How we rate
“Strong” = several concordant meta-analyses or systematic reviews. “Moderate” = one synthesis, or several controlled trials. “Limited” = early trials only. The rating is about the quality of the studies, not about how useful the supplement is.
Sodium phosphate
Taken 3 to 6 days before exercise, sodium phosphate improved VO2max and time trial performance in small trials. More recent time trial trials show no effect.
Benefits
- Time trial: in trained cyclists, 1 g four times a day for 6 days increased average power by 9.8% and shortened a 16.1 km time trial by 3%.
- VO2max: in trained cyclists, VO2peak increased by 3.5 to 4.3% after a loading phase, then by 7.1 to 7.7% after a second one.
- In 7 runners, VO2max increased from 4.77 to 5.18 L/min and the anaerobic threshold rose, without a significantly better time over 5 miles.
- Repeated sprints: in thirteen female team sport players, total sprint time was faster than with a placebo or beet juice; same result in twelve other players.
- In hypoxia: in 20 cyclists, lower heart rate and greater stroke volume at low to moderate intensity.
Precautions
Tolerance: the study summaries in this profile do not describe adverse effects, and the loading phases last only a few days: nothing on prolonged intake. Limitations: time trials: nothing over 20 km (20 cyclists), over 30 km (16 cyclists), nor in 100 and 250 kJ events, 1 or 8 days after loading. In female cyclists, neither 25, 50, nor 75 mg/kg per day improved the time trial. In hypoxia: no aerobic capacity gain in 24 cyclists, only 3 to 5% in a few responders. In trained athletes, 6 days of loading changed neither VO2peak nor energy intake; a commercial product changed neither endurance nor power in 11 men. In eleven team sport players, the gain on repeated sprints was not significant. Reviews consider the results inconsistent (dose, type of effort, fitness level of athletes).
Recommended dosage
50 mg per kg of lean mass per day (or 1 g four times a day), for 3 to 6 days before the event.
How to take it
- For whom: trials involve trained cyclists, runners, and team sport players. None involve weight training.
- Dose: 50 mg per kg of lean mass per day in most trials; in cyclists, 25 and 75 mg/kg did not perform better.
- Duration: a loading phase of 3 to 6 days; in one trial, a second phase further increased VO2peak.
- Form: tribasic sodium phosphate orally, dibasic in one trial (3.5 g per day for 4 days).
- What does not work: on 20 and 30 km time trials in trained cyclists, no gain.
- With caffeine: in twelve female players, phosphate taken with caffeine also improved repeated sprints.
Did you know?
In 7 runners, VO2max increased significantly after 6 days of sodium phosphate, but their 5-mile time did not change significantly.
What the studies say
This study examined the effects of a 6-day sodium phosphate supplementation (50 mg/kg of fat-free mass/day) on aerobic capacity in hypoxia in 24 trained male cyclists. Overall, aerobic capacity in hypoxia was not improved by supplementation. However, high individual variability was observed, with certain individuals (responders) showing a 3% to 5% increase in performance. The study concludes that sodium phosphate is not a generalized ergogenic aid for aerobic capacity in hypoxia, but could benefit certain athletes.
Płoszczyca K, Chalimoniuk M, Przybylska I, Czuba M. — Nutrients (2022) — View the source study
Pairs well with
For information only: not a substitute for medical advice. Dietary supplements are not a replacement for a varied, balanced diet. Learn more