Beetroot juice supplementation enhances the effects of blood flow restriction training on lower limb strength and vertical jump performance under fatigue in male university students: a randomized, double-blind, placebo-controlled study.

Both BFR and BFR+BRJ interventions significantly increased relative peak torque of knee extensors/flexors at 60°/s.

• Left leg: ppre-post = 0.23, d = -0.89, ηp²Time = 0.775
• Right leg: ppre-post = 0.017, d = -0.63, ηp²Time = 0.744
• Training was performed at 40% limb occlusion pressure and 30% of peak torque load, three times per week for four weeks
• Both groups (n = 10 each) showed improvements, indicating a significant time effect

Both BFR and BFR+BRJ interventions significantly increased relative peak torque of knee extensors/flexors at 180°/s.

• Left leg: ppre-post = 0.028, d = -1.32, ηp²Time = 0.319
• Right leg: ppre-post = 0.007, d = -1.48, ηp²Time = 0.822
• Effect sizes were large (d > 1.0) for both legs
• The ηp²Time for the right leg (0.822) indicated a particularly large time effect

Both BFR and BFR+BRJ interventions significantly increased maximal voluntary isometric contraction (MVIC) torque of knee extensors/flexors.

• Left leg: ppre-post = 0.007, d = -0.11, ηp²Time = 0.825
• Right leg: ppre-post = 0.009, d = -1.31, ηp²Time = 0.842
• Both partial eta-squared values exceeded 0.80, indicating very large time effects
• The right leg showed a notably larger effect size (d = -1.31) compared to the left leg (d = -0.11)

Both interventions significantly improved knee extensor torque during the 100-repetition maximal voluntary contraction fatigue test at 90°/s, for both initial and final repetitions.

• Left leg: ppre-post = 0.029, d = -0.96, ηp²Time = 0.612
• Right leg: ppre-post = 0.007, d = -1.21, ηp²Time = 0.725
• Both initial (first 20 repetitions) and final (last 20 repetitions) torque values were significantly increased
• Improvements in both early and late repetitions suggest enhanced fatigue resistance

Both BFR and BFR+BRJ interventions significantly improved fatigued bilateral countermovement jump (CMJ) height, peak force, and rate of force development (RFD).

• Bilateral CMJ height: ppre-post = 0.048, d = -0.534, ηp²Time = 0.556
• Peak force: ppre-post = 0.047, d = -0.913, ηp²Time = 0.444
• Rate of force development (RFD): ppre-post = 0.044, d = -0.902, ηp²Time = 0.656
• Single-leg CMJ performance showed no significant improvements for either the left or right leg in either group

Post-intervention, only the BFR+BRJ group showed a statistically significant improvement in fatigued bilateral CMJ height.

• BFR+BRJ group fatigued bilateral CMJ height: ppre-post = 0.012, d = -1.307, ηp²Time = 0.846
• This finding was described as 'notable' by the authors, distinguishing the combined intervention from BFR alone
• The effect size was large (d = -1.307) and the partial eta-squared was very large (0.846)
• BRJ supplementation dose was 8 mmol/day of nitrate, preceded by a one-week pre-supplementation phase

The effects of BRJ supplementation were selective rather than broadly superior to BFR training alone.

• BRJ mainly enhanced BFR training by reducing fatigue-related declines in vertical jump performance
• BRJ did not produce broadly superior improvements across all measured strength and performance outcomes
• The study included 20 male university students from the School of Sports, randomly assigned to BFR (n = 10) or BFR+BRJ (n = 10) groups
• The trial was randomized, double-blind, and placebo-controlled

The study design included a one-week BRJ pre-supplementation phase followed by a four-week bilateral knee extensor/flexor BFR training program.

• BRJ supplementation dose: 8 mmol nitrate/day
• BFR training parameters: 40% limb occlusion pressure, 30% of peak torque load
• Training frequency: three sessions per week for four weeks
• Outcomes were assessed using an isokinetic dynamometer (at 60°/s, 180°/s, and MVIC) and a force plate pre- and post-intervention
• Participants were male university students: BFR group age 21.9 ± 1.7 years; BFR+BRJ group age 21.8 ± 1.5 years