Beetroot VO2max endurance sports: what nitrates do during exercise

Beetroot and VO2max endurance sports are inextricably linked by one molecule: nitrate. Research shows that inorganic nitrate from beetroot improves oxygen efficiency during efforts lasting 3 to 10 minutes. Here's what the science says.

What is nitrate and why are endurance athletes interested in it?

Nitrate (NO3−) is an inorganic compound naturally found in vegetables, with beetroot being the richest dietary source. A standard 500ml serving of beetroot juice contains an average of 400 to 500mg of nitrate. In the body, nitrate is converted to nitrite (NO2−) via the salivary glands, and then to nitric oxide (NO). The latter substance is functionally relevant for the performing athlete.

Nitric oxide is a vasodilator. It lowers peripheral resistance in blood vessels and improves blood flow to active muscle tissue. More specifically, it influences the efficiency of mitochondria: the same work requires less oxygen. For endurance athletes, this means a direct link to VO2max and oxygen-sparing exercise efficiency.

The mechanism is well-documented. Studies show that nitrate supplementation can reduce the oxygen cost of submaximal exercise by 3 to 5 percent. That's a small but measurable number — and in cycling or trail running, every percentage counts.

How does beetroot affect VO2max in endurance athletes in practice?

VO2max is the maximum amount of oxygen an athlete can take in and use per minute, expressed in milliliters per kilogram of body weight per minute (ml/kg/min). Elite cyclists achieve values of 70 to 85 ml/kg/min. Trail runners and triathletes score similarly.

Nitrate from beetroot works on two levels. Firstly, it improves oxygen efficiency at submaximal intensities — the classic "economy effect." Secondly, there is evidence, particularly from umbrella reviews such as those published in June 2025, that nitrate can also slightly increase VO2max itself in trained athletes. The latter is the strongest signal that research provides to date.

The effect is most clearly measurable during exercise durations of 3 to 10 minutes — the zone where oxygen transport and mitochondrial efficiency are crucial for performance. In that zone, the oxygen spectrum is not yet fully saturated, and nitrate-induced vasodilation plays its biggest role.

During efforts longer than 60 minutes, where glycogen depletion and carbohydrate intake become the limiting factor, the relative importance of nitrate decreases. Carbohydrate delivery then becomes the priority.

When is the effect of nitrate on VO2max greatest?

Timing and dose are crucial. Most studies use an acute supplementation of 400 to 500mg of nitrate, administered 2 to 3 hours before exercise. Chronic supplementation over 3 to 6 days yields similar or slightly stronger effects. The nitrite peak in the blood occurs 2 to 3 hours after intake.

Oral hygiene is an underestimated variable. Antiseptic mouthwashes eliminate the nitrate-reducing bacteria in the oral cavity, thereby blocking the conversion of nitrate to nitrite. Brushing teeth with antibacterial toothpaste just before supplementation significantly reduces the effect.

Training status also plays a role. In untrained individuals, the effect is greater than in trained athletes — presumably because trained athletes already have more efficient mitochondrial function. Nevertheless, recent umbrella reviews show consistent effects, also in recreational and trained endurance athletes in cycling and trail running.

What does nitrate mean for cycling and trail running specifically?

In cycling, climbing segments of 4 to 8 minutes are the most relevant scenario. Here, the power-to-oxygen uptake ratio directly determines speed. A 3 percent reduction in oxygen cost translates to a measurable time difference on an 8-minute climb.

In trail running, relevant effort blocks occur on steep climbs lasting 3 to 12 minutes. VO2max is a stronger predictor of performance in trail runners than in flat running, because terrain variation constantly shifts between high and low intensity. Nitrate plays its best role in peak intensity blocks.

For triathletes, similar logic applies during the bike segment and the early running phase. Nitrate is not a magic solution, but a precision tool for high-intensity, short to medium-duration efforts.

Nitrate and carbohydrates: two separate mechanisms

Nitrate and carbohydrates work through entirely different physiological pathways. Nitrate improves oxygen efficiency. Carbohydrates provide the fuel itself: glucose and fructose are oxidatively burned to produce ATP.

The recommendation of 60 to 90 grams of carbohydrates per hour for exercise longer than 60 minutes applies regardless of nitrate supplementation. The 2:1 glucose/fructose ratio — as used in the Eagle Nutrition fruit performance bar — maximizes the intestinal absorption rate via two separate transporters: SGLT1 for glucose and GLUT5 for fructose. This is a mechanism entirely separate from nitrate metabolism.

A 25-gram fruit performance bar provides 20 grams of carbohydrates in the 2:1 ratio. This is clean fuel without artificials, for exercise where glycogen delivery is the limiting factor. Nitrate does not solve that problem. Carbohydrates do.

The two ingredients are complementary, not competing. Nitrate optimizes the engine. Carbohydrates provide the fuel. Understanding both mechanisms builds a more targeted strategy.

Is nitrate in the Eagle fruit performance bar?

No. The Eagle Nutrition fruit performance bar contains no added nitrate or beetroot juice. The formula is built around 2:1 glucose/fructose carbohydrates, fruit as the primary ingredient source, and a clean label without artificials.

Nitrate is a pre-workout supplementation strategy that you separate from fuel during exercise. The Eagle fruit performance bar is functional for during the ride, run, or race — not as a nitrate source. Both strategies have their own timing and their own purpose.

What the fruit performance bar and nitrate share is the philosophy of clean, functional input without unnecessary additives. No artificials. No overclaims. Verifiable efficacy through known mechanisms.

What does the science say about beetroot and VO2max summarized?

The evidence for nitrate from beetroot as a performance ingredient in endurance sports is consistent and growing. An umbrella review published in June 2025 confirms the signal: nitrate improves oxygen efficiency and has measurable effects on VO2max, particularly during 3 to 10-minute high-intensity efforts. The effect is strongest in cyclists and runners working at 80 to 95 percent of their VO2max.

The mechanism is biologically plausible, reproducible under laboratory conditions, and relevant for field situations. The optimal dose is between 400 and 500mg of nitrate, ingested 2 to 3 hours before exercise. Chronic intake over several days enhances the effect.

Nitrate is not a substitute for training adaptation, nutrition strategy, or recovery. It is a precision tool with a specific application window. Use it targeted or not at all.