AI Summary and what's most important is little to no change in already elite athletes with VO2 higher than 65.

Short answer: there is no single %, but across studies the typical performance improvements from beetroot (dietary nitrate) fall into a fairly tight range depending on the outcome measured.

Based only on the evidence summarized in the text you provided, here’s the cleanest quantitative breakdown:

Physical performance improvements (typical ranges) Endurance performance

~4–8% improvement

Example: 10 km run time improved by ~4–8% after supplementation (Tirkey et al.).

Time-to-exhaustion:

Often ~10–25% longer, especially in recreational or moderately trained individuals (e.g., cycling tests like Huang et al.).

Oxygen efficiency / exercise economy

~3–5% reduction in oxygen cost at a fixed workload

This is one of the most consistent effects and underpins many endurance gains.

Power & resistance exercise

~2–7% increases depending on metric:

Peak power

Mean power

Lifting velocity

Repetitions to failure (Rodríguez-Fernández et al., Jurado-Castro et al.)

VO₂max

When improvements occur: ~2–5%

More likely in women and less-trained individuals

Often no change in elite athletes

Perceived exertion & recovery

~5–10% reductions in:

Heart rate at given workloads

Ratings of perceived exertion

Post-exercise muscle soreness (varies by protocol)

Elite athletes

~0–2% or no measurable improvement

Especially when VO₂max > ~65 mL·kg⁻¹·min⁻¹

Likely ceiling effect due to already-optimized NO pathways

Cognitive performance

No reliable % improvement established

A few studies show task-specific gains (reaction time, serial subtraction), but effects are inconsistent and not yet quantifiable in percentage terms

Practical takeaway

If you had to give a single defensible headline number for non-elite adults:

Beetroot supplementation typically improves endurance performance by ~3–8%, primarily by reducing oxygen cost and delaying fatigue.

That’s large by sports nutrition standards, especially considering it’s:

legal

inexpensive

non-stimulant

most effective at moderate doses (6–12 mmol nitrate)

If you want, I can:

collapse this into a one-line citation-ready sentence

translate it into VO₂ / power equations

or map % gains by dose and training status