Blood Flow Restriction (BFR) training has firmly established itself as a cornerstone intervention in orthopaedic rehabilitation. By utilizing low-load resistance (often 20-30% of 1RM) with partial vascular occlusion, clinicians can facilitate hypertrophy and strength gains comparable to high-load training without the mechanical stress on healing tissues. However, the search for adjunctive therapies to maximize these gains continues. A recent randomized controlled trial (RCT) published in the Journal of the International Society of Sports Nutrition (2026) investigates a novel synergy: BFR combined with dietary nitrate supplementation via beetroot juice (BRJ).
Nitrates and Occlusion: The Physiological Hypothesis
The physiological rationale behind this combination is compelling. BFR training creates a hypoxic environment within the muscle, stimulating metabolic stress. Dietary inorganic nitrates, found abundantly in beetroot juice, are reduced to nitrite and subsequently to nitric oxide (NO) in the body. Importantly, this conversion is enhanced in acidic and hypoxic conditions—exactly the environment created during BFR training. Theoretically, this should improve muscle contractile efficiency and blood flow regulation, potentially mitigating fatigue.
Study Protocol and Dosage
The study, led by Yang et al., recruited 20 male university students and utilized a double-blind, placebo-controlled design. Participants were divided into a BFR-only group and a BFR + BRJ group. The intervention followed a rigorous schedule:
- Supplementation: A one-week pre-load phase followed by continuous supplementation during training. The active group consumed BRJ containing roughly 8 mmol of nitrate per day.
- Training: A four-week program (3 sessions/week) focusing on bilateral knee extension and flexion.
- Parameters: 40% Limb Occlusion Pressure (LOP) and 30% of peak torque load.
Key Findings: Strength vs. Fatigue Performance
Post-intervention analysis revealed that BFR is remarkably effective regardless of supplementation. Both groups demonstrated significant improvements in relative peak torque for knee extensors and flexors at various velocities (60°/s, 180°/s, and MVIC). This reinforces current literature supporting BFR’s efficacy for strength development.
However, the divergence appeared during fatigue testing. While both interventions improved certain metrics of the Countermovement Jump (CMJ), the effects of BRJ were selective. The BFR + BRJ group showed statistically significant improvements in fatigued bilateral CMJ height (p=0.012, d=-1.307), a specific benefit not mirrored to the same extent in the placebo group. Essentially, while raw strength gains were similar, the nitrate-supplemented group maintained better explosive performance under fatigued conditions.
Clinical Implications for Rehabilitation
For the physiotherapist, these findings suggest that beetroot juice is not necessarily a magic bullet for raw strength acquisition in early-stage rehab. However, for late-stage rehabilitation or return-to-sport protocols where fatigue resistance and power maintenance are critical, nitrate supplementation could serve as a valuable ergogenic aid.
If a patient is struggling with maintaining movement quality or power output towards the end of a session, or during return-to-play conditioning, the addition of dietary nitrates might enhance the physiological adaptations of BFR training. As always, clinicians should screen for contraindications before recommending dietary supplements.
References
Yang, X., Lu, Y., Lee, S. K., Xu, H., Chang, H., Liu, Q., & Quan, H. (2026). 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. Journal of the International Society of Sports Nutrition.
