Effect of Beetroot Juice on the physical performance of amateur swimmers

INTERVENTION: The present study is characterized as a randomized, double‐blind, crossover, placebo‐controlled clinical trial, with an expected total sample of 64 participants, composed of amateur swimmers of both sexes, aged between 18 and 59 years. Randomization will be performed using a computer‐generated random sequence to define the order of the experimental conditions through Randomizer. The allocation of the experimental conditions will be performed using balanced block randomization (1:1), with blocks composed of four participants each, with each block consisting of two men and two women. Double blinding will be adopted so that neither the participants nor the researchers responsible for data collection will be aware of the intervention administered in each session. All participants will receive both experimental conditions, characterizing a crossover design, with a minimum washout period of seven days between interventions. The intervention will consist of the acute administration of 70 mL of concentrated nitrate‐rich beetroot juice (approximately 6.4 mmol of nitrate), using the commercial product Beet It Sport (James White Drinks Ltd., United Kingdom), ingested approximately 2 hours and 30 minutes before the physical test, while the placebo will consist of a nitrate‐free beverage prepared with water, apple and lemon juice, red food coloring, and artificial berry flavoring, with sensory characteristics similar to beetroot juice. Following supplementation, participants will perform a simulated 1500‐meter swimming trial to assess physical performance. Total trial time, split times every 100 meters, rating of perceived exertion, and possible gastrointestinal symptoms will be analyzed. Anthropometric assessments and body composition analysis by bioelectrical impedance will also be performed. Participants will be instructed to record their dietary intake and physical activity routine during the 24 hours preceding the first test and to reproduce them before the second experimental session. All tests will be conducted during the same period of the day, between 08:00 a.m. and 12:00 p.m., in order to minimize circadian interference. CONDITION: G11.427.410.568.800 Physical Exertion; Heartburn ; Swimming PRIMARY OUTCOME: A reduction in the time required for the swimmer to complete the 1500 m time trial is expected. SECONDARY OUTCOME: It is expected that the intervention will influence the perception of effort during the 1500 m swimming trial. INCLUSION CRITERIA: Both sexes; aged between 18 and 59 years; healthy; with no reported chronic diseases; amateur swimming athletes, corresponding to levels 2 or 3