The acute cardiorespiratory response to blood flow restriction strength exercise in healthy individuals: a randomized crossover trial

<bold>Introduction:</bold> Low-load strength training with blood flow restriction (BFR-ST) is a popular muscle strength training method similar to high-load hypertrophy training (TRA-ST). Acute cardiorespiratory response was compared between BFR-ST and TRA-ST protocols. BFR was expected to lower minute ventilation (VE, primary endpoint) and increase perceived leg exertion than TRA-ST. <bold>Method:</bold> A crossover randomized trial was done. The respiratory parameters were measured breath-by-breath. RPE (0–10) for dyspnea and leg fatigue was measured. Both protocols were performed on a leg press (TRA-ST: 3 sets, 8-12 repetitions with 70% 1RM; BFR-ST: 4 sets, 30/15/15/15 repetitions with 30% 1RM). Continuous BFR was applied to both legs at 70% arterial occlusion pressure. Analyzing all respiratory and RPE data adjusted for multiple measurements, linear mixed models reported mean differences [95% confidence interval]. <bold>Results:</bold> 24 healthy participants completed the trial (8/16 male/female, mean (SD) age: 30.5 (8.3) yrs., baseline VO_2peak: 47.5 (9.2) mL/kg/min, baseline VE_max: 117 (130) L/min). BFR-ST had reduced minute ventilation (VE) (−3.3 L/min [−4.6 to -2.1]), oxygen consumption (−0.12 L/min [−0.09 to -0.15]), and RPE breathing (−1.2 points [−1.5 to -0.9]) than TRA-ST. BFR-ST had greater RPE Leg (1.8 [1.3 to 2.2] points) and breathing rate (0.4 /min [0.5 to 1.2]) than TRA-ST. <bold>Conclusion:</bold> BFR-ST reduced VE and RPE Dyspnea compared to TRA-ST. Therefore, BFR-ST may appeal to rehabilitation patients wo struggle to exercise due to constraints such exercise-induced dyspnea. BFR-ST protocol feasibility and acute effects should be assessed in respiratory limited patients.