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

Abstract

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. 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. 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. 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.