Can beetroot juice boost recovery from exercise? Original paper

Strenuous exercise causes muscle damage and fatigue, and proper recovery from exercise is essential for optimizing physical performance. Several dietary supplements have been shown to improve athletic performance, but less is known about the effect of ergogenic (performance-enhancing) supplements on recovery from exercise.

Nitrates — bioactive compounds found in beetroot juice — are metabolized by the body into nitric oxide (NO). NO has important cardiovascular functions that include promoting vasodilation and enhancing blood flow and oxygen delivery to muscles. NO may also have anti-inflammatory properties.^[1] These effects make nitrates an attractive supplement for athletes. Although nitrates are known to improve performance during endurance, strength, and explosive exercise,^[2][3][4] a comprehensive study was needed on the effects of nitrates on exercise recovery.

This systematic review synthesized the available evidence on the effects of nitrates on exercise recovery and exercise-related fatigue.

A total of 15 randomized controlled trials were included in the review, including 327 total participants (93% men, 7% women). The participants included runners, triathletes, military personnel, football players, cyclists, and healthy active adults. Acute (short-term) and chronic (longer-term) supplementation protocols were used, with studies lasting 2–24 hours (for acute studies) and 1–9 weeks (for chronic studies).

The outcomes assessed were recovery variables (including the blood metabolites glycerol, arabitol, xylose, 𝛼-oleoylglycerol), strength and power (maximal voluntary isometric contraction, countermovement jump), cardiovascular metrics (blood pressure, heart rate, VO₂), muscle damage (creatine kinase, lactate dehydrogenase), inflammation (IL-6, IL-8, C-reactive protein, reactive oxygen species), and pain and effort perception (delayed-onset muscle soreness or DOMS, pain pressure threshold). The study outcomes were measured at various time points before and after exercise.

Nine of the studies (60%) noted an improvement in some measure of recovery after supplementation with nitrate.

Overall, supplementation with nitrate improved the recovery of countermovement jump and maximal voluntary isometric contraction performance, reduced DOMS, enhanced the pain pressure threshold and reduced pain/effort perception, increased antioxidant capacity, and improved the recovery of heart rate, blood pressure, and VO₂ after exercise. Nitrates provided the greatest recovery benefit after anaerobic activities including drop jumps and repeated sprints, whereas it didn’t significantly affect recovery after running a marathon. Markers of inflammation were not affected.

An acute dose of 12–20 mmol and a chronic daily dose of 3.5–12 mmol were recommended to enhance recovery from exercise based on the available evidence.

There were large differences in the study designs, the types of exercise, the participants, the nitrate dosage, and the timing of supplementation across the studies included in this review. Additionally, the authors were unable to conduct a statistical analysis (i.e., a meta-analysis). For these reasons, it’s difficult to draw a definitive conclusion about the effects of supplementation with nitrate on exercise recovery.