Beetroot Beverage and Repeated Sprint Power Output During RAST

Overview

This randomized, double-blind, placebo-controlled crossover trial aims to evaluate the acute effects of a nitrate-rich beetroot-based beverage on repeated sprint performance in trained athletes. Ten athletes will complete two experimental conditions in randomized order: beetroot beverage (BET) and placebo (PLA), separated by a 7-day washout period. The beetroot beverage consists of 200 mL of a mixture containing beetroot, cocoa, and green tea, providing approximately 6.4 mmol of nitrate. In each condition, participants will perform a Running Anaerobic Sprint Test (RAST), consisting of six maximal 35-meter sprints with 10 seconds of passive recovery between sprints. The primary outcome is mean power output across the six sprints. Secondary outcomes include fatigue index, sprint-by-sprint power output, heart rate, rating of perceived exertion (Borg 6-20 scale), maximal oxygen uptake (VO₂max), and sleep quality assessed using the Insomnia Severity Index (ISI).

This randomized, double-blind, placebo-controlled crossover trial is designed to investigate the acute effects of a nitrate-rich beetroot-based beverage on repeated sprint performance in trained athletes. Ten athletes will participate in two experimental sessions in randomized order: beetroot beverage (BET) and placebo (PLA). Randomization will determine the sequence of beverage administration. Participants and investigators will be blinded to treatment allocation. After beverage ingestion, participants will perform a standardized warm-up followed by the Running Anaerobic Sprint Test (RAST), consisting of six maximal 35-meter sprints with 10 seconds of passive recovery between sprints. Sprint time will be recorded using electronic timing, and power output will be calculated using body mass and sprint time. The primary outcome measure is mean power output across all six sprints. Secondary outcomes include: Fatigue index (percentage decrement across sprints) Individual sprint power (S1-S6) Heart rate response Rating of perceived exertion (Borg 6-20 scale) VO₂max (assessed at baseline) Sleep quality measured using the Insomnia Severity Index (ISI) A linear mixed-effects model will be used to analyze repeated sprint performance, including subject as a random intercept and treatment, sprint, and their interaction as fixed effects. Non-parametric tests will be applied when assumptions of normality are not met. Statistical significance will be set at p ≤ 0.05.