Juçara (Euterpe edulis Martius) improves time-to-exhaustion cycling performance and increased reduced glutathione: a randomized, placebo-controlled, crossover, and triple-blind study

Abstract

To examine the effects of 7-days juçara powder (JP) intake on oxidative stress biomarkers and endurance and sprint cycling performances. In a randomized, placebo-controlled, crossover, and triple-blind study, 20 male trained cyclists were assigned to intake 10 g of JP (240 mg anthocyanins) or placebo (PLA) for 7 days and performed a cycling time-to-exhaustion (TTE). A 5 s cycling sprint was performed before and after the cycling TTE. Blood oxidative stress biomarkers and lactate concentration where evaluated 1 h before (T-1), immediately after (T0), and 1 h after (T1) the cycling TTE. The mean duration time for the cycling TTE was 8.4 ± 6.0% (63 ± 17 s) longer in the JP condition (JP: 751 ± 283 s) compared to PLA (688 ± 266 s) ( P < 0.019). Two-way repeated measures Analysis of variance showed an increase in the JP condition for reduced glutathione (GSH) ( P = 0.049) at T0 ( P = 0.039) and T1 ( P = 0.029) compared to PLA with a moderate effect size at T0 ( d = 0.61) and T1 ( d = 0.57). Blood lactate levels increased over time in both conditions ( P ≤ 0.001). No differences were observed for the post-TTE sprint fatigue index, total phenols, protein carbonyls, and glutathione peroxidase activity. Seven-day intake of JP improved cycling endurance performance and increased GSH levels but had no effect on lactate and cycling sprint-induced fatigue.