Limited evidencePhysical performance

Sodium Phosphate

Phosphate loading before competition, an old idea with a stubbornly inconsistent literature. Some trials show aerobic gains, others show nothing at all.

Evidence last reviewed: August 2026

What the science says

Aerobic capacity gains in some trials Limited evidence
A randomised, placebo-controlled crossover study in cyclists found short-term phosphate loading improved aerobic capacity under acute hypoxia, with related work reporting changes in cardiorespiratory responses. Results in normoxia have been less consistent.
No effect on time-trial performance in others Limited evidence
A randomised trial found sodium phosphate did not improve 20 km cycling time-trial performance or the main physiological responses to submaximal exercise.
Repeated-sprint results are mixed Limited evidence
Randomised trials of phosphate loading for repeated-sprint ability, alone or combined with other ergogenic aids, produced small and inconsistent effects.

Dosage & safety

Studied doseLoading protocols use about 3–4 g/day of sodium phosphate split into four doses for 3–6 days before competition, with several weeks of washout between loads.

SafetyGI upset is common. High phosphate intake is genuinely risky in kidney disease and can disturb calcium balance, so repeated loading is not advised. It also adds a meaningful sodium load.

Scientific references

Effects of Short-Term Phosphate Loading on Aerobic Capacity under Acute Hypoxia in Cyclists: A Randomized, Placebo-Controlled, Crossover Study
Płoszczyca K, Chalimoniuk M, Przybylska I — Nutrients, 2022
The Effects of Sodium Phosphate Supplementation on Physiological Responses to Submaximal Exercise and 20 km Cycling Time-Trial Performance
Brown JA, Glaister M — J Diet Suppl, 2019
Effects of sodium phosphate and beetroot juice supplementation on repeated-sprint ability in females
Buck CL, Henry T, Guelfi K — Eur J Appl Physiol, 2015

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