate acute resistance training sessions in a random order, each separated by 7 days. Training sessions involved four sets of squat-based RT at 30% of individuals’ 1 repetition maximum with 1) no BFR (CON), 2) BFR-C, 3) BFR-I, and 4) traditional high load training at 70% of 1 repetition maximum with no BFR (HL). Systemic blood pressure and derivatives of cardiac output, central aortic blood pressure pulse wave characteristics, and local blood volume and metabolism were assessed periodically during, and after each training session. Data were assessed by two-way ANOVA with Bonferroni-corrected post-hoc comparisons. RESULTS: All sessions similarly increase average metabolic demand, seen by a decreased tissue saturation index (-15%, 95% CI 13.3 to 17.4, p 0.05). Whilst changes in haemoglobin-derived Vastus Lateralis blood volumes were similar between conditions, they were higher with BFR-C than CON (6.97 μmol/L, 95% CI 0.2 to 13.6, p=0.04) and HL (7.9 μmol/L, 95% CI 1.2 to 14.8, p=0.01). Training equally increased mean systemic mean arterial pressure (MAP) (+70.5 to 76.6 mmHg, p<0.001) and cardiac output (+0.74 to 0.96 L, p<0.001) above baseline, with no difference between conditions. Training also equally increased mean aortic MAP (+14.8 to 24.2 mmHg, p<0.001) above baseline across conditions. CONCLUSIONS: BFR-C and BFR-I cause similar exercise pressor responses comparable with both traditional resistance training, and training without BFR. Adding BFR to resistance training didn’t exacerbate the magnitude or duration of the associated cardiovascular stress.