Sodium phosphate C
Results are contradictory: one study showed an effect, the second did not
Citable fact
«Sodium phosphate» — evidence level C. Dosage: Loading regimen: 1 g of sodium phosphate (or the equivalent of about 3–4 g of salt) 4 times a day for 3–6 days before competition; or 3–4 g per day in a course of 3–6 days. A single dose gives no effect. Source: PMID 17569583, permanent link to the source in the list below.
How it works
Phosphate loading is based on several proposed mechanisms: an increase in the concentration of 2,3-diphosphoglycerate in erythrocytes, which facilitates oxygen release to tissues; an increase in the buffer capacity of the blood; a possible improvement in mitochondrial function and myocardial contractile function. Phosphate also participates in energy metabolism as a component of ATP and creatine phosphate. The regimen is a loading one, over several days before competition, since the effect is related to a gradual change in blood composition rather than to a single dose.
Dosage and intake
Loading regimen: 1 g of sodium phosphate (or the equivalent of about 3–4 g of salt) 4 times a day for 3–6 days before competition; or 3–4 g per day in a course of 3–6 days. A single dose gives no effect
Loading regimen: in divided doses over 3–6 days before competition, with the last dose a day before the start. Intake on the day of competition makes no sense
Forms
Sodium phosphate powder or capsules, often as a mixture of monobasic and dibasic phosphate. Requires precise weighing; the taste is salty and unpleasant
What is confirmed
- In one study it improved time trial cycling performance in trained athletes
- Theoretically improves oxygen release to tissues through an increase in 2,3-diphosphoglycerate
- May increase the buffer capacity of the blood
Adverse effects and limitations
- The results are contradictory: one study showed improvement, another in a 30-km race in trained cyclists showed no effect
- Not suitable for people with kidney disease, heart failure and hypertension: the loading regimen provides a lot of sodium and may raise blood pressure
- The practical value is questionable because of the unpredictability of the effect, and data on the safety of loading regimens are limited
Interactions
- With diuretics, ACE inhibitors and potassium-sparing diuretics — risk of electrolyte imbalance and hyperkalemia
- With antacids and phosphate-binding drugs — reduced absorption
- With antihypertensive drugs — the effect of the sodium load on their effectiveness
Who must not use it
- Under 18 years: There are no studies in children and adolescents; not recommended
- Pregnancy and lactation: Loading doses in pregnancy and lactation have not been studied; contraindicated
- Chronic kidney disease — contraindicated
- Heart failure and hypertension — contraindicated
- Hyperphosphatemia and disorders of phosphorus-calcium metabolism — contraindicated
- Tendency to edema — not recommended
- Diuretic use — only as prescribed by a doctor
Sources
- Sodium phosphate loading improves laboratory cycling time-trial performance in trained cyclists · Folland JP, Stern R, Brickley G · Journal of science and medicine in sport, 2008 · PMID 17569583
- Phosphate Loading Does not Improve 30-km Cycling Time-Trial Performance in Trained Cyclists · Pope H, Davis M, Delgado-Charro MB · International journal of sport nutrition and exercise metabolism, 2023 · PMID 37087103
See also
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