Acute Physiological and Perceptual Responses to Low-Load Blood Flow Restriction versus High-Load Resistance Exercise: A Randomized Crossover Pilot Study

Abstract

Objective: To compare the acute physiological and perceptual responses to low-load blood flow restriction (LL-BFR) resistance exercise and traditional high-load (HL) resistance exercise in healthy males. Methods: In a randomized crossover design, nine healthy males performed bilateral knee extensions under two conditions: LL-BFR (30% 1RM with blood flow restriction) and HL (80% 1RM without restriction). Each protocol involved three sets of eight repetitions. Growth hormone (GH), creatine kinase (CK), blood lactate, systolic and diastolic blood pressure (SBP, DBP), and rate of perceived exertion (RPE) were measured at rest, during, and after exercise. Data were analyzed using two-way repeated-measures ANOVA. Results: GH increased significantly after LL-BFR (p < 0.0001), but not after HL (p > 0.05). CK increased only after HL at 48 h (p = 0.0034). Blood lactate was higher across sets in HL (p < 0.05). RPE increased similarly in both trials (p > 0.70). SBP increased during both protocols (p < 0.001), while DBP was higher in LL-BFR, particularly after Set 3 (p = 0.0275). Conclusion: LL-BFR induces a greater endocrine response with less muscle damage than HL exercise but increases vascular stress. It may serve as a practical alternative where high loads are contraindicated.