Phosphate supplementation, cardiovascular function, and exercise performance in humans

Abstract

The use of oral phosphate (Pi) supplements to improve muscular work performance has long been proposed without substantiating data. In a double-blind, crossover experiment 11 male runners ingested calcium Pi (176 mmol/day) or placebo for 4 days. On the 3rd treatment day, subjects ran an incremental maximal aerobic capacity test (VO2 max) on a treadmill, and on the 4th day a treadmill run to exhaustion at approximately 70% VO2max. By the 4th day of Pi loading, plasma Pi was significantly higher than control (P less than 0.05); however, erythrocyte Pi, 2,3-diphosphoglycerate, and O2 half-saturation pressure of hemoglobin (P50) were not elevated. VO2 max was not changed by the treatments (mean 62.9, 64.2, 64.9 ml.kg-1.min-1 for control, Pi, and placebo bouts, respectively) nor was submaximal run time to exhaustion (61.6 min for Pi, 65.5 min for placebo). Stroke volume at steady-state VO2 was decreased with Pi (P less than 0.05), whereas cardiac output tended (P = 0.07) to be lower. Greater arteriovenous O2 difference (P less than 0.05) with Pi suggested a peripheral effect that increased O2 extraction. We concluded that in healthy individuals Pi loading produced no improvement in work tolerance or aerobic capacity but did alter some aspects of cardiovascular function.

The Influence of Sodium Phosphate Supplementation on VO2max, Serum 2,3-diphosphoglycerate Level and Heart Rate in Off-road Cyclists

“…Bredle et al (1988), supplemented a group of men with calcium phosphate for 4 days in a dose of 176 mmol/d and registered a significant (p<0.05) increase in blood concentration of inorganic phosphates and improved cardiac output. There were no changes in 2,3-DPG and VO2max values, yet the increased arteriovenous difference in O2 and CO2 concentration suggests a better supply of oxygen to the skeletal and cardiac tissues.…”

Vitamin and Mineral Supplementation to Athletes

“…Kreider and colleagues (80) found higher maximal oxygen uptakes after 4 g phosphatelday but a decrease in 2,3-DPG concentration. No change in 2,3-DPG or improvement in maximal oxygen uptake was observed after 5.7 g phosphatelday ; however, an increase in the arteriovenous oxygen difference was found (14). Duffy and Conlee (39) reported no significant effect of phosphate supplements on endurance, leg power, or oxygen uptake.…”

Effects of sodium phosphate and beetroot juice supplementation on repeated-sprint ability in females

“…Importantly, the mechanisms attributed to improving exercise performance following SP loading relate to both aerobic and anaerobic metabolism (Kreider et al 1992), suggesting that SP loading may benefit prolonged RSA, as is required during a team-game. Specifically, these mechanisms include: increased 2,3-diphosphoglycerate (2,3-DPG) concentration in red blood cells (RBC), resulting in a greater release of oxygen from haemoglobin to the muscle (Benesch and Benesch 1969); enhanced buffering capacity of hydrogen ions (Kreider 1999); improved myocardial efficiency resulting in greater cardiac output and oxygenation of the exercising muscle (Kreider et al 1992); increased adenosine triphosphate (ATP)/phosphocreatine (PCr) resynthesis, due to increased availability of extracellular and intracellular phosphate (Bredle et al 1988;Kreider et al 1992); and enhanced activation of glycolysis and oxidative phosphorylation as a result of increased phosphate availability (Chasiotis 1983).…”