EFFECT OF 30 DAYS OF CREATINE PHOSPHATE SUPPLEMENTATION ON THE CRITICAL POWER TEST IN MEN

Abstract

PURPOSE The purpose of the present study was to determine the effect of 30 d of single dose creatine phosphate (CrP) supplementation on critical power (CP) and anaerobic work capacity (AWC) in men. METHODS Twenty-eight men, who exercised at least 4 d·wk−1 for 60 min, volunteered for this study. Each subject first performed a critical power test (CPT) on an electronically braked cycle ergometer to familiarize themselves with the testing protocols, and to allow the investigators to estimate workloads for subsequent trials. The subjects were randomly assigned to one of two supplement conditions using a double-blind design: (1) 20 g of flavored dextrose powder as a placebo (PL) (n = 12), or (2) 5.0 g of creatine citrate plus 2 g of monobasic sodium phosphate + 2 g monobasic potassium phosphate and 18 g of dextrose (CrP) (n = 16). The powders were packaged to be identical in taste and appearance, and dissolved in 16 oz. of water for consumption. Prior to supplementation, subjects performed a second CPT to provide baseline (BL) values for CP and AWC. During the study, the subjects were asked to maintain their normal dietary and activity patterns. Upon completion of the 30 d supplementation protocol, the subjects completed a final CPT (30d) from which CP and AWC were calculated. The estimates of CP and AWC were calculated using a linear regression model (total work versus time to exhaustion). The CP and AWC data were analyzed using two repeated measures ANOV As (2×2, α < 0.05). RESULTS The results indicated that there was a significant (p < 0.05) increase in CP from BL to 30d for all subjects combined, however, there were no other significant comparisons in either ANOVA. CONCLUSIONS These findings suggest that supplementation with a single dose of CrP for 30 d did not have a significant effect on CP or AWC estimates in this group of males when compared to PL. Although there was a significant increase in CP for all subjects, this increase may have been due to an increased familiarization with the high intensity testing protocol. Supported by Nutricia, USA