longevity · Outcome
Maximal oxygen uptake. The single strongest mortality predictor in middle-aged adults. Going from 'low' to 'average' fitness cuts all-cause death risk more than quitting smoking.
How to measure: Watch estimates (Apple, Garmin, Whoop) are noisy but trend well. Formal CPET test is the gold standard. Cooper 12-min run or 1.5-mile time is a reasonable home proxy.
Three levers, one stack. Each works through a different mechanism. They compound.
Improves physical performance
300-500 mg nitrate (about 70-140 ml concentrated shot) · 2-3 hours before training or testing
Evidence
Effect size
Research
43 papers
directional · 43 studies · no reliable magnitude
Why: Acts on the demand side (cheaper ATP for the same work) rather than central VO2 capacity. Best ergogenic with a clean safety profile. Pairs well with Zone 2 base building.
See the Beetroot Juice pageImproves physical performance
180-240 min per week at conversational pace · Spread across 3-5 sessions weekly
Evidence
Effect size
Research
113 papers
directional · 113 studies · no reliable magnitude
Evidence pending
150-200 g (roasted, boiled, juiced) · 2-3 hours before training
Evidence
Effect size
Research
None
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Effect size
How big is the change on vo2 max, in the units that matter for this outcome.
Confidence
How sure are we the effect is real for vo2 max, given the studies we have.
For every pick, the “papers” number is how many studies we've cataloged that test this entity for vo2 max. “Favorable” means the study reported the direction you want.
The tier badge (S, A, B…) on the entity itself is its overall research confidence across all outcomes. It's the same letter wherever you see this entity on the site, not specific to vo2 max.
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Why: Zone 2 is what raises ceiling capacity. Without a base, the high-intensity sessions just stress the system without yielding adaptation. Most people skip this and wonder why their VO2max plateaus.
Why: If you want the nitrate effect without buying shots, eating beets a few times a week is enough for chronic adaptation, though not for acute pre-race boost.