High-Load, Low-Load, and Passive Blood Flow Restriction in Competitive Sprinters

Overview

This randomized clinical trial will include competitive male and female sprinters aged 16-30 years, recruited through purposive sampling. Participants will be randomly assigned to one of three groups: (A) HL-BFR (70-85% 1RM with BFR during sets), (B) LL-BFR (20-30% 1RM with BFR), or (C) Passive BFR (BFR applied between sets). The intervention will consist of a 6-week sprint-specific resistance training program performed thrice weekly, incorporating resisted sprints, barbell step-ups, hip thrusts, Nordic curls, and bounding exercises. Strength will be measured using 1RM testing, explosive power through countermovement and standing broad jumps, and sprint performance via 10m, 30m, and 100m timed sprints. Subjective exertion will be tracked using the sRPE scale. The study aims to determine whether HL-BFR, LL-BFR, or passive BFR produces superior improvements in sprint performance and neuromuscular strength. It is hypothesized that HL-BFR may yield greater adaptations due to combined mechanical and metabolic stress, though LL-BFR and passive BFR may offer practical, low-impact alternatives.

Blood Flow Restriction (BFR) training characterized by applying external pressure to occlude venous return during exercise has gained prominence in both rehabilitation and athletic conditioning due to its ability to stimulate muscle hypertrophy and strength gains with lighter mechanical loads. The physiological basis includes metabolic accumulation, cellular swelling, and increased motor unit recruitment, mimicking high-intensity training effects even with low loads . Elite sprint performance demands a finely tuned combination of explosive strength, neuromuscular power, and sprint-specific endurance across different phases of the race (acceleration, maximal velocity, deceleration). While high-load resistance training (≥ 70% 1RM) has long been the gold standard for developing muscular strength and power , blood flow restriction (BFR) training-particularly in low-load protocols (20-40% 1RM)-has emerged as a low-stress alternative capable of eliciting comparable hypertrophy and strength gains. A growing body of literature now highlights the capacity of both high- and low-load BFR training to improve explosive performance metrics, such as vertical jump, sprint speed, and rate of force development. A systematic review found that athletes undergoing BFR training experienced small to moderate yet significant improvements in jumps (SMD ≈ 0.36), sprints (SMD ≈ 0.54), and power output (SMD ≈ 0.72), surpassing traditional resistance training outcomes. High-load resistance training (≥ 70 % 1RM) is the established standard for enhancing neuromuscular strength and power. Recent investigations have examined adding BFR to high-load protocols (high-load BFR), aiming to amplify metabolic stress and post-activation performance enhancement. Though the evidence is mixed-a systematic review of ≥ 60 % 1RM BFR protocols concluded that only some studies showed additional strength or hypertrophy benefits compared to non-BFR controls emerging data suggest that high-load BFR may offer acute increases in lifting velocity and small improvements in jump and sprint outcomes. Among BFR strategies, low-load BFR (LL-BFR)-typically at 20-40% of one-repetition maximum (1RM)-has the most robust evidence base. Systematic reviews demonstrate that LL-BFR training can induce similar muscle hypertrophy and near-equivalent strength improvements compared to traditional high-load training . These benefits, coupled with lower mechanical stress, have made LL-BFR a preferred method in both clinical and performance settings. Meta-analyses report that while maximum strength gains are slightly lower than high-load training, power, jump, and sprint performance show no significant differences between low-load BFR and high-load resistance training.