Bayesian Comparison of Low-Load Blood Flow Restriction and High-Load Resistance Exercise on Biceps Brachii Muscle Hypertrophy in Untrained Men

This study was designed to examine the efficacy of low-load blood flow restriction resistance exercise (BFR-RE) performed to voluntary failure compared with traditional high-load resistance exercise (HL-RE) in inducing muscular adaptations in untrained individuals. The experimental framework was structured to isolate the effects of mechanical load and metabolic stress by standardizing the selection of exercises and the training frequency across groups.

A controlled, single-blind, repeated-measures design was used, with participants allocated to BFR-RE, HL-RE, or a non-exercising control condition. The intervention period was set at 8 weeks to ensure sufficient exposure for hypertrophic and neuromuscular adaptations, while minimizing potential confounding effects of long-term training variability.

The BFR-RE protocol was developed to emphasize metabolic stress through low external loading (30% 1RM), partial vascular occlusion (60% limb occlusion pressure), and sets performed to volitional failure. In contrast, the HL-RE condition was structured to prioritize mechanical tension using moderate-to-high loading (70% 1RM) without vascular restriction. This contrast enables a mechanistic comparison of two distinct hypertrophic stimuli.

To reduce acute exercise-induced confounding factors, particularly transient muscle swelling, post-intervention assessments were complemented with a delayed follow-up measurement. This approach was incorporated better to reflect true morphological adaptations rather than short-term physiological responses.

The methodological approach integrates imaging-based and performance-based assessments to capture both structural and functional adaptations. The overall design enables evaluation of whether BFR-RE can provide a time-efficient and lower-load alternative to traditional resistance training while maintaining comparable adaptive outcomes.