Benefits of 6-weeks high-intensity circuit training with or without blood flow restriction on physical fitness in active males: A randomized controlled trial.

To investigate the effects of a 6-weeks 7-min workout (7 MW), with and without blood flow restriction (BFR), on physical fitness. Thirty-three active healthy males (age: 23.3 ± 2.6 yr; body mass index: 22.5 ± 1.9 kg m-2) were randomly assigned to 7 MW, 7 MW-BFR (150 mmHg cuff pressure applied to proximal thighs), or control (CON) groups. 7 MW, comprising 12 bodyweight exercises, was performed 3 times per week, with one set during weeks 1-3 and two sets during weeks 4-6. Outcomes included body fat percentage (%BF), thigh circumference (TC), maximal oxygen uptake (VO2max), isometric mid-thigh pull variables (peak [PF] and mean [MF] force, and maximal rate of force development [RFDmax]), and countermovement jump (CMJ) height. Adjusting for baseline values, post-intervention VO2max was higher in 7 MW (p < 0.001, 95% CI: 2.1-5.7 mL kg-1·min-1) and 7 MW-BFR (p = 0.002, 95% CI: 1.3-4.9 mL kg-1·min-1) than in CON. PF and MF were greater in both training groups than in CON, with larger effects in 7 MW-BFR (PF: p < 0.001, d = 1.21, 95% CI: 155-451 N; MF: p < 0.001, d = 1.15, 95% CI: 142-448 N) than in 7 MW (PF: p = 0.030, d = 0.63, 95% CI: 17-315 N; MF: p = 0.026, d = 0.68, 95% CI: 23-332 N). No significant changes were observed in %BF, TC, RFDmax, or CMJ height. The 7 MW-based program can improve aerobic capacity and muscular strength in active males, and BFR may further augment strength gains.