Interindividual Variability of Acute Cardiovascular Responses to Low-Load Resistance Exercise with Different Methods of Blood Flow Restriction

PURPOSE: The aim of the study was to determine if acute cardiovascular responses to low-load resistance exercise with blood flow restriction (BFR) exhibit true and repeatable interindividual variability, and whether responses differ between absolute and relative pressure application methods. METHODS: In a replicate crossover design, 82 healthy adults (21 3 yr) were randomly assigned to an absolute (100 mm Hg; n = 42) or relative (80% arterial occlusion pressure ~128 mm Hg; n = 40) pressure group and completed two exercise and two control trials (randomized order). Exercise involved two sets of 30% one-repetition maximum unilateral knee extensions under the assigned pressure, with repetitions individually prescribed as 70% maximum achieved during pretesting. Systolic blood pressure (SBP), diastolic blood pressure (DBP), and heart rate (HR) were measured pre- and posttrial, and control-adjusted responses were calculated. Within-participant linear mixed models (covariate adjusted) and random-effects meta-analyses quantified interindividual variability, while Pearson correlations assessed reproducibility. RESULTS: BFR exercise increased SBP (18.0 mm Hg), DBP (12.8 mm Hg), and HR (4.5 bpm) versus control (all P < 0.001), with greater increases in SBP (4.9 mm Hg) and DBP (4.1 mm Hg) for the relative group ( P ≤ 0.001). Participant-by-treatment interactions indicated true interindividual variability for all outcomes except HR in the absolute group. Correlations between replicates were significant for all outcomes under relative pressures ( P ≤ 0.018), but only for SBP ( P < 0.001) in the absolute group. CONCLUSIONS: Acute cardiovascular responses to BFR exercise are variable between and reproducible within individuals, particularly under relative pressures. Whether these differences are attributable to BFR or reflect inherent variability to low-load resistance exercise remains unknown.