The Impact Of Sodium Phosphate Supplementation In Trained Vs Untrained Females: A Pilot Study

Sodium phosphate (SP) has been shown to improve aerobic capacity, however studies in females are limited. PURPOSE: This study explored the impact of SP supplementation on an 800 m time-trial (TT) in trained female middle-distance runners (TF) vs untrained females (UTF). We hypothesized that SP would improve TT performance more in UTF vs TF. METHODS: Ten females (3 T, 7 UTF) completed this placebo-controlled, single-blind study. Body composition and fat-free mass (FFM) were assessed for accurate SP dosing via bioelectric impedance, after which a baseline all-out 800 m TT was completed. Participants were randomized to receive either SP or Placebo (P), 4 times/day for the first 5 days of the menstrual period. An 800 m TT was completed 1-3 days post-supplementation. All participants completed the protocol again with the counterbalanced substance at the start of the next menstrual period. RESULTS: A 2x2 mixed ANOVA revealed no significant interaction between training and condition, F(1,8) = 4.206, p = .074. The main effects of training and condition were significant; however, two paired t-tests found no significant differences between SP and P in both the TF and UTF groups (results as mean ± SD, TF = SP: 232.33 ± 55.10s, P: 250.00 ± 54.56 s, t = -3.649, p = .068; UTF = SP: 303.00 ± 32.50s, P:306.29 ± 28.99 s, t = -0.813, p = .447). A Pearson’s correlation test found a strong negative relationship between the amount of SP consumed and post SP TT performance (r = -.614). CONCLUSION: There were no significant differences between SP and P trials between TF and UTF. However, a negative correlation exists between amount of SP consumed and post SP TT performance. Our findings suggest a higher dose of SP may be needed in females to exhibit a significant, ergogenic effect. SIGNIFICANCE: Female SP research is limited. The current study sought to add to this relatively small pool to further women’s health and sports performance research. The authors declare no conflicts of interest.