Repeated sodium phosphate loading and cycling performance
What it found
In 9 trained male cyclists, two rounds of sodium phosphate loading led to higher peak oxygen uptake than placebo, and possibly better time-trial performance.
What they found
Studies in people
Peak oxygen uptake
Peak oxygen uptake was 3.5 to 4.3 percent higher after the first sodium phosphate phase and 7.1 to 7.7 percent higher after the second, compared with baseline and placebo.
Time-trial performance
Time-trial times were about 60 to 70 seconds shorter after both sodium phosphate phases, but the effect sizes and smallest-worthwhile-change values did not differ from baseline and placebo.
Power output
Mean power output was greater than placebo at the 250-kJ and 500-kJ points during the time trial after the second sodium phosphate phase.
What the authors conclude
“In summary, repeated SP supplementation, ingested either 15 or 35 d after initial loading, can have an additive effect on VO2peak and possibly time-trial performance.”
Also in their conclusions
- They conclude that repeated sodium phosphate supplementation, taken either 15 or 35 days after initial loading, can have an additive effect on peak oxygen uptake and possibly time-trial performance.
How it was done
Research into sodium phosphate supplements had not looked at what happens when the supplement is taken again in a second phase.
Nine trained male cyclists did baseline time-trial and peak oxygen uptake tests, then took either 50 mg per kg of fat-free mass per day of tribasic sodium phosphate or a placebo for 6 days before repeating the tests. They completed two sodium phosphate phases and one placebo phase, with a 14-day washout between phases.
What it can’t tell you
- We summarised it from the abstract only.
- This was a small study of 9 trained male cyclists, so the results may not apply to other people.
- The time-trial performance differences were not clearly separated from placebo, so it is uncertain whether the supplement truly improves race times.
Who paid
- Authors work at
- University of Western Australia, Australia
The paper
- Title
- Effect of repeated sodium phosphate loading on cycling time-trial performance and VO2peak
- Type
- Study
- Evidence
- Studies in people
- Summarised from
- Abstract only
- Cite
- Brewer CP, Dawson B, Wallman KE, Guelfi KJ (2013). Effect of repeated sodium phosphate loading on cycling time-trial performance and VO2peak. International journal of sport nutrition and exercise metabolism. doi:10.1123/ijsnem.23.2.187PubMed 23114686DOI
Summary written 26 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error