Effects of sodium phosphate and caffeine ingestion on repeated-sprint ability in male athletes

Practical Issues in Evidence-Based Use of Performance Supplements: Supplement Interactions, Repeated Use and Individual Responses

“…While the former may simply be a quirk of the statistical analysis in a small sample size, there may be some interaction that requires further investigation. Similar findings regarding the combination of caffeine and phosphate [42, 43] also merit additional research.…”

“…Trend to better sprint times with combined compared with placebo (~2% improvement) suggesting some lessening of the effect of phosphate when combined with nitrate. Effects of phosphate seen when fresh as well as fatiguedCaffeine and phosphate Kopec et al [42]Trained team sport athletes ( n  = 11 M)Crossover design to produce caffeine, phosphate, combined, and placebo trials6 mg/kg caffeine @ 60 min pre-exercise and/or 6 days @ 50 mg/kg/dayFFM sodium phosphate in split dosesWashout of 17 days between trialsTeam sport 6 × 20 s sprints Undertaken @ 0, 30, and 60 around a 2 × 30 min simulated team game circuitCaffeine: NoPhosphate: PerhapsInteraction: independent mechanism with possibly counteractive effectAlthough results failed to reach statistical significance, effect size and magnitude based analysis revealed that, compared with placebo, phosphate resulted in the fastest times for all sprints with moderate-large effect sizes and “likely” to “very likely” benefits. The beneficial effects of combined were smaller, and the effects of caffeine alone were minimal Buck et al [43]Recreationally trained team sport athletes ( n  = 12 F)Crossover design to produce caffeine), phosphate, combined, and placebo trials6 mg/kg caffeine @ 60 min pre-exerciseand/or 6 days @ 50 mg/kg/day FFM sodium phosphate in split dosesWashout of 17 days between trialsTeam sport 6 × 20 s sprints Undertaken @ 0, 30, and 60 around a 4 × 15 min simulated team game circuitCaffeine: NoPhosphate: YesInteraction: independent mechanism with no additive effectOverall results showed that combined and phosphate alone improved sprint times when fresh (set 1) and fatiguing (set 2 and 3) compared with placebo.…”

The Effects of Sodium Phosphate Supplementation on Physiological Responses to Submaximal Exercise and 20 km Cycling Time-Trial Performance

“…is that SP supplementation may not increase 2, 3-DPG concentration in red blood cells. Indeed, of those studies that have measured 2, 3-DPG concentrations following SP supplementation, Cade et al (1984) and Stewart et al (1990) reported significant increases, Buck et al (2015), Czuba et al (2008), Kopec et al (2016), and Kreider et al (1992) reported no change, and Kreider et al (1990) reported a significant decrease. Once again, the use of a small sample sizes may have influenced these findings along with the fact that erythrocyte 2, 3-DPG levels are already elevated in endurance trained individuals (Brodthagen et al, 1985;Buck et al, 2013) and can change rapidly post-sampling (Llohn et al, 2005).…”

“…Nevertheless, relative to placebo, the present study demonstrated no SP-induced increase in resting serum phosphate concentration. Apart from one exception (Czuba et al, 2009), previous research has also reported no change in serum phosphate concentration following SP supplementation (Brewer et al, 2013;Buck etal., 2015;Kopec et al, 2016;Kreider et al, 1990;Stewart et al, 1990). Given similarities in the dosing strategies used in these investigations, it seems, as highlighted by others (Buck et al, 2015;Kopec et al, 2016;Kreider et al, 1992;Stewart et al, 1990), that the measure may not be the best indicator of SP loading effects.…”

“…Sodium phosphate (SP) is a legal nutritional supplement that has been suggested to improve athletic performance (Currell et al, 2012). Several mechanisms have been proposed to explain this potential ergogenic effect, including an increase in resting erythrocyte 2, 3-diphosphoglycerate (2, 3-DPG) concentration (promoting oxygen offloading at the muscle via a reduction in oxyhaemoglobin affinity) (Bremner et al, 2002;Cade et al, 1984), an enhancement of myocardial contractility (Kreider et al, 1992), an increase in extracellular hydrogen phosphate (HPO4 -) concentration (facilitating hydrogen ion buffering) (Buck et al, 2015;Kopec et al, 2016), and an increase in the activity of various oxidative enzymes, such as phosphofructokinase and glyceraldehyde 3-phosphate dehydrogenase (Buck et al, 2013).…”