Low-load blood flow restricted (BFR) resistance exercise has been suggested to be as effective as moderate and high-load resistance training for increasing muscle size and strength. The purpose of the study was to evaluate the effects of 6 weeks of HL or low-load BFR resistance training on neuromuscular function, strength, and hypertrophy of the knee extensors. Eighteen participants aged 18-22 years old were randomized to one of three training groups: moderate load (ML: 70% of 1 repetition maximum [1-RM]); BFR (20% 1-RM with a vascular restriction set to ~180 mmHg); and a control group (CON) that did not exercise. Participants performed leg extension (LE) and leg press exercises 3 times per week for 6 weeks. Measurements of isometric torque, LE 1-RM, central activation, electrically evoked torque, and muscle volume of the knee extensors were obtained before and after training. Isometric peak torque did not change following the training (p = 0.13). LE 1-RM improved in the ML (34 ± 20%; d = 0.78) and BFR (14 ± 5%; d = 0.67) groups compared to the CON group (0.6 ± 8%; d = 0.09; time x group interaction p = 0.02). Muscle volume increased in the ML (5.6%; d = 0.19) and BFR groups (2.5%; d = 0.09) with no change in the CON group (time x group interaction p = 0.001). There were no changes in central activation and evoked torque in any groups following the training (p > 0.05). Strength and hypertrophy were evident following ML and BFR resistance training programs indicating that both modalities are effective, although ML training appears to be a more potent and efficient. Neuromuscular changes were not evident and warrant more research.
