The effect of pre-exercise ingestion of corinthian currant on endurance performance and blood redox status

ABSTRACT

The present study investigated the effect of Corinthian currant pre-exercise supplementation on metabolism, performance and blood redox status during, and after prolonged exercise. Eleven healthy participants (21-45y) performed a 90-min constant-intensity (60–70% VO_2max) submaximal-trial, plus a time-trial (TT) to exhaustion (95% VO_2max) after consuming an isocaloric (1.5g CHO/kg BM) amount of randomly assigned Corinthian currant or glucose-drink, or water (control). Blood was drawn at baseline, pre-exercise, 30min, 60min, 90min of submaximal-trial, post-TT, and 1h post-TT. Post-ingestion blood glucose (GLU) under Corinthian currant was higher compared with water, and similar compared with glucose-drink throughout the study. Respiratory quotient under Corinthian currant was similar with glucose-drink and higher than water throughout the submaximal trial. Accordingly, higher CHO and lower fat oxidation were observed under Corinthian currant compared with water. The TT performance was similar between Corinthian currant, glucose-drink and water. Redox status were similar under all three conditions. Reduced glutathione (GSH) declined while total antioxidant capacity (TAC) and uric acid increased during exercise. GSH and TAC returned to baseline, while uric acid remained increased the following 1h. Corinthian currant, although did not alter exercise-mediated redox status changes and performance, was equally effective to a glucose-drink in maintaining GLU levels during prolonged cycling.

KEYWORDS:

• Raisins supplementation
• glucose homeostasis
• oxidative stress
• prolonged cycling

Acknowledgments

We would like to thank all the participants for their dedication to the study.

The study was designed by CKD, IGF, and AZJ; data were collected and analyzed by CKD, APo, KG, KP, APa, SM and DD; data interpretation was performed by CKD, IGF, YK, AT, VTK, and AZJ; preparation of the first version of the manuscript was undertaken by CKD, IGF, and AZJ. All authors reviewed and approved the final version of the paper.

Disclosure statement

No potential conflict of interest was reported by the authors.