Effect of sodium bicarbonate ingestion on athletic performance : an updated meta-analysis

Includes bibliographical references.A meta-analysis was conducted involving within-group, double-blind studies to determine the effect of sodium bicarbonate (NaHCOj) ingestion on athletic performance. The purpose of the study was to replicate an analysis published in 1993 by L. G. Matson and Z. V. Tran, who used a controversial approach in calculating and analyzing effect sizes. Fifty-three studies were collected, of which 30 met the criteria for inclusion. Thirty-six effect sizes were calculated either using information provided in the study or assuming a correlation between the experimental and placebo trials of .60 and .96. These values were used to compute effect sizes when insufficient information was reported by researchers. This resulted in the estimation of a lower (r=.60) and upper (r=.96) bounds of effect size. Weighted effect sizes for both the lower and upper bound were determined for all studies and levels of variables which might explain the variability in effect sizes. Large effect sizes calculated for r=.96 were found to be distorted by their variance in determining the weighted, overall effect size and were not considered to be credible. The overall treatment effect for the lower limit was 0.25. This translates into a .33-second improvement in 400-m time under alkalosis. Effect sizes were found to be homogeneous overall (QT, £>.05), and no differences were found among average effect sizes for levels of specific variables (e.g., dose, test duration, etc.) (Qb, £>.00625). There appears to be an ergogenic effect of 0.25 standard deviations; however, more studies employing a better methodology need to be conducted before the magnitude of the ergogenic effect can be described adequately.M.S. Ed. (Master of Education