You’ve seen it at race expos. You’ve probably scrolled past it in training group chats. Someone always shows up to the pre-race hotel breakfast with a small dark bottle of something that looks like it came from a crime scene. Beetroot juice has been a fixture in endurance sport nutrition for over a decade now, and the hype around it has only grown. But OCR isn’t a road marathon. It’s a sport where you run six to twenty miles, haul yourself over walls, dangle from rigs, and drag sandbags up hills. Does the nitrate advantage that works in clean endurance contexts actually translate to this kind of mixed-modal chaos?
The short answer is: probably yes, with important caveats. The longer answer is worth understanding before you start drinking beet shots two hours before your next Spartan Beast.
What Nitrates Actually Do
The mechanism behind beetroot juice isn’t mysterious. Beetroots are extremely high in dietary nitrates — inorganic compounds that the body converts, via a pathway involving oral bacteria and stomach acid, into nitric oxide. Nitric oxide is a vasodilator: it widens blood vessels, reduces the oxygen cost of exercise, and improves the efficiency of mitochondrial function in muscle cells.
In practical terms, this means your muscles can do the same amount of work for less oxygen. That’s a meaningful advantage in any endurance context, and it’s why beetroot juice and concentrated nitrate shots became popular with distance runners and cyclists well before they made inroads in strength or power sports.
The research base here is solid. Peer-reviewed studies have repeatedly demonstrated that dietary nitrate supplementation reduces the oxygen cost of submaximal exercise — sometimes by as much as three to five percent. For trained endurance athletes, that’s a real performance delta. It’s not a magic supplement, but it’s one of the few legal ergogenic aids that has genuinely consistent research support behind it.
The OCR-Specific Question
Here’s where it gets more nuanced. Most of the landmark nitrate research was conducted in steady-state endurance conditions — cycling at a fixed intensity, treadmill running at a set pace. OCR is nothing like that. The metabolic demands of an obstacle course race are highly variable: you’re running, climbing, carrying, crawling, jumping, and hanging, often within the same mile. Heart rate spikes and drops constantly. You’re working across multiple energy systems inside a single event.
The question researchers have increasingly turned to is whether nitrate’s efficiency benefit holds up under intermittent, high-intensity, or mixed-modal conditions. The evidence here is more mixed but still directionally positive. Studies on intermittent sprint protocols — which are structurally closer to OCR than steady-state endurance tests — have shown meaningful nitrate benefits for effort sustainability, with some evidence of reduced recovery time between high-intensity bouts. That matters in OCR: the ability to push hard on a trail section, recover while you queue at an obstacle, and push hard again is exactly the physiological demand the sport makes.
There’s also emerging work on nitrate’s role in muscle contractile efficiency — the ability of muscles to generate force without proportionally greater oxygen demand. For obstacle athletes, this is relevant at the grip and upper-body level, where the fatigue profile is different from a pure runner’s. Grip endurance and lat/shoulder fatigue are late-race limiting factors for most competitive OCR athletes. If nitrates offer even a marginal improvement in muscular efficiency at those sites, the cumulative benefit across a three-hour Beast could be meaningful.
The Skeptic’s Case
None of this means you should build your race-day nutrition strategy around beet shots and expect a transformation. A few important limitations deserve honest attention.
First, the magnitude of effect in trained athletes is smaller than in recreational ones. The efficiency gains from dietary nitrates are most pronounced in people who aren’t already highly trained, because trained athletes have more efficient cardiovascular and muscular systems to begin with. If you’re a competitive OCR athlete with years of structured training, the bump from nitrate loading may be smaller than the studies suggest for general populations.
Second, the oral bacteria pathway matters. Dietary nitrates require specific bacteria in your mouth to begin the conversion process. Antibacterial mouthwash — which many athletes use — can significantly blunt the nitrate effect by killing the very bacteria responsible for conversion. If you’re using antibacterial mouthwash in the days before a race, you may be canceling the benefit before it starts.
Third, individual response varies. Some athletes are non-responders to nitrate supplementation for reasons that aren’t fully understood. Genetics, baseline nitrate intake from diet, and gut microbiome composition all appear to influence response. The only way to know where you fall is to test it in training, not on race day.
Finally, the research is thinner on ultra-distance and multi-hour events than on shorter efforts. Most beetroot juice studies run for ninety minutes to three hours. A full Spartan Ultra or a multi-lap competitive format pushes beyond that window, and the evidence for sustained nitrate benefit over very long durations is less robust.
Practical Protocol: If You’re Going to Use It
The research suggests a few consistent principles for athletes who want to experiment with beetroot juice or concentrated nitrate shots.
Timing matters. Peak nitrate conversion to nitric oxide occurs roughly two to three hours after ingestion. Consuming your beet shot thirty minutes before a race is too late for full effect. Aim for two to two-and-a-half hours pre-race. Some athletes loading for multi-day events use a three-to-five day loading protocol, consuming nitrates daily in the days leading up to the event to build systemic levels.
Dose matters too. Most of the research showing performance effects used doses equivalent to roughly 400–500mg of inorganic nitrate — the amount found in approximately 500ml of beetroot juice or a standard concentrated shot (the small 70ml bottles widely available in sports nutrition retail). Eating a couple of roasted beets the night before a race is not the same thing, nutritional theater aside.
Avoid antibacterial mouthwash for at least 24 hours before and on race morning. Use regular fluoride toothpaste if you need to brush. Don’t rinse with anything antibacterial until well after your race window.
And test in training first. Race day is not the time to discover that beetroot juice causes you significant GI distress — which it does for a meaningful subset of athletes, particularly at higher doses. A stomach issue at mile four of a Beast is its own kind of penalty.
The Bottom Line
Beetroot juice is one of the most research-supported legal performance aids available to endurance athletes, and OCR athletes have genuine reason to consider it. The nitrate-to-nitric-oxide pathway is real, the efficiency gains are documented, and the emerging evidence on intermittent and mixed-modal performance is promising enough to take seriously.
It is not, however, a miracle protocol. The gains are modest, individual response varies, and the practical details — timing, dose, mouthwash avoidance — matter more than most athletes realize when they grab a beet shot at the expo tent twenty minutes before the gun goes off.
Use it properly or don’t expect much. Test it in training. Nail the timing. Skip the antibacterial rinse. Then go race — the beets can handle the rest.